organic food cause and effect essay

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The effects of organic food on human health: a systematic review and meta-analysis of population-based studies

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Bibo Jiang, Jinzhu Pang, Junan Li, Lijuan Mi, Dongmei Ru, Jingxi Feng, Xiaoxu Li, Ai Zhao, Li Cai, The effects of organic food on human health: a systematic review and meta-analysis of population-based studies, Nutrition Reviews , 2023;, nuad124, https://doi.org/10.1093/nutrit/nuad124

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Although the nutritional composition of organic food has been thoroughly researched, there is a dearth of published data relating to its impact on human health.

This systematic review aimed to examine the association between organic food intake and health effects, including changes in in vivo biomarkers, disease prevalence, and functional changes.

PubMed, EMBASE, Web of Science, the Cochrane Library, and ClinicalTrials.gov were searched from inception through Nov 13, 2022.

Both observational and interventional studies conducted in human populations were included, and association between level of organic food intake and each outcome was quantified as “no association,” “inconsistent,” “beneficial correlation/harmful correlation,” or “insufficient”. For outcomes with sufficient data reported by at least 3 studies, meta-analyses were conducted, using random-effects models to calculate standardized mean differences.

Based on the included 23 observational and 27 interventional studies, the association between levels of organic food intake and (i) pesticide exposure biomarker was assessed as “beneficial correlation,” (ii) toxic metals and carotenoids in the plasma was assessed as “no association,” (iii) fatty acids in human milk was assessed as “insufficient,” (iv) phenolics was assessed as “beneficial”, and serum parameters and antioxidant status was assessed as “inconsistent”. For diseases and functional changes, there was an overall “beneficial” association with organic food intake, and there were similar findings for obesity and body mass index. However, evidence for association of organic food intake with other single diseases was assessed as “insufficient” due to the limited number and extent of studies.

Organic food intake was found to have a beneficial impact in terms of reducing pesticide exposure, and the general effect on disease and functional changes (body mass index, male sperm quality) was appreciable. More long-term studies are required, especially for single diseases.

PROSPERO registration no. CRD42022350175.

• biological markers
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Organic foods: Are they safer? More nutritious?

Discover the difference between organic foods and their traditionally grown counterparts when it comes to nutrition, safety and price.

Once found only in health food stores, organic food is now a common feature at most grocery stores. And that's made a bit of a problem in the produce aisle.

For example, you can pick an apple grown with usual (conventional) methods. Or you can pick one that's organic. Both apples are firm, shiny and red. They both provide vitamins and fiber. And neither apple has fat, salt or cholesterol. Which should you choose? Get the facts before you shop.

What is organic farming?

The word "organic" means the way farmers grow and process farming (agricultural) products. These products include fruits, vegetables, grains, dairy products such as milk and cheese, and meat. Organic farming practices are designed to meet the following goals:

• Improve soil and water quality
• Cut pollution
• Provide safe, healthy places for farm animals (livestock) to live
• Enable natural farm animals' behavior
• Promote a self-sustaining cycle of resources on a farm

Materials or methods not allowed in organic farming include:

• Artificial (synthetic) fertilizers to add nutrients to the soil
• Sewage sludge as fertilizer
• Most synthetic pesticides for pest control
• Using radiation (irradiation) to preserve food or to get rid of disease or pests
• Using genetic technology to change the genetic makeup (genetic engineering) of crops, which can improve disease or pest resistance, or to improve crop harvests
• Antibiotics or growth hormones for farm animals (livestock)

Organic crop farming materials or practices may include:

• Plant waste left on fields (green manure), farm animals' manure or compost to improve soil quality
• Plant rotation to keep soil quality and to stop cycles of pests or disease
• Cover crops that prevent wearing away of soil (erosion) when sections of land aren't in use and to plow into soil for improving soil quality
• Mulch to control weeds
• Insects or insect traps to control pests
• Certain natural pesticides and a few synthetic pesticides approved for organic farming, used rarely and only as a last choice and coordinated with a USDA organic certifying agent

Organic farming practices for farm animals (livestock) include:

• Healthy living conditions and access to the outdoors
• Pasture feeding for at least 30% of farm animals' nutritional needs during grazing season
• Organic food for animals
• Shots to protect against disease (vaccinations)

Organic or not? Check the label

The U.S. Department of Agriculture (USDA) has set up an organic certification program that requires all organic food to meet strict government standards. These standards control how such food is grown, handled and processed.

Any product labeled as organic on the product description or packaging must be USDA certified. If it's certified, the producer may also use an official USDA Organic seal.

The USDA says producers who sell less than $5,000 a year in organic food don't need to be certified. These producers must follow the guidelines for organic food production. But they don't need to go through the certification process. They can label their products as organic. But they can't use the official USDA Organic seal.

Products certified 95 percent or more organic may display this USDA seal.

The USDA guidelines describe organic foods on product labels as:

• 100% organic. This label is used on certified organic fruits, vegetables, eggs, meat or other foods that have one ingredient. It may also be used on food items with many ingredients if all the items are certified organic, except for salt and water. These may have a USDA seal.
• Organic. If a food with many ingredients is labeled organic, at least 95% of the ingredients are certified organic, except for salt and water. The items that aren't organic must be from a USDA list of approved additional ingredients. These also may have a USDA seal.
• Made with organic. If a product with many ingredients has at least 70% certified organic ingredients, it may have a "made with organic" ingredients label. For example, a breakfast cereal might be labeled "made with organic oats." The ingredient list must show what items are organic. These products can't carry a USDA seal.
• Organic ingredients. If a product has some organic ingredients but less than 70% of the ingredients are certified organic , the product can't be labeled as organic. It also can't carry a USDA seal. The ingredient list can show which ingredients are organic.

Does 'organic' mean the same thing as 'natural'?

No, "natural" and "organic" are different. Usually, "natural" on a food label means that the product has no artificial colors, flavors or preservatives. "Natural" on a label doesn't have to do with the methods or materials used to grow the food ingredients.

Also be careful not to mix up other common food labels with organic labels. For example, certified organic beef guidelines include pasture access during at least 120 days of grazing season and no growth hormones. But the labels "free-range" or "hormone-free" don't mean a farmer followed all guidelines for organic certification.

Organic food: Is it safer or more nutritious?

Some data shows possible health benefits of organic foods when compared with foods grown using the usual (conventional) process. These studies have shown differences in the food. But there is limited information to prove how these differences can give potential overall health benefits.

Potential benefits include the following:

• Nutrients. Studies have shown small to moderate increases in some nutrients in organic produce. Organic produce may have more of certain antioxidants and types of flavonoids, which have antioxidant properties.
• Omega-3 fatty acids. The feeding requirements for organic farm animals (livestock) usually cause higher levels of omega-3 fatty acids. These include feeding cattle grass and alfalfa. Omega-3 fatty acids — a kind of fat — are more heart healthy than other fats. These higher omega-3 fatty acids are found in organic meats, dairy and eggs.
• Toxic metal. Cadmium is a toxic chemical naturally found in soils and absorbed by plants. Studies have shown much lower cadmium levels in organic grains, but not fruits and vegetables, when compared with crops grown using usual (conventional) methods. The lower cadmium levels in organic grains may be related to the ban on synthetic fertilizers in organic farming.
• Pesticide residue. Compared with produce grown using usual (conventional) methods, organically grown produce has lower levels of pesticide residue. The safety rules for the highest levels of residue allowed on conventional produce have changed. In many cases, the levels have been lowered. Organic produce may have residue because of pesticides approved for organic farming or because of airborne pesticides from conventional farms.
• Bacteria. Meats produced using usual (conventional) methods may have higher amounts of dangerous types of bacteria that may not be able to be treated with antibiotics. The overall risk of contamination of organic foods with bacteria is the same as conventional foods.

Are there downsides to buying organic?

One common concern with organic food is cost. Organic foods often cost more than similar foods grown using usual (conventional) methods. Higher prices are due, in part, to more costly ways of farming.

Food safety tips

Whether you go totally organic or choose to mix conventional and organic foods, keep these tips in mind:

• Choose a variety of foods from a mix of sources. You'll get a better variety of nutrients and lower your chance of exposure to a single pesticide.
• Buy fruits and vegetables in season when you can. To get the freshest produce, ask your grocer what is in season. Or buy food from your local farmers market.
• Read food labels carefully. Just because a product says it's organic or has organic ingredients doesn't mean it's a healthier choice. Some organic products may still be high in sugar, salt, fat or calories.
• Wash and scrub fresh fruits and vegetables well under running water. Washing helps remove dirt, germs and chemical traces from fruit and vegetable surfaces. But you can't remove all pesticide traces by washing. Throwing away the outer leaves of leafy vegetables can lessen contaminants. Peeling fruits and vegetables can remove contaminants but may also cut nutrients.

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• Organic production and handling standards. U.S. Department of Agriculture. https://www.ams.usda.gov/publications/content/organic-production-handling-standards. Accessed March 30, 2022.
• Introduction to organic practices. U.S. Department of Agriculture. https://www.ams.usda.gov/publications/content/introduction-organic-practices. Accessed March 30, 2022.
• Organic labeling at farmers markets. U.S. Department of Agriculture. https://www.ams.usda.gov/publications/content/organic-labeling-farmers-markets. Accessed March 30, 2022.
• Labeling organic products. U.S. Department of Agriculture. https://www.ams.usda.gov/publications/content/labeling-organic-products. Accessed March 30, 2022.
• Use of the term natural on food labeling. U.S. Food and Drug Administration. https://www.fda.gov/food/food-labeling-nutrition/use-term-natural-food-labeling. Accessed March 30, 2022.
• Demory-Luce D, et al. Organic foods and children. https://www.uptodate.com/contents/search. Accessed March 30, 2022.
• Pesticides and food: Healthy, sensible food practices. U.S. Environmental Protection Agency. https://www.epa.gov/safepestcontrol/pesticides-and-food-healthy-sensible-food-practices. Accessed March 30, 2022.
• Vegetable and pulses outlook: November 2021. U.S. Department of Agriculture. https://www.ers.usda.gov/publications/pub-details/?pubid=102664. Accessed March 30, 2022.
• Changes to the nutrition facts label. U.S. Food and Drug Administration. https://www.fda.gov/food/food-labeling-nutrition/changes-nutrition-facts-label. Accessed March 30, 2022.
• Rahman SME, et al. Consumer preference, quality and safety of organic and conventional fresh fruits, vegetables, and cereals. Foods. 2021; doi:10.3390/foods10010105.
• Brantsaeter AL, et al. Organic food in the diet: Exposure and health implications. Annual Review of Public Health. 2017; doi:10.1146/annurev-publhealth-031816-044437.
• Vigar V, et al. A systematic review of organic versus conventional food consumption: Is there a measurable benefit on human health? Nutrients. 2019; doi:10.3390/nu12010007.
• Mie A, et al. Human health implications of organic food and organic agriculture: A comprehensive review. Environmental Health. 2017; doi:10.1186/s12940-017-0315-4.
• Innes GK, et al. Contamination of retail meat samples with multidrug-resistant organisms in relation to organic and conventional production and processing: A cross-sectional analysis of data from the United States National Antimicrobial Resistance Monitoring System, 2012-2017. Environmental Health Perspectives. 2021; doi:10.1289/EHP7327.

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Health benefits of organic food, farming outlined in new report

February 8, 2017 – A report prepared for the European Parliament, co-authored by Harvard Chan School’s Philippe Grandjean , adjunct professor of environmental health, outlines the health benefits of eating organic food and practicing organic agriculture.

Why did the European Parliament commission this report and what was its most important takeaway?

The European Parliament is concerned about food safety and human health. They asked a group of experts from several countries to review the possible health advantages of organic food and organic farming. Our report reviews existing scientific evidence regarding the impact of organic food on human health, including in vitro and animal studies, epidemiological studies, and food crop analyses.

The most important information in this report is about pesticides in food. In conventional food, there are pesticide residues that remain in the food even after it’s washed. Organic foods are produced virtually without pesticides.

Authorities in both the European Union and the United States insist that current limits on the amount of pesticides in conventional produce are adequate to ensure that it’s perfectly safe. But those limits are based on animal studies, looking at the effect of one pesticide at a time. The human brain is so much more complex than the rat brain, and our brain development is much more vulnerable because there are so many processes that have to happen at the right time and in the right sequence—you can’t go back and do them over.

Three long-term birth cohort studies in the U.S. suggest that pesticides are harming children’s brains. In these studies, researchers found that women’s exposure to pesticides during pregnancy, measured through urine samples, was associated with negative impacts on their children’s IQ and neurobehavioral development, as well as with ADHD [attention deficit hyperactivity disorder] diagnoses. Also, one of the studies looked at structural brain growth using magnetic resonance imaging and found that the gray matter was thinner in children the higher their mothers’ exposure to organophosphates, which are used widely in pesticides. I think that’s quite scary.

Although the scientific evidence on pesticides’ impact on the developing brain is incomplete, pregnant and breastfeeding women, and women planning to become pregnant, may wish to eat organic foods as a precautionary measure because of the significant and possibly irreversible consequences for children’s health. If there are times when organic food isn’t available, one option is to buy foods that have to be peeled—baking potatoes or pineapples, for example—but stay away from produce like leafy vegetables. A good resource for learning about the pesticide content of various foods is the  Environmental Working Group , which maintains lists of produce with the highest pesticide levels as well as those with the lowest levels. There’s also a U.S. Environmental Protection Agency website that lists ways to reduce exposure to pesticides in food.

What were other key messages in the report?

We know that the overly prevalent use of antibiotics in farm animals is a contributing factor in the development of antibiotic resistance in bacteria—a major public health threat because this resistance can spread from animals to humans. On organic farms, the preventive use of antibiotics is restricted and animals are given more space to roam in natural conditions, which lowers their risk for infections. These techniques have been found to improve animal health, prevent disease, and minimize antibiotic resistance.

There are also other, though minor, advantages of organic food, such as higher contents of some nutrients, and less cadmium, but they are not of sufficient importance to guide food choices.

How might the European Parliament boost support for organic foods and organic farming? If it does, might that prompt similar changes in the U.S.?

Our report listed several policy options the European Parliament could consider to support and extend organic food production. For instance, politicians could decrease or waive taxes on organic food. They could decrease taxation on organic farmers. We also suggest that they support more research to learn more about the benefits of organic food.

If the European Parliament does take action, I hope it could influence practices also in the U.S. There is a lot of exchange of foods between the European Union and the U.S. Clearly, if the EU is going to favor organic products more in the future, that will open up an opportunity for U.S. producers of organic foods. And vice versa: If more products become available from EU farmers that are organic, that could be attractive to U.S. consumers. And perhaps the joint effect of that could be that organic farming, both in Europe and in the U.S., would become more sustainable economically as well as environmentally.

— Karen Feldscher

Organic food: panacea for health? ( The Lancet )

Read a slightly abbreviated version of the organic food report to the EU Parliament published October 27, 2017 in the journal Biomed Central : “Human health implications of organic food and organic agriculture: a comprehensive review”

*Editor’s note: This story was updated on February 12, 2017.

• Open access
• Published: 27 October 2017

Human health implications of organic food and organic agriculture: a comprehensive review

• Axel Mie   ORCID: orcid.org/0000-0001-8053-3541 1 , 2 ,
• Helle Raun Andersen 3 ,
• Stefan Gunnarsson 4 ,
• Johannes Kahl 5 ,
• Emmanuelle Kesse-Guyot 6 ,
• Ewa Rembiałkowska 7 ,
• Gianluca Quaglio 8 &
• Philippe Grandjean 3 , 9  

Environmental Health volume  16 , Article number:  111 ( 2017 ) Cite this article

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This review summarises existing evidence on the impact of organic food on human health. It compares organic vs. conventional food production with respect to parameters important to human health and discusses the potential impact of organic management practices with an emphasis on EU conditions. Organic food consumption may reduce the risk of allergic disease and of overweight and obesity, but the evidence is not conclusive due to likely residual confounding, as consumers of organic food tend to have healthier lifestyles overall. However, animal experiments suggest that identically composed feed from organic or conventional production impacts in different ways on growth and development. In organic agriculture, the use of pesticides is restricted, while residues in conventional fruits and vegetables constitute the main source of human pesticide exposures. Epidemiological studies have reported adverse effects of certain pesticides on children’s cognitive development at current levels of exposure, but these data have so far not been applied in formal risk assessments of individual pesticides. Differences in the composition between organic and conventional crops are limited, such as a modestly higher content of phenolic compounds in organic fruit and vegetables, and likely also a lower content of cadmium in organic cereal crops. Organic dairy products, and perhaps also meats, have a higher content of omega-3 fatty acids compared to conventional products. However, these differences are likely of marginal nutritional significance. Of greater concern is the prevalent use of antibiotics in conventional animal production as a key driver of antibiotic resistance in society; antibiotic use is less intensive in organic production. Overall, this review emphasises several documented and likely human health benefits associated with organic food production, and application of such production methods is likely to be beneficial within conventional agriculture, e.g., in integrated pest management.

Peer Review reports

The long-term goal of developing sustainable food systems is considered a high priority by several intergovernmental organisations [ 1 , 2 , 3 ]. Different agricultural management systems may have an impact on the sustainability of food systems, as they may affect human health as well as animal wellbeing, food security and environmental sustainability. In this paper, we review the available evidence on links between farming system (conventional vs organic) and human health.

Food production methods are not always easy to classify. This complexity stems from not only the number and varying forms of conventional and organic agricultural systems but also resulting from the overlap of these systems. In this paper, we use the term “conventional agriculture” as the predominant type of intensive agriculture in the European Union (EU), typically with high inputs of synthetic pesticides and mineral fertilisers, and a high proportion of conventionally-produced concentrate feed in animal production. Conversely, “organic agriculture” is in accordance with EU regulations or similar standards for organic production, comprising the use of organic fertilisers such as farmyard and green manure, a predominant reliance on ecosystem services and non-chemical measures for pest prevention and control and livestock access to open air and roughage feed.

In 2015, over 50.9 million hectares, in 179 countries around the world, were cultivated organically, including areas in conversion [ 4 ]. The area under organic management (fully converted and in-conversion) has increased during the last decades in the European Union, where binding standards for organic production have been developed [ 5 , 6 ]. In the 28 countries forming the EU today, the fraction of organically cultivated land of total agricultural area has been steadily increasing over the last three decades. 0.1%, 0.6%, 3.6%, and 6.2% of agricultural land were organic in 1985, 1995, 2005, and 2015, respectively, equalling 11.2 million ha in 2015 [ 7 , 8 , 9 ]. In 7 EU Member States, at least 10% of the agricultural land is organic [ 7 ]. In 2003, 125,000 farms in the EU were active in organic agriculture, a number that increased to 185,000 in 2013 [ 10 ]. Between 2006 and 2015, the organic retail market has grown by 107% in the EU, to €27.1 billion [ 7 ].

This review details the science on the effects of organic food and organic food production on human health and includes

studies that directly address such effects in epidemiological studies and clinical trials.

animal and in vitro studies that evaluate biological effects of organic compared to conventional feed and food.

Focusing on narrower aspects of production, we then discuss the impact of the production system on

plant protection, pesticide exposure, and effects of pesticides on human health,

plant nutrition, the composition of crops and the relevance for human health,

animal feeding regimens, effects on the composition of animal foods and the relevance for human health.

animal health and well-being, the use of antibiotics in animal production, its role in the development of antibiotic resistance, and consequences of antibiotic resistance for public health.

In the discussion, we widen the perspective from production system to food system and sustainable diets and address the interplay of agricultural production system and individual food choices. The consequences of these aspects on public health are briefly discussed.

Due to a limited evidence base, minimal importance, lack of a plausible link between production system and health, or due to lack of relevance in the European Union, we do not or only briefly touch upon

singular food safety events such as outbreaks of diseases that are not clearly caused by the production system (hygiene regulations for plant production and for animal slaughtering and processing are for the most part identical for organic and conventional agriculture) or fraudulent introduction of contaminated feed into the feed market

historic events and historic sources of exposure, such as the BSE crisis caused by the now-banned practice of feeding cattle with meat and bone meal from cattle, or continuing effects of the historic use of DDT, now banned in all agricultural contexts globally

contaminants from food packaging

aspects of food processing, such as food additives

the presence of mycotoxins in consequence of post-harvest storage and processing which is governed chiefly by moisture and temperature in storage

the use of growth hormones in animal production, which is not permitted in the EU but in several other countries

Furthermore, aspects of environmental sustainability, such as biodiversity and greenhouse gas emissions, may also be affected by the agricultural production system [ 11 , 12 ] and may affect human health via food security [ 13 , 14 ]. While these indirect links are outside the scope of this review, we briefly touch on them in the discussion. Also, the focus of this article is on public health, not on occupational health of agricultural workers or local residents, although these issues are considered as part of the epidemiological evidence on pesticide effects. While agricultural standards vary between countries and regions, we maintain a global perspective when appropriate and otherwise focus on the European perspective.

The literature search for this review was carried out at first using the PubMed and Web of Science databases, while applying “organic food” or “organic agriculture” along with the most relevant keywords, through to the end of 2016 (more recent references were included, when relevant, although they were not identified through the systematic search). We made use of existing systematic reviews and meta-analyses when possible. In some cases, where scientific literature is scarce, we included grey literature e.g. from authorities and intergovernmental organisations. We also considered references cited in the sources located.

Association between organic food consumption and health: Findings from human studies

A growing literature is aiming at characterizing individual lifestyles, motivations and dietary patterns in regard to organic food consumption, which is generally defined from responses obtained from food frequency questionnaires [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. Still, current research on the role of organic food consumption in human health is scarce, as compared to other nutritional epidemiology topics. In particular, long-term interventional studies aiming to identify potential links between organic food consumption and health are lacking, mainly due to high costs. Prospective cohort studies constitute a feasible way of examining such relationships, although compliance assessment is challenging. Considering a lack of biomarkers of exposure, the evaluation of the exposure, i.e. organic food consumption, will necessarily be based on self-reported data that may be prone to measurement error.

Some recent reviews have compiled the findings [ 24 , 25 , 26 ] from clinical studies addressing the association between consumption of organic food and health. These studies are scant and generally based on very small populations and short durations, thus limiting statistical power and the possibility to identify long-term effects. Smith-Spangler et al. [ 25 ] summarised the evidence from clinical studies that overall no clinically significant differences in biomarkers related to health or to nutritional status between participants consuming organic food compared to controls consuming conventional food. Among studies of nutrient intakes, the OrgTrace cross-over intervention study of 33 males, the plant-based fraction of the diets was produced in controlled field trials, but 12 days of intervention did not reveal any effect of the production system on the overall intake or bioavailability of zinc and copper, or plasma status of carotenoids [ 27 , 28 ].

In observational studies, a specific challenge is the fact that consumers who regularly buy organic food tend to choose more vegetables, fruit, wholegrain products and less meat, and tend to have overall healthier dietary patterns [ 18 , 29 ]. Each of these dietary characteristics is associated with a decreased risk for mortality from or incidence of certain chronic diseases [ 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. Consumers who regularly buy organic food are also more physically active and less likely to smoke [ 18 , 19 , 37 ]. Depending on the outcome of interest, associations between organic vs conventional food consumption and health outcome therefore need to be carefully adjusted for differences in dietary quality and lifestyle factors, and the likely presence of residual confounding needs to be considered. In children, several studies have reported a lower prevalence of allergy and/or atopic disease in families with a lifestyle comprising the preference of organic food [ 38 , 39 , 40 , 41 , 42 , 43 , 44 ]. However, organic food consumption is part of a broader lifestyle in most of these studies and associated with other lifestyle factors. Thus, in the Koala birth cohort of 2700 mothers and babies from the Netherlands [ 39 ], exclusive consumption of organic dairy products during pregnancy and during infancy was associated with a 36% reduction in the risk of eczema at age 2 years. In this cohort, the preference of organic food was associated with a higher content of ruminant fatty acids in breast milk [ 40 ], which in turn was associated with a lower odds ratio for parent-reported eczema until age 2y [ 45 ].

In the MOBA birth cohort study of 28,000 mothers and their offspring, women reporting a frequent consumption of organic vegetables during pregnancy exhibited a reduction in risk of pre-eclampsia [ 29 ] (OR = 0.79, 95% CI 0.62 to 0.99). No significant association was observed for overall organic food consumption, or five other food groups, and pre-eclampsia.

The first prospective study investigating weight change over time according to the level of organic food consumption included 62,000 participants of the NutriNet-Santé study. BMI increase over time was lower among high consumers of organic food compared to low consumers (mean difference as % of baseline BMI = − 0.16, 95% Confidence Interval (CI): −0.32; −0.01). A 31% (95% CI: 18%; 42%) reduction in risk of obesity was observed among high consumers of organic food compared to low consumers. Two separate strategies were chosen to properly adjust for confounders [ 46 ]. This paper thus confirms earlier cross-sectional analyses from the same study [ 18 ].

In regard to chronic diseases, the number of studies is limited. In the Nutrinet-Santé study, organic food consumers (occasional and regular), as compared to non-consumers, exhibited a lower incidence of hypertension, type 2 diabetes, hypercholesterolemia (in both males and females), and cardiovascular disease (in men) [ 47 ] but more frequently declared a history of cancer. Inherent to cross-sectional studies, reverse causation cannot be excluded; for example, a cancer diagnosis by itself may lead to positive dietary changes [ 48 ].

Only one prospective cohort study conducted in adults addressed the effect of organic food consumption on cancer incidence. Among 623,080 middle-aged UK women, the association between organic food consumption and the risk of cancer was estimated during a follow-up period of 9.3 y. Participants reported their organic food consumption through a frequency question as never, sometimes, or usually/always. The overall risk of cancer was not associated with organic food consumption, but a significant reduction in risk of non-Hodgkin lymphoma was observed in participants who usually/always consume organic food compared to people who never consume organic food (RR = 0.79, 95% CI: 0.65; 0.96) [ 37 ].

In conclusion, the link between organic food consumption and health remains insufficiently documented in epidemiological studies. Thus, well-designed studies characterized by prospective design, long-term duration and sufficient sample size permitting high statistical power are needed. These must include detailed and accurate data especially for exposure assessment concerning dietary consumption and sources (i.e. conventional or organic).

Experimental in vitro and animal studies

In vitro studies.

The focus on single plant components in the comparison of crops from organic and conventional production, as discussed further below, disregards the fact that compounds in food do not exist and act separately, but in their natural context [ 49 ]. In vitro studies of effects of entire foods in biological systems such as cell lines can therefore potentially point at effects that cannot be predicted from chemical analyses of foods, although a limitation is that most cells in humans are not in direct contact with food or food extracts.

Two studies have investigated the effect of organic and conventional crop cultivation on cancer cell lines, both using crops produced under well-documented agricultural practices and with several agricultural and biological replicates. In the first study extracts from organically grown strawberries exhibited stronger antiproliferative activity against one colon and one breast cancer cell line, compared to the conventionally produced strawberries [ 50 ]. In the second study [ 51 ] the extracts of organic naturally fermented beetroot juices induced lower levels of early apoptosis and higher levels of late apoptosis and necrosis in a gastric cancer cell line, compared to the conventional extracts. Both studies thus demonstrated notable differences in the biological activity of organic vs. conventionally produced crop extracts in vitro, which should inspire further research. However, neither of these studies allows for the distinction of a selective antiproliferative effect on cancer cells, and general cell toxicity. Therefore it cannot be determined which of the organic or conventional food extracts, if any, had the preferable biological activity in terms of human health.

Animal studies of health effects

Considering the difficulties of performing long-term dietary intervention studies in humans, animal studies offer some potential of studying long-term health effects of foods in vivo. However, extrapolation of the results from animal studies to humans is not straight-forward. Studies in this field started almost 100 years ago. A review of a large number of studies [ 52 ] concluded that positive effects of organic feed on animal health are possible, but further research is necessary to confirm these findings. Here we focus on the main health aspects.

In one of the best-designed animal studies, the second generation chickens receiving the conventionally grown feed demonstrated a faster growth rate. However, after an immune challenge, chickens receiving organic feed recovered more quickly [ 53 ]. This resistance to the challenge has been interpreted as a sign of better health [ 54 , 55 ].

In one carefully conducted crop production experiment, followed by a rat feeding trial, the production system had an apparent effect on plasma-IgG concentrations but not on other markers of nutritional or immune status [ 56 ]. A two-generational rat study based on feed grown in a factorial design (fertilisation x plant protection) of organic and conventional practices revealed that the production system had an effect on several physiological, endocrine and immune parameters in the offspring [ 57 ]. Most of the effects identified were related to the fertilisation regimen. None of these studies found that any of the feed production systems was more supportive of animal health.

Several other studies, mostly in rats, have reported some effect of the feed production system on immune system parameters [ 57 , 58 , 59 , 60 ]. However, the direct relevance of these findings for human health is uncertain.

Collectively, in vitro and animal studies have demonstrated that the crop production system does have an impact on certain aspects of cell life, the immune system, and overall growth and development. However, the direct relevance of these findings for human health is unclear. On the other hand, these studies may provide plausibility to potential effects of conventional and organic foods on human health. Still, most of the outcomes observed in animal studies have not been examined in humans so far.

Plant protection in organic and conventional agriculture

Plant protection in conventional agriculture is largely dependent on the use of synthetic pesticides. Conversely, organic farming generally relies on prevention and biological means for plant protection, such as crop rotation, intercropping, resistant varieties, biological control employing natural enemies, hygiene practices and other measures [ 61 , 62 , 63 , 64 ]. Yet, certain pesticides are approved for use in organic agriculture. In the EU, pesticides (in this context, more specifically chemical plant-protection products; micro- and macrobiological agents are excluded from this discussion due to their low relevance for human health) are approved after an extensive evaluation, including a range of toxicological tests in animal studies [ 65 ]. Acceptable residue concentrations in food are calculated from the same documentation and from the expected concentrations in accordance with approved uses of the pesticides. Currently, 385 substances are authorised as pesticides in the EU (Table  1 ). Of these , 26 are also approved for use in organic agriculture [ 6 , 66 ] as evaluated in accordance with the same legal framework.

Most of the pesticides approved for organic agriculture are of comparatively low toxicological concern for consumers because they are not associated with any identified toxicity (e.g. spearmint oil, quartz sand), because they are part of a normal diet or constitute human nutrients (e.g. iron, potassium bicarbonate, rapeseed oil) or because they are approved for use in insect traps only and therefore have a negligible risk of entering the food chain (i.e. the synthetic pyrethroids lambda-cyhalothrin and deltamethrin, and pheromones). Two notable exceptions are the pyrethrins and copper. Pyrethrins, a plant extract from Chrysanthemum cinerariaefolium, share the same mechanism of action as the synthetic pyrethroid insecticides, but are less stable. Copper is an essential nutrient for plants, animals and humans, although toxic at high intakes and of ecotoxicological concern due to toxicity to aquatic organisms.

Plant protection practices developed in and for organic agriculture may be of benefit to the entire agricultural system [ 67 , 68 , 69 , 70 ]. This is of specific value for the transition towards sustainable use of pesticides in the EU, which has a strong emphasis on non-chemical plant protection measures including prevention and biological agents [ 63 , 64 ]. Further, steam treatment of cereal seeds for the prevention of fungal diseases ( http://thermoseed.se/ ) has been developed driven by the needs of organic agriculture as an alternative to chemical seed treatments [ 71 , 72 ]. These methods are now also being marketed for conventional agriculture, specifically for integrated pest management (IPM) [ 73 ].

Pesticide use – Exposure of consumers and producers

One main advantage of organic food production is the restricted use of synthetic pesticides [ 5 , 6 ], which leads to low residue levels in foods and thus lower pesticide exposure for consumers. It also reduces the occupational exposure of farm workers to pesticides and drift exposures of rural populations. On average over the last three available years, EFSA reports pesticide residues below Maximum Residue Levels (MRL) in 43.7% of all and 13.8% of organic food samples. MRLs reflect the approved use of a pesticide rather than the toxicological relevance of the residue. There are no separate MRLs for organic products. A total of 2.8% of all and 0.9% of organic samples exceeded the MRL, which may be due to high residue levels or due to low levels but unapproved use of a particular pesticide on a particular crop [ 74 , 75 , 76 ]. Of higher toxicological relevance are risk assessments, i.e. expected exposure in relation to toxicological reference values. On average 1.5% of the samples were calculated to exceed the acute reference dose (ARfD) for any of the considered dietary scenarios, with the organophosphate chlorpyrifos accounting for approximately half of these cases and azole fungicides (imazalil, prochloraz, and thiabendazole) for approximately 15%. None (0%) of the organic samples exceeded the ARfD [ 74 ]. Residues of more than one pesticide were found in approximately 25% of the samples but calculations of cumulative risks were not included in the reports [ 74 , 75 , 76 ].

The only cumulative chronic risk assessment comparing organic and conventional products known to us has been performed in Sweden. Using the hazard index (HI) method [ 77 ], adults consuming 500 g of fruit, vegetables and berries per day in average proportions had a calculated HI of 0.15, 0.021 and 0.0003, under the assumption of imported conventional, domestic conventional, and organic products, respectively [ 78 ]. This indicates an at least 70 times lower exposure weighted by toxicity for a diet based on organic foods. There are several routes by which pesticides not approved for use in organic agriculture may contaminate organic products, including spray drift or volatilisation from neighbouring fields, fraudulent use, contamination during transport and storage in vessels or storages where previously conventional products have been contained, and mislabelling by intention or mistake. Overall, however, current systems for the certification and control of organic products ensure a low level of pesticide contamination as indicated by chronic and acute risks above, although they still can be improved [ 79 ].

The general population’s exposure to several pesticides can be measured by analysing blood and urine samples, as is routinely done in the US [ 80 ] although not yet in Europe. However, a few scattered European studies from France [ 81 , 82 , 83 ], Germany [ 84 ], the Netherlands [ 85 ], Spain [ 86 ], Belgium [ 87 ], Poland [ 88 ] and Denmark [ 89 ] have shown that EU citizens are commonly exposed to organophosphate and pyrethroid insecticides. A general observation has been higher urinary concentrations of pesticide metabolites in children compared to adults, most likely reflecting children’s higher food intake in relation to body weight and maybe also more exposure-prone behaviours. The urinary concentrations of generic metabolites of organophosphates (dialkyl phosphates, DAPs) and pyrethroids (3-phenoxybenzoic acid, 3-PBA) found in most of the European studies were similar to or higher than in the US studies. Although urinary metabolite concentration might overestimate the exposure to the parent compounds, due to ingestion of preformed metabolites in food items, several studies have reported associations between urinary metabolite concentrations and neurobehavioral deficits as described below. Besides, the metabolites are not always less toxic than the parent compounds [ 90 ].

For the general population, pesticide residues in food constitute the main source of exposure for the general population. This has been illustrated in intervention studies where the urinary excretion of pesticides was markedly reduced after 1 week of limiting consumption to organic food [ 91 , 92 , 93 ]. Similar conclusions emerged from studies investigating associations between urinary concentrations of pesticides and questionnaire information on food intake, frequency of different foodstuffs and organic food choices. Thus a high intake of fruit and vegetables is positively correlated with pesticide excretion [ 94 ], and frequent consumption of organic produce is associated with lower urinary pesticide concentration [ 95 ].

Pesticide exposure and health effects

The regulatory risk assessment of pesticides currently practised in the EU is comprehensive, as a large number of toxicological effects are addressed in animal and other experimental studies. Nonetheless, there are concerns that this risk assessment is inadequate at addressing mixed exposures, specifically for carcinogenic effects [ 96 ] as well as endocrine-disrupting effects [ 97 , 98 ] and neurotoxicity [ 99 ]. Furthermore, there are concerns that test protocols lag behind independent science [ 100 ], studies from independent science are not fully considered [ 101 ] and data gaps are accepted too readily [ 102 ]. These concerns primarily relate to effects of chronic exposure and to chronic effects of acute exposure, which are generally more difficult to discover than acute effects. Most studies rely on urinary excretion of pesticide metabolites and a common assumption is that the subjects were exposed to the parent chemicals, rather than the metabolites.

The overall health benefits of high fruit and vegetable consumption are well documented [ 31 , 35 ]. However, as recently indicated for effects on semen quality [ 103 ], these benefits might be compromised by the adverse effects of pesticide residues. When benefits are offset by a contaminant, a situation of inverse confounding occurs, which may be very difficult to adjust for [ 104 ]. The potential negative effects of dietary pesticide residues on consumer health should of course not be used as an argument for reducing fruit and vegetable consumption. Neither should nutrient contents be used to justify exposures to pesticides. Exposures related to the production of conventional crops (i.e. occupational or drift exposure from spraying) have been related to an increased risk of some diseases including Parkinson’s disease [ 105 , 106 , 107 ], type 2 diabetes [ 108 , 109 ] and certain types of cancers including non-Hodgkin lymphoma [ 110 ] and childhood leukaemia or lymphomas, e.g. after occupational exposure during pregnancy [ 105 , 111 ] or residential use of pesticides during pregnancy [ 105 , 112 ] or childhood [ 113 ]. To which extent these findings also relate to exposures from pesticide residues in food is unclear. However, foetal life and early childhood are especially vulnerable periods for exposure to neurotoxicants and endocrine disruptors. Even brief occupational exposure during the first weeks of pregnancy, before women know they are pregnant, have been related to adverse long-lasting effects on their children’s growth, brain functions and sexual development, in a Danish study on greenhouse worker’s children [ 114 , 115 , 116 , 117 , 118 ].

In order to assess the potential health risk for consumers associated with exposure to dietary pesticides, reliance on epidemiological studies of sensitive health outcomes and their links to exposure measures is needed. Such studies are complicated both by difficult exposure assessment and the necessary long-term follow-up. The main focus so far has been on cognitive deficits in children in relation to their mother’s exposure level to organophosphate insecticides during pregnancy. This line of research is highly appropriate given the known neurotoxicity of many pesticides in laboratory animal models [ 99 ] and the substantial vulnerability of the human brain during early development [ 119 ].

Most of the human studies have been carried out in the US and have focused on assessing brain functions in children in relation to prenatal organophosphate exposure. In a longitudinal birth cohort study among farmworkers in California (the CHAMACOS cohort), maternal urinary concentrations of organophosphate metabolites in pregnancy were associated with abnormal reflexes in neonates [ 120 ], adverse mental development at 2 years of age [ 121 ], attention problems at three and a half and 5 years [ 122 ], and poorer intellectual development at 7 years [ 123 ]. In accordance with this, a birth cohort study from New York reported impaired cognitive development at ages 12 and 24 months and 6 – 9 years related to maternal urine concentrations of organophosphates in pregnancy [ 124 ]. In another New York inner-city birth cohort, the concentration of the organophosphate chlorpyrifos in umbilical cord blood was associated with delayed psychomotor and mental development in children in the first 7 years of life [ 125 ], poorer working memory and full-scale IQ at 7 years of age [ 126 ], structural changes, including decreased cortical thickness, in the brain of the children at school age [ 127 ], and mild to moderate tremor in the arms at 11 years of age [ 128 ]. Based on these and similar studies, chlorpyrifos has recently been categorised as a human developmental neurotoxicant [ 129 ]. Recent reviews of neurodevelopmental effects of organophosphate insecticides in humans conclude that exposure during pregnancy – at levels commonly found in the general population – likely have negative effects on children’s neurodevelopment [ 130 , 131 , 132 ]. In agreement with this conclusion, organophosphate pesticides considered to cause endocrine disruption contribute the largest annual health cost within the EU due to human exposures to such compounds, and these costs are primarily due to neurodevelopmental toxicity, as discussed below.

Since growth and functional development of the human brain continues during childhood, the postnatal period is also assumed to be vulnerable to neurotoxic exposures [ 119 ]. Accordingly, five-year-old children from the CHAMACOS cohort had higher risk scores for development of attention deficit hyperactive disorder (ADHD) if their urine concentration of organophosphate metabolites was elevated [ 122 ]. Based on cross-sectional data from the NHANES data base, the risk of developing ADHD increases by 55% for a ten-fold increase in the urinary concentration of organophosphate metabolites in children aged 8 to 15 years [ 133 ]. Also based on the NHANES data, children with detectable concentrations of pyrethroids in their urine are twice as likely to have ADHD compared with those below the detection limit [ 134 ]. In addition, associations between urinary concentrations of pyrethroid metabolites in children and parent-reported learning disabilities, ADHD or other behavioural problems in the children have recently been reported in studies from the US and Canada [ 135 , 136 ].

So far only few prospective studies from the EU addressing associations between urinary levels of pesticides and neurodevelopment in children from the general population have been published. Three studies are based on the PELAGIE cohort in France and present results for organophosphates and pyrethroids respectively [ 81 , 82 , 137 ]. While no adverse effects on cognitive function in six-year-old children were related to maternal urine concentrations of organophosphates during pregnancy, the concentration of pyrethroid metabolites was associated with internalising difficulties in the children at 6 years of age. Also, the children’s own urinary concentrations of pyrethroid metabolites were related to decrements in verbal and memory functions and externalising difficulties and abnormal social behaviour. While this sole European study did not corroborate US birth cohort studies results showing that exposure during pregnancy to organophosphate insecticides at levels found in the general population may harm brain development in the foetus, the exposure levels measured in the PELAGIE cohort were considerably lower for both organophosphates and pyrethroids than those measured in other European studies as well as in studies from the US and Canada. For example, the median urine concentration of organophosphate metabolites in pregnant women in the PELAGIE cohort was 2 – 6 times lower than for pregnant women in other studies [ 85 , 122 , 138 ] and the concentration of the common pyrethroid metabolite 3-PBA was only detectable in urine samples from 30% of the women compared to 80–90% in other studies [ 88 , 139 ]. Thus, to supplement the French study and the previously mentioned Danish study of greenhouse worker’s children, additional studies that include more representative exposure levels for EU citizens are desirable.

Although exposure levels found in European countries are generally similar to or slightly higher than concentrations found in the US studies, the risk of adverse effects on neurodevelopment in European populations needs to be further characterised. The organophosphate insecticides contributing to the exposure might differ between the US and the EU, also in regard to oral and respiratory intakes. According to the European Food Safety Agency (EFSA), of all the organophosphate insecticides, chlorpyrifos most often exceeds the toxicological reference value (ARfD) [ 74 ]. A recent report utilised US data on adverse effects on children’s IQ levels at school age to calculate the approximate costs of organophosphate exposure in the EU. The total number of IQ points lost due to these pesticides was estimated to be 13 million per year, representing a value of about € 125 billion [ 140 ], i.e. about 1% of the EU’s gross domestic product. Although there is some uncertainty associated with this calculation, it most likely represents an underestimation, as it focused only on one group of pesticides.

Unfortunately, epidemiological evidence linking pesticide exposure and human health effects is rarely regarded as sufficiently reliable to take into account in the risk assessment conducted by regulatory agencies. For example, the conclusion from the epidemiological studies on chlorpyrifos is that an association of prenatal chlorpyrifos exposure and adverse neurodevelopmental outcomes is likely, but that other neurotoxic agents cannot be ruled out, and that animal studies show adverse effects only at 1000-fold higher exposures [ 141 ]. A recent decrease of the maximum residue limit for chlorpyrifos in several crops [ 142 , 143 ] was based on animal studies only [ 144 ], but the limits for the sister compound, chlorpyrifos-methyl were unchanged. This case highlights a major limitation to current approaches to protecting the general population against a broad variety of pesticides.

Production system and composition of plant foods

Fertilisation in organic agriculture is based on organic fertilisers such as farmyard manure, compost and green fertilisers, while some inorganic mineral fertilisers are used as supplements. Nitrogen (N) input is limited to 170 kg/ha * year [ 5 , 145 ]. In conventional agriculture, fertilisation is dominated by mineral fertiliser, although farmyard manure is also common in some countries. There is no general limit on N input. Typically, crop yield is limited by plant N availability in organic but not in conventional systems [ 146 ] Phosphorus (P) input is on average similar or slightly lower in organic systems [ 147 ].

In the absence of particular nutrient deficiency, focusing on single nutrients may be of limited value for evaluating the impact of a food or diet on human health [ 49 ]; studies of actual health effects, as discussed above, are generally more informative than studies of single nutrients.

Overall crop composition

Metabolomics [ 148 , 149 , 150 , 151 , 152 ], proteomics [ 153 , 154 ] and transcriptomics [ 155 , 156 ] studies in controlled field trials provide evidence that the production system has an overall influence on crop development, although there is no direct relevance of these studies for human health. Furthermore, the generally lower crop yield in organic systems [ 146 ] as such indicates an effect of management strategy on plant development.

Several systematic reviews and meta-analyses [ 25 , 157 , 158 , 159 ] with different scopes, inclusion criteria and statistical methods have summarised several hundred original studies reporting some aspect of plant chemical composition in relation to conventional and organic production, in search of overall trends across crops, varieties, soils, climates, production years etc. While the overall conclusions of these systematic reviews look contradictory at first sight, there is agreement between them in most of the detailed findings:

Nitrogen and phosphorus

Existing systematic reviews have consistently found lower total nitrogen (7% [ 157 ], 10% [ 159 ]) and higher phosphorus (standardised mean difference (SMD) 0.82 [ 25 ], 8% [ 157 ]) in organic compared to conventional crops. These findings lack direct relevance for human health. However, considering the differences in fertilisation strategies discussed above, and the fundamental importance of N, P [ 160 , 161 , 162 ], and the N:P ratio [ 163 ] for plant development, this may lend some plausibility to other observed effects of the production system on crop composition.

Systematic reviews generally agree that the concentration of macronutrients, vitamins, and minerals in crops is either not at all or only slightly affected by the production system. For example, ascorbic acid (vitamin C) has received most attention in this context. Meta-analyses report only small effect sizes of the organic production system on vitamin C content [ 25 , 158 , 159 ].

Polyphenols

(Poly)phenolic compounds are not essential nutrients for humans but may play a role in preventing several non-communicable diseases, including cardiovascular disease, neurodegeneration and cancer [ 164 ]. The detailed mechanisms are complex and not fully understood [ 164 ]. Several environmental and agronomic practices affect the phenolic composition of the crop, including light, temperature, availability of plant nutrients and water management [ 165 ]. Under conditions of high nitrogen availability, many plant tissues show a decreased content of phenolic compounds, although there are examples of an opposite relationship [ 165 ].

Meta-analyses report modest effect sizes of the production system on total phenolics content, e.g. an increase of 14 – 26% [ 25 , 158 , 159 ]. For some narrower groups of phenolic compounds, larger relative concentration differences (in percent) between organic and conventional crops have been reported [ 159 ]. However, such findings represent unweighted averages typically from small and few studies, and are therefore less reliable.

Collectively the published meta-analyses indicate a modestly higher content of phenolic compounds in organic food, but the evidence available does not constitute a sufficient basis for drawing conclusions on positive effects of organic compared to conventional plant products in regard to human health.

Cadmium and other toxic metals

Cadmium (Cd) is toxic to the kidneys, can demineralise bones and is carcinogenic [ 166 ]. Cd is present naturally in soils, and is also added to soils by P fertilisers and atmospheric deposition. Several factors, including soil structure and soil chemistry, humus content and pH, affect the plant availability of Cd [ 167 ]. The application of Cd-containing fertilisers increases Cd concentrations in the crops [ 167 , 168 ]. Low soil organic matter generally increases the availability of Cd for crops [ 169 ], and organically managed farms tend to have higher soil organic matter than conventionally managed farms [ 11 ].

The source of Cd in mineral fertilisers is the raw material phosphate rock. The European average Cd content in mineral fertilisers is reported as 68 mg Cd/kg P [ 170 ] or 83 mg Cd/kg P [ 171 ]. The content of Cd in farmyard manure is variable but apparently in many cases lower: Various types of animal manure in a German collection averaged between 14 and 37 mg Cd/kg P [ 172 ].

Smith-Spangler et al. [ 25 ] found no significant difference in the Cd content of organic and conventional crops (SMD = −0.14, 95% CI -0.74 – 0.46) in their meta-analysis, while Barański et al. [ 159 ] report significantly 48% higher Cd concentration in conventional compared to organic crops (SMD = -1.45, 95% CI -2.52 to −0.39) in another meta-analysis largely based on the same underlying original studies, albeit with different inclusion criteria. We contacted the authors of these meta-analyses in order to understand this discrepancy. An updated version of the Barański meta-analysis, in which some inconsistencies have been addressed and which has been provided by the original authors [ 173 ], shows a significant 30% (SMD = −0.56, 95% CI -1.08 to −0.04) elevations of Cd contents in conventional compared to organic crops; in subgroup analysis, this difference is restricted to cereal crops. No updated meta-analysis was available for Smith-Spangler’s analysis [ 25 ]; apparently, two large well-designed studies with tendencies towards a lower Cd content in organic crops were not considered [ 174 , 175 ] although they appear to fulfil the inclusion criteria. Also, a correction for multiple testing has been imposed, which may be overly conservative, given the prior knowledge that mineral fertilisers constitute an important source of Cd to soils and crops. It is unclear how these points would affect the results of Smith-Spangler’s meta-analysis.

There are short-term and long-term effects of Cd influx from fertilisers on the Cd content of crops [ 167 ] but no long-term study comparing Cd content in organic and conventional crops is available. In absence of such direct evidence, two long-term experiments indicate a higher slope in Cd concentration over time for minerally fertilised compared to organically fertilised cereal crops [ 176 , 177 ], after over 100 years of growing.

A lower Cd content of organic crops is therefore plausible due to a lower Cd content in the fertilisers used in organic farming, and potentially due to higher soil organic matter in organic farmland. The general population’s Cd exposure is close to, and in some cases above, the tolerable intake and therefore their exposure to Cd should be reduced. For non-smokers, food is the primary source of exposure, with cereals and vegetables being the most important contributors [ 168 ].

For other toxic metals including lead, mercury and arsenic, no differences in concentration in organic and conventional crops have been reported [ 25 , 159 ]. Uranium (U) is also present as a contaminant of concern in mineral P fertilisers [ 178 ], but less so in organic fertilisers [ 179 ], and consequently manure-based cropping systems have a lower U load than mineral-fertilised systems at equal P load [ 179 ]. Uranium appears to accumulate in mineral-fertilised soils [ 180 ], and agricultural activity may increase the U content of surface and groundwater [ 181 , 182 ]. However, no evidence was found comparing uranium contents of organic and conventional products.

Fungal toxins

Regarding fungal toxins in crops, one meta-analysis has reported a lower contamination of organic compared to conventional cereal crops with deoxynivalenol (DON), produced by certain fusarium species [ 25 ]. Although not fully understood, fungicide applications may alter fungal communities on cereal leaves, potentially weakening disease-suppressive species [ 183 , 184 ]. Also, crop rotations including non-cereal crops may contribute to lower infestation with fusarium [ 185 ], while N availability is positively associated with cereal DON content [ 186 ]. These factors give plausibility to the observed lower DON contamination in organic cereals. In the EU, the mean chronic exposure of toddlers, infants and children to DON is above the tolerable daily intake (TDI), with grains and grain-based products being the main contributors to total exposure. The TDI is based on decreased body weight gain observed in mice [ 187 ]. The production system does not have any observed effect on the concentration of ochratoxin A (OTA), another fungal toxin of importance in cereal production [ 25 ].

Animal-based foods

By regulation, herbivores in organic production receive at least 60% of their feed intake as roughage on a dry matter basis. Depending on the seasonal availability of pastures, roughage can be fresh, dried, or silage. Also omnivores in organic production receive roughage as part of their daily feed, and poultry has access to pasture [ 6 ]. Corresponding regulations are for the most part missing in conventional animal production. In consequence, feeding strategies in organic animal production include a higher fraction of roughage compared to conventional systems, e.g. for dairy cows [ 188 , 189 ].

Fatty acids

Much of the focus of existing research on compositional differences of organic and conventional animal-based foods is on the fatty acid composition, with a major interest in omega-3 FAs due to their importance for human health. Some studies also address the content of minerals and vitamins.

The FA composition of the feed is a strong determinant of the fatty acid composition of the milk, egg or meat [ 190 , 191 ]. Grass and red clover, typical roughage feeds, contain between 30% and 50% omega-3 FA of total FA, while the concentrate feeds cereals, soy, corn, and palm kernel cake all contain below 10% omega-3 FA of total FA [ 190 ]. Like humans, farm animals turn a small part of dietary alpha-linolenic acid into long-chain omega-3 fatty acids with the help of elongase and desaturase enzymes.

For cow’s milk, a recent meta-analysis reports conclusively an approximately 50% higher content of total omega-3 fatty acids (as percent of total fatty acids) in organic compared to conventional milk [ 192 ], generally confirming earlier reviews [ 25 , 189 ]. Also, the content of ruminant FAs (a group of natural trans FAs produced in the cow’s rumen) is higher in organic milk. The content of saturated fatty acids, mono-unsaturated fatty acids and omega-6 PUFA was similar in organic and conventional milk [ 192 ].

A considerable statistical heterogeneity in these findings is reported. Individual differences described above are based on results from between 11 and 19 included studies. The observed differences are plausible, because they are directly linked to differences in feeding regimens. It should also be noted that several other factors influence the fatty acid composition in milk [ 193 ]. Specifically, the season (indoor vs. outdoor) has an impact on the feeding regime [ 188 ] and therefore on the omega-3 content of milk. However, the content of omega-3 fatty acids is higher in organic milk during both the outdoor and indoor seasons [ 189 ].

For eggs, it is likewise well described that the FA composition of the feed [ 190 ] and consequently the access to pasture [ 194 , 195 ] such as in organic systems, is a strong determinant of the fatty acid composition of the egg. However, only few studies have compared the FA composition in organic and conventional eggs [ 196 ] and a systematic review is not available. A higher omega-3 content of organic eggs is plausible but has not been documented.

A total of 67 original studies report compositional aspects of meat (mainly beef, chicken, lamb, and pork) from organic and conventional husbandry and were recently summarised in a meta-analysis [ 197 ]. Based on 23 and 21 studies respectively, the content of total PUFA and omega-3 PUFA was found to be significantly higher (23 and 47%, respectively) in organic compared to conventional meats. Weighted by average consumption in Europe, choosing organic instead of conventional meat, while maintaining a constant consumption, increased the intake of PUFA and omega-3 FA from meat by 17 and 22%, respectively [ 198 ]. These findings are plausible, especially in the case of omega-3 PUFA, considering the known differences in feeding regimens in organic and conventional production. However, few studies were available for each analysis, leaving many analyses with high uncertainty and poor statistical power. Furthermore, fatty acid metabolism differs between ruminants and monogastric animals [ 190 ]. Also, the actual differences in feeding regimens between conventionally and organically raised animals may differ by species, and by country. The variation between studies and between species was large, and the overall reliability of these results is therefore lower compared to milk above. This meta-analysis therefore indicates a plausible increase in omega-3 contents in organic meats, but more well-designed studies are needed to confirm this effect [ 197 ].

Dairy products account for 4–5% of the total PUFA intake in most European populations, while meat and meat products contribute another 7–23% [ 199 ]. The contribution of milk fat to omega-3 PUFA intake (approximated as intake of α-linolenic acid) has been estimated at 5–16% [ 200 , 201 ], while meat contributes with 12–17% [ 201 , 202 ]. The effect of exchanging organic for conventional dairy products on omega-3 PUFA intake while maintaining a constant consumption has not been examined rigorously. From the intake and composition data presented here, it can be estimated that choosing organic products would increase the average dietary omega-3 PUFA intake by 2.5–8% (dairy) and by a less certain 2.5–4% (meat). A recent preliminary estimate based on FAO food supply data resulted in similar numbers [ 198 ]. For certain population groups and fatty acids, these numbers could be higher, and an increased omega-3 PUFA consumption is generally desirable, as some subpopulations have a lower-than-recommended intake of omega-3 PUFA [ 203 ]. However, overall, the effect of the animal production system on omega-3 PUFA intake is minor, and no specific health benefits can be derived. Furthermore, other dietary omega-3 PUFA sources, specifically certain plant oils and fish, are available that carry additional benefits [ 204 , 205 , 206 ]. The existence of specific health benefits of ruminant trans fatty acids (as opposed to industrial trans fatty acids) is indicated by some studies [ 207 ] but not strongly supported [ 208 ]. Taking into account the actually consumed amounts of ruminant trans fatty acids, this is likely lacking public health relevance [ 208 ].

Trace elements and vitamins

A recent meta-analysis points to a significantly higher content of iodine (74%) and selenium (21%) in conventional milk and of iron (20%) and tocopherol (13%) in organic milk based on six, four, eight and nine studies respectively [ 192 ]. Iodine deficiency during pregnancy and infancy leads to impairment of brain development in the offspring, while excess iodine intake is associated with similar effects, and the window of optimal iodine intake is relatively narrow [ 209 ]. Overall, iodine intake in Europe is low and mild deficiency is prevalent [ 210 ]. The preferred way of correcting deficiency is salt iodisation [ 210 , 211 ], because salt is consumed almost universally and with little seasonal variation [ 212 ].

Feed iodine supplementation is not linked by regulation to the production system in the EU, as iodine is listed as approved feed additive, and the maximum amount of supplementation is the same for all milk production. Optimum dairy cow supplementation should be seen in relation to other national strategies for human iodine intake. This should also take into account human subpopulations with low or no intake of dairy products.

For tocopherol, selenium and iron, a higher content is generally desirable, and in the case of selenium milk is an important source. However, the concentration differences between organic and conventional milk are modest and based on a few studies only.

Antibiotic resistant bacteria

Overly prevalent prophylactic use of antibiotics in animal production is an important factor contributing to increasing human health problems due to resistant bacteria. Antibiotic use is strongly restricted in organic husbandry, which instead aims to provide good animal welfare and enough space in order to promote good animal health.

Antibiotics constitute an integral part of intensive animal production today, and farm animals may act as important reservoirs of resistant genes in bacteria [ 213 , 214 ]. It is reported that a substantial proportion (50 – 80%) of antibiotics are used for livestock production worldwide [ 215 ]. On a “per kg biomass” basis, in 2014, the amount of antimicrobial drugs consumed by farm animals was slightly higher than the antimicrobial drugs used for humans in the 28 EU/EEA countries surveyed, with substantial differences between countries regarding volumes and types of substances [ 216 ].

In recent decades, there have been increasing concerns that the use of antibiotics in livestock would contribute to impairing the efficiency of antibiotic treatment in human medical care [ 217 ]. Despite the lack of detailed information on transmission routes for the vast flora of antibiotic-resistant bacteria and resistance genes, there is a global need for action to reduce the emerging challenges associated with the reduced efficiency of antibiotics and its consequences for public health, as well as for the environment more generally [ 218 , 219 ].

The use of antibiotics may increase the economic outcome of animal production [ 220 , 221 ], but the spreading of multi-resistant genes is not just a problem for the animal production sector alone. Negative effects are affecting parts of society not directly associated with livestock production. This means that the costs of side effects are borne by society in general and not primarily by the agricultural sector. However, the generalisation cannot be made that all antibiotic treatment in farm animals represents a hazard to public health [ 222 , 223 ].

The use of antibiotics in intensive livestock production is closely linked to the housing and rearing conditions of farm animals. Specific conditions for conventional livestock farming in different countries, as well as farmers’ attitudes, may differ between countries, e.g. conventional pig production at above EU animal welfare standards and farmers’ attitudes in Sweden [ 224 , 225 ]. Conventional production is typically aiming for high production levels with restricted input resources such as space, feed etc., and these conditions may cause stress in the individual animal as it is unable to cope with the situation, e.g. in pig production [ 226 , 227 ]. This means that higher stocking density, restricted space and barren environment are factors increasing the risk of the development of diseases, and therefore it is more likely that animals under these conditions need antibiotic treatments.

Organic production aims for less intensive animal production, which generally means that the animals have access to a more spacious and enriched environment, access to an outdoor range and restricted group sizes, and other preconditions [ 70 ]. This would ultimately decrease the need for preventive medication of the animals as they can perform more natural behaviours and have more opportunity to maintain a good health. However, in practice, the health status of organic livestock is complex and disease prevention needs to be adapted to the individual farm [ 228 ]. A report on the consequences of organic production in Denmark demonstrates that meeting the requirements of organic production has several positive consequences in relation to animal welfare and health [ 70 ].

According to EU regulations, routine prophylactic medication of animals in organic production is not allowed. However, diseases should be treated immediately to avoid suffering, and the therapeutic use of antibiotics is allowed, but with longer withdrawal periods than in conventional production [ 5 ]. Furthermore, products from animals treated more than three times during 12 months, or, if their productive lifecycle is less than 1 year, more than once, cannot be sold as organic [ 6 ]. This means that therapeutically the same antibiotics used in conventional farming may be used in organic farming, but under different conditions. For example, antibiotics mainly used for sub-therapeutic treatment as prophylaxis are never considered in organic production.

While the organic regulations aim for a low use of antibiotics in livestock production, the actual use of antibiotic drugs in European organic compared to conventional animal husbandry is not comprehensively documented. Scattered studies indicate that the antibiotic use generally is substantially higher in conventional compared to organic systems, especially for pigs (approximately 5 – 15-fold higher) [ 229 , 230 ]. In studies from Denmark [ 231 ] and the Netherlands [ 232 ], the antibiotic use in dairy cows was 50% and 300% higher in conventional compared to organic systems, although a Swedish study found no differences in disease treatment strategies between organic and conventional dairy farms, e.g. for mastitis [ 233 ]. While only sparingly documented (e.g. [ 234 , 235 ]), there is only little use of antibiotics in EU organic broiler production. This is a consequence of regulations prohibiting prophylactic use and prescribing long withdrawal periods before slaughter [ 6 , 236 ], in conjunction with the fact that it is not feasible to treat single animals in broiler flocks. In conventional broiler production, antibiotic use is common (e.g. [ 237 , 238 , 239 ]).

Recently, gene sequencing has revealed that the routes of transmission of resistance genes between human and farm animal reservoirs seem to be complex [ 213 , 222 , 240 ]. Nevertheless, a recent EFSA report found that “in both humans and animals, positive associations between consumption of antimicrobials and the corresponding resistance in bacteria were observed for most of the combinations investigated” [ 241 ], which has subsequently been strengthened [ 216 ]. In addition to direct transmission between animals and humans via contact or via food, resistant strains and resistance genes may also spread into the environment [ 242 ].

Previously, it has been postulated that a reduced need and use of antibiotics in organic livestock production will diminish the risk of development of antibiotic resistance [ 243 ], and this has also been demonstrated with regard to resistant E. coli in organic pigs compared to conventional pigs [ 244 ]. It has also been shown that the withdrawal of prophylactic use of antibiotics when poultry farms are converted from conventional to organic production standards leads to a decrease in the prevalence of antibiotic-resistant Salmonella [ 245 ].

Resistant bacteria may be transferred within the production chain from farm to fork [ 246 ]. It has been found that organic livestock products are less likely to harbour resistant bacteria in pork and chicken meat [ 25 ].

In pig production, particular attention has been paid to methicillin-resistant Staphylococcus aureus (MRSA), and in Dutch and German studies, for example, MRSA has been isolated in 30 and 55% respectively of all pigs tested [ 247 , 248 ]. Furthermore, it has been found that healthy French pig farmers are more likely to carry MRSA than control persons [ 249 ] and that they carry similar strains of MRSA to those found on their pig farms [ 250 ]. However, the prevalence of MRSA in pig production may differ between conventional and organic farms, and in a meta-study in 400 German fattening pig herds, the odds ratio (OR) for MRSA prevalence was 0.15 (95% CI 0.04, 0.55) in organic ( n  = 23) compared to conventional ( n  = 373) pig farms [ 248 ]. Multivariate adjustment for potential risk factors rendered this association non-significant, suggesting that it was carried by other factors, including factors that are regulated in or associated with organic production, such as non-slatted floors, no use of antibiotics, and farrow-to-finish herd types. Furthermore, even if there are considerable differences in antibiotic use between countries, it has been found that antibiotic resistance is less common in organic pigs compared to conventional pigs in France, Italy, Denmark, and Sweden [ 251 , 252 ].

Although it is rare for conventional farms to adopt knowledge about management and housing from organic production except when converting farms in line with organic standards, there may be options to improve animal health and welfare by knowledge transfer to conventional farms in order to reduce the use of antibiotics [ 253 ].

Within organic production, labelling requires full traceability in all steps in order to guarantee the origin of the organic products being marketed [ 5 ]. Application of the general principle of organic regulations about transparency throughout the food chain can be used to mitigate emerging problems of transmission of antimicrobial resistance. However, transition to organic production for the whole livestock sector would, on its own, be only part of a solution to the antibiotics resistance issue, because factors outside animal production, such as their use in humans, will be unaffected.

An assessment of the human health effects associated with diets based on organic food production must rely on two sets of evidence. The first set of evidence is the epidemiological studies comparing population groups with dietary habits that differ substantially in regard to choices of organic v. conventional products. These studies are to some extent complemented by experimental studies using animal models and in vitro models. The second set of data relies on indirect evidence such as chemical analyses of food products and their contents of nutrients and contaminants or antibiotic use and resistance patterns, in onsequence of agricultural production methods. Both sets of results are associated with certain strengths and weaknesses.

The few human studies that have directly investigated the effects of organic food on human health have so far yielded some observations, including indications of a lower risk of childhood allergies, adult overweight/obesity [ 18 , 46 ] and non-Hodgkin lymphoma (but not for total cancer) [ 37 ] in consumers of organic food. Owing to the scarcity or lack of prospective studies and the lack of mechanistic evidence, it is presently not possible to determine whether organic food plays a causal role in these observations. However, it has also been observed that consumers who prefer organic food have healthier dietary patterns overall, including a higher consumption of fruit, vegetables, whole grains, and legumes and a lower consumption of meat [ 18 , 29 , 37 ]. This leads to some methodological difficulties in separating the potential effect of organic food preference from the potential effect of other associated lifestyle factors, due to residual confounding or unmeasured confounders. These dietary patterns have in other contexts been associated with a decreased risk of several chronic diseases, including diabetes and cardiovascular disease [ 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. It is therefore expected that consumers who regularly eat organic food have a decreased risk of these diseases compared to people consuming conventionally-produced food, as a consequence of dietary patterns. These dietary patterns appear also to be more environmentally sustainable than average diets [ 254 ].

Food analyses tend to support the notion that organic foods may have some health benefits. Consumers of organic food have a comparatively low dietary exposure to pesticides. Although chemical pesticides undergo a comprehensive risk assessment before market release in the EU, there are important gaps in this risk assessment. In some cases, specifically for cognitive development during childhood as an effect of organophosphate insecticide exposure during pregnancy, epidemiological studies provide evidence of adverse effects [ 140 , 255 ]. Organic agriculture allows for lower pesticide residues in food and may be instrumental in conventional agriculture’s transition towards integrated pest management by providing a large-scale laboratory for non-chemical plant protection.

This review emphasizes that pesticide exposure from conventional food production constitutes a main health concern. A key issue that has only recently been explored in biomedical research is that early-life exposure is of major concern, especially prenatal exposure that may harm brain development. Most insecticides are designed to be toxic to the insect nervous system, but many higher species depend on similar neurochemical processes and may therefore all be vulnerable to these substances [ 129 ]. Besides insecticides, experimental studies suggest a potential for adverse effects on the nervous system for many herbicides and fungicides as well [ 99 ]. However, no systematic testing is available since testing for neurotoxicity – especially developmental neurotoxicity – has not consistently been required as part of the registration process, and allowable exposures may therefore not protect against such effects. At least 100 different pesticides are known to cause adverse neurological effects in adults [ 129 ], and all of these substances must therefore be suspected of being capable of damaging also developing brains. The need for prevention of these adverse outcomes is illustrated by the recent cost calculations [ 140 ] and the additional risk that pesticide exposures may lead to important diseases, such as Parkinson’s disease, diabetes and certain types of cancer.

The outcomes in children and adults and the dose-dependences are still incompletely documented, but an additional limitation is the lack of exposure assessments in different populations and also their association with dietary habits. The costs from pesticide use in regard to human health and associated costs to society are likely to be greatly underestimated due to hidden and external costs, as recently reviewed [ 256 ]. Also, gaps in the regulatory approval process of pesticides may lead to important effects being disregarded and remaining undetected.

In regard to nutrients, organic dairy products, and probably also meat, have an approximately 50% higher content of omega-3 fatty acids compared to conventional products. However, as these products only are a minor source of omega-3 fatty acids in the average diet, the nutritional significance of this effect is probably low (although this has not been proven). The nutritional content of crops is largely unaffected by the production system, according to current knowledge. Vitamins and minerals are found in similar concentrations in crops from both systems. One exception is the increased content of phenolic compounds found in organic crops, although this is still subject to uncertainty despite a large number of studies that have addressed this issue. Accordingly, although in general being favourable for organic products, the established nutritional differences between organic and conventional foods are small, and strong conclusions for human health cannot currently be drawn from these differences. There are indications that organic crops contain less cadmium compared to conventional crops. This is plausible, primarily because mineral fertiliser is an important source of cadmium in soils. However, notably, long-term farm pairing studies or field trials that are required for definitely establishing or disproving this relationship are lacking. Owing to the high relevance of cadmium in food for human health, this lack of research constitutes an important knowledge gap.

With respect to the development of antibiotic resistance in bacteria, organic animal production may offer a way of restricting the risks posed by intensive production, and even decreasing the prevalence of antibiotic resistance. Organic farm animals are less likely to develop certain diseases related to intensive production compared to animals on conventional farms. As a consequence, less antibiotics for treating clinical diseases are required under organic management, where their prophylactic use also is strongly restricted. This decreases the risk for development of antibiotic resistance in bacteria. Furthermore, the transparency in organic production may be useful for acquiring knowledge and methods to combat the rising issues around transmission of antimicrobial resistance within food production.

It appears essential that use of antibiotics in animal production decreases strongly or completely ceases in order to decrease the risk of entering a post-antibiotic era. The development and upscaling of rearing systems free or low in antibiotic use, such as organic broiler production, may be an important contribution of organic agriculture to a future sustainable food system.

Most of the studies considered in this review have investigated the effects of agricultural production on product composition or health. Far less attention has been paid to the potential effects of food processing. Processing may affect the composition of foods and the bioavailability of food constituents. It is regulated [ 5 ] and recognised [ 257 ] that food additives are restricted for organic products compared to conventional products. It is also recognised that the degree of food processing may be of relevance to human health [ 258 , 259 ]. In organic food processing, the processing should be done “with care, preferably with the use of biological, mechanical and physical methods” [ 5 ] but there are no specific restrictions or guidelines. With the exception of chemical additives, it is unknown whether certain food processing methods (e.g. fermentation of vegetables, pasteurisation of vegetables) are more prevalent in organic or conventional products or consumption patterns, or whether such differences are of relevance to human health.

The scopes of two recent reports, from Norway [ 260 ] and Denmark [ 70 ], in part overlap with the present work. Broadly, the reviewed results and conclusions presented in those reports are in line with this article. For several topics, important new evidence has been published in recent years. Consequently, in some cases stronger conclusions can be drawn today. Furthermore, the present review includes epidemiological studies of pesticide effects in the evidence base reviewed.

Over all, the evidence available suggested some clear and some potential advantages associated with organic foods. The advantages in general do not necessarily require organic food production as strictly defined in current legislation. Certain production methods, such as changes in the use of pesticides and antibiotics, can be implemented in conventional production, e.g. supporting a development towards a sustainable use of pesticides [ 261 ]. Thereby, practices and developments in organic agriculture can have substantial public health benefits also outside the organic sector.

Diet choices and the associated food production methods also have important impacts on environmental sustainability [ 254 ]. Consumption patterns of consumers preferring organic food [ 16 , 18 , 19 , 37 , 47 ] seem to align well with sustainable diets [ 2 ]. These consumption patterns also show some similarities with the Mediterranean Diet [ 262 , 263 , 264 , 265 ] and with the New Nordic Diet [ 266 , 267 , 268 , 269 ], with lower dietary footprints in regard to land use, energy and water consumption, and greenhouse gas emissions compared to concurrent average diets. Further evaluation is needed to assess the extent to which organic food systems can serve as example of a sustainable food systems [ 270 ].

For the development of healthy and environmentally-sustainable food systems in the future, production and consumption need to be considered in an integrated manner [ 2 , 271 ]. While an evaluation of overall impacts of different food systems on environmental sustainability would be highly desirable [ 270 ], the present review has attempted to assess the human health issues in regard to organic production methods and consumer preferences for organic food, both important aspects of sustainability.

Conclusions

Suggestive evidence indicates that organic food consumption may reduce the risk of allergic disease and of overweight and obesity, but residual confounding is likely, as consumers of organic food tend to have healthier lifestyles overall. Animal experiments suggest that growth and development is affected by the feed type when comparing identically composed feed from organic or conventional production. In organic agriculture, the use of pesticides is restricted, and residues in conventional fruits and vegetables constitute the main source of human exposures. Epidemiological studies have reported adverse effects of certain pesticides on children’s cognitive development at current levels of exposure, but these data have so far not been applied in the formal risk assessments of individual pesticides. The nutrient composition differs only minimally between organic and conventional crops, with modestly higher contents of phenolic compounds in organic fruit and vegetables. There is likely also a lower cadmium content in organic cereal crops. Organic dairy products, and perhaps also meats, have a higher content of omega-3 fatty acids compared to conventional products, although this difference is of likely of marginal nutritional significance. Of greater concern is the prevalent use of antibiotics in conventional animal production as a key driver of antibiotic resistance in society; antibiotic use is less intensive in organic production. Thus, organic food production has several documented and potential benefits for human health, and wider application of these production methods also in conventional agriculture, e.g., in integrated pest management, would therefore most likely benefit human health.

Abbreviations

3-phenoxybenzoic acid

Attention deficit hyperactivity disorder

Acceptable daily intake

Acceptable operator exposure level

Acute reference dose

Body mass index

Bovine spongiform encephalopathy

Center for the health assessment of mothers and children of Salinas

Confidence interval

Dialkyl phosphate

Dichlorodiphenyltrichloroethane

Deoxynivalenol

Escherichia coli

European Economic Area

European Food Safety Authority

European Union

Food and Agriculture Organization of the United Nations

Hazard index

Immunoglobulin G

Integrated pest management

Intelligence quotient

Maximum residue level

Methicillin-resistant Staphylococcus aureus

National health and nutrition examination survey

Ochratoxin A

Persistent, bioaccumulative, toxic

Perturbateurs endocriniens: étude longitudinale sur les anomalies de la grossesse, l’infertilité et l’enfance (endocrine disruptors: longitudinal study on disorders of pregnancy, infertility and children)

Polyunsaturated fatty acid

Relative risk

Standardized mean difference

Tolerable daily intake

United Kingdom

United States

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Acknowledgements

The present review was initiated after a workshop entitled “The impact of organic food on human health” organized by the European Parliament in Brussels, Belgium on 18 November 2015, in which several of the authors participated, and which resulted in a formal report to the European Parliament [ 199 ]. The present review is an updated and abbreviated version aimed for the scientific community. The authors would like to thank the following colleagues for critically reading and reviewing sections of the review: Julia Baudry, Nils Fall, Birgitta Johansson, Håkan Jönsson, Denis Lairon, Kristian Holst Laursen, Jessica Perry, Paula Persson, Helga Willer and Maria Wivstad. The authors would also like to thank Marcin Barański and Gavin Stewart for providing additional meta-analyses of cadmium contents in organic and conventional crops. The STOA staff is acknowledged for organising the seminar in Brussels.

The Science and Technology Options Assessment Panel of the European Parliament provided funding for writing this paper, travel support to the authors and coverage of incidental expenses.

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University of Southern Denmark, Department of Public Health, Odense, Denmark

Helle Raun Andersen & Philippe Grandjean

Swedish University of Agricultural Sciences (SLU), Department of Animal Environment and Health, Skara, Sweden

Stefan Gunnarsson

University of Copenhagen, Department of Nutrition, Exercise and Sports, Frederiksberg, Denmark

Johannes Kahl

Research Unit on Nutritional Epidemiology (U1153 Inserm, U1125 INRA, CNAM, Université Paris 13), Centre of Research in Epidemiology and Statistics Sorbonne Paris Cité, Bobigny, France

Emmanuelle Kesse-Guyot

Warsaw University of Life Sciences, Department of Functional & Organic Food & Commodities, Warsaw, Poland

Ewa Rembiałkowska

Scientific Foresight Unit (Science and Technology Options Assessment [STOA]), Directorate-General for Parliamentary Research Services (EPRS), European Parliament, Brussels, Belgium

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Harvard T.H. Chan School of Public Health, Department of Environmental Health, Boston, USA

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AM, PG and GQ drafted the introduction. EKG drafted the human studies section. JK drafted the food consumption pattern aspects in the human studies section and in the discussion. AM and ER drafted the in vitro and animal studies section. HRA and PG drafted the pesticides section. AM and ER drafted the plant foods section. AM drafted the animal foods section. SG drafted the antibiotic resistance section. AM and PG drafted the discussion and conclusions. All authors commented on the entire draft and approved the final version.

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The authors have no conflict of interest to report. AM has participated as an expert witness in a court case in Sweden related to pesticide exposure from organic and conventional foods (Patent and Market Courts, case no. PMT11299–16), but did not benefit financially from this effort. PG is an editor of this journal but recused himself from participating in the handling of this manuscript.

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Mie, A., Andersen, H.R., Gunnarsson, S. et al. Human health implications of organic food and organic agriculture: a comprehensive review. Environ Health 16 , 111 (2017). https://doi.org/10.1186/s12940-017-0315-4

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A Systematic Review of Organic Versus Conventional Food Consumption: Is There a Measurable Benefit on Human Health?

Vanessa vigar.

1 NatMed Research, Southern Cross University, Lismore NSW 2480, Australia; [email protected] (V.V.); [email protected] (C.O.); [email protected] (S.R.)

2 Integria Healthcare, Eight Mile Plains QLD 4113, Australia

3 School of Health and Human Sciences, Southern Cross University, Lismore NSW 2480, Australia; [email protected]

4 Centre for Organics Research, Southern Cross University, Lismore NSW 2480, Australia

Stephen Myers

Christopher oliver.

5 Oliver Nutrition Pty Ltd, Lismore NSW 2480, Australia

Jacinta Arellano

Shelley robinson, carlo leifert, associated data.

The current review aims to systematically assess the evidence related to human health outcomes when an organic diet is consumed in comparison to its conventional counterpart. Relevant databases were searched for articles published to January 2019. Clinical trials and observational research studies were included where they provided comparative results on direct or indirect health outcomes. Thirty-five papers met the criteria for inclusion in the review. Few clinical trials assessed direct improvements in health outcomes associated with organic food consumption; most assessed either differences in pesticide exposure or other indirect measures. Significant positive outcomes were seen in longitudinal studies where increased organic intake was associated with reduced incidence of infertility, birth defects, allergic sensitisation, otitis media, pre-eclampsia, metabolic syndrome, high BMI, and non-Hodgkin lymphoma. The current evidence base does not allow a definitive statement on the health benefits of organic dietary intake. However, a growing number of important findings are being reported from observational research linking demonstrable health benefits with organic food consumption. Future clinical research should focus on using long-term whole-diet substitution with certified organic interventions as this approach is more likely to determine whether or not true measurable health benefits exist.

1. Introduction

The global marketplace of organics has grown rapidly over the last few decades and consumer demand for organic products is increasing globally, with approximately 80 billion Euros ($92 billion USD) spent on organic products annually [ 1 ]. A recent report from the Research Institute of Organic Agriculture (FiBL) and IFOAM Organics International, shows a 14.7% increase in organic farmland from 2014 to 2015, totalling 50.9 million hectares, with Australia having the largest amount of agricultural land at 22.7 million hectares [ 2 ]. Organic food items most often consumed in Europe are organic baby foods followed by organic eggs, fruit and vegetables, then dairy products, with organic dairy reaching market shares of around 10 percent of overall sales in some European countries [ 2 ]. In the United States, fruit and vegetables make up the largest areas of organic food sales, followed by dairy products [ 3 ]. The reasons consumers are increasingly choosing organic over conventional food products are varied, including many reasons beside personal health and wellbeing, such as environmental concerns or animal welfare impact. However, the major determinants behind consumer purchase of organic products, is the belief that organic food is healthier or has a superior nutritional profile [ 4 , 5 , 6 ].

Regular consumers of organic food are most likely to be female, health-conscious, physically active, and in the higher brackets of education and income than their non-organic consuming counterparts [ 7 , 8 ]. They are also more likely to have a higher ratio of plant to animal foods, with a strong relationship between vegetarian/vegan consumers and organic consumption [ 7 , 9 ]. This consumer group generally has an increased wholefood dietary intake, as a result of both the general ethos of organic consumers (i.e., preference over processed/ultra-processed foods), and restricted use of additives in organic processed foods. Diet composition between organic and non-organic consumers may, therefore, be quite different.

The notion that organic food may be healthier has some support. Although there appears to be little variation between organic and conventional food products in terms of macro nutritional value (protein, fat, carbohydrate and dietary fibre), other compositional differences have been demonstrated. These include higher antioxidant concentrations (particularly polyphenols) in organic crops [ 10 ]; increased levels of omega-3 fatty acids in organic dairy products [ 11 , 12 , 13 ]; and improved fatty acid profiles in organic meat products [ 14 , 15 ]. These compositional differences are comprehensively discussed in several recent reviews [ 16 , 17 , 18 , 19 ]. There is preliminary evidence to suggest that these compositional differences may have an effect on plasma levels of certain nutrients including magnesium, fat-soluble micronutrients (α-carotene, β -carotene, lutein, and zeaxanthin), and fatty acids (linoleic, palmitoleic, γ-linolenic, and docosapentaenoic acids) [ 20 ]. Any possible clinical effects of such differences need further investigation.

Likely to be of more importance than compositional differences between the two, is what organic foods do not contain. Organic foods have been shown to have lower levels of toxic metabolites, including heavy metals such as cadmium, and synthetic fertilizer and pesticide residues [ 10 , 17 ]. Consumption of organic foods may also reduce exposure to antibiotic-resistant bacteria [ 19 ].

The long-term safety of pesticide consumption through conventional food production has been questioned, with evidence from long-term cohort studies covering areas ranging from possible neurotoxicity to endocrine disruption [ 21 ]. A number of widely used pesticides have been banned retrospectively only when unexpected negative health impacts have been identified [ 22 , 23 ]. From a regulatory perspective, dietary intake of pesticides is not considered to pose a health risk to consumers as long as individual pesticide concentrations in foods are below the Maximum Residue Level (MRL). Surveys conducted by both the European Food Safety Authority and the United States Department of Agriculture show that the vast majority of foods contained individual pesticide levels below the MRL, at 1.7% and 0.59%, respectively, found to exceed the limits. It was also found that 30.1% and 27.5%, respectively, of food samples analysed contained multiple pesticide residues [ 24 , 25 ]. One of the main criticisms of current regulatory pesticide approval processes is that they do not require safety testing of pesticide mixtures or formulations of pesticides [ 23 , 26 , 27 ]. There is considerable controversy about health risks posed by chronic low-level dietary pesticide exposure [ 28 , 29 , 30 ], and whilst lower levels of pesticide residue excretion is consistently observed during organic diet intakes [ 31 , 32 , 33 , 34 ], there is uncertainty around how this may impact the health of the consumer.

The last systematic review into the effect of organic food consumption on health was conducted by Dangour et al. in 2010 [ 35 ], which was limited to strict inclusion criteria of organic interventions, and Smith-Spangler et al. in 2012 [ 19 ], which contained only minimal focus on the human health effects of organic food, and a broader focus on nutritional content of organically and conventionally grown food and food safety. Although there have been other more recent reviews on the effects of organic diet on broader aspects of health [ 16 , 17 , 18 , 21 ], none have been systematic. The literature has expanded since these earlier systematic reviews, with many cohort and cross-sectional studies being published which compare organic versus conventional dietary intake on a range of health outcomes. Dangour et al. (2010) included 12 reports overall, of which eight were human studies (six clinical trials, one cohort study, 1 cross-section study), and four that reported animal or in vitro research. The Smith-Spangler et al. (2012) report was more comprehensive, including 17 human studies (in addition to 223 studies of comparative nutrient/contaminant profiles).

The present systematic review was designed to assess the breadth of evidence related to human health outcomes when an organic diet is consumed in comparison to its conventional counterpart. This review reports results from 35 studies including both clinical trial and observational research and includes substantially more papers than previous systematic reviews on this topic. This review does not include a comparison of nutritional quality between production types, safety of organic food, or human studies where environmental pesticide exposure is the focus.

2.1. Literature Search

This systematic review has been conducted in accordance with the guidelines of the Preferred Reporting Items of Systematic Reviews and Meta-analysis (PRISMA) statement [ 36 ].

Relevant studies were identified by a systematic search from the Cochrane, MEDLINE, EMBASE, and TOXNET databases for articles published in January 2019. Relevant keywords included terms related to organic dietary intake in combination with words relevant to health outcomes (i.e., asthma, eczema, obesity, diabetes). Search terms were amended slightly for each database. Articles with English titles and abstracts were considered for inclusion. The search strategy was developed by two authors (SM and VV) and was performed by VV in January 2019. Additional publications were identified from the reference lists of obtained articles that were included in the review. Refer to Supplementary Figure S1 (see online Supplementary Material ).

All articles that compared organic versus conventional dietary intake in relation to a direct or an indirect health outcome were included. We did not set out to limit paper inclusion by including a strict definition of organic intake, but accepted all papers that self-identified as representing comparative information on health outcomes from organic versus conventional diets. In doing so, we set out a priori to ensure we obtained a comprehensive snapshot of the available literature in this area.

2.2. Study Eligibility Criteria

2.2.1. population.

Only human feeding studies were included. Studies including infant participants measured from the second trimester of pregnancy were included where the mother gave dietary information during pregnancy.

2.2.2. Intervention

Any clinical trial where organic food items were taken to replace non-organic food items, or observational studies where there was a comparison between organic and non-organic dietary intake were included. This encompassed individual food or drink replacement, through to entire diet substitution. Observational research was accepted where dietary intake was classified according to level of organic food within individual dietary groups or whole diet.

2.2.3. Outcome

Clinical trials were included where they provided comparative results on direct or indirect health outcomes. Cohort studies were included where associations with development of disorder or disease were reported, or if they provided comparisons of biological samples across organic versus conventional dietary intake groups.

2.2.4. Study Designs

Types of studies included were randomised controlled trials (RCT), non-controlled trials, prospective or retrospective cohort studies, case-control studies and cross-sectional studies.

2.2.5. Exclusion Criteria

Articles were excluded if they were not specifically examining the effect of organic dietary intake with conventional dietary intake, or if they did not report on human biomarkers related to health, or disease development. Articles were excluded if they were concerned with occupational exposure to agricultural chemicals or domestic use of pesticides and unrelated to dietary consumption of organic versus non-organic foods.

2.3. Data Extraction

Two reviewers independently reviewed full articles for inclusion based on relevance to the study question and eligibility criteria. One reviewer (VV) extracted data from included studies, which was checked by a separate reviewer (SM). The details are presented in Table 1 and Table 2 , using the following parameters: (i) author and year of publication; (ii) study population including country of origin and key demographic detail; (iii) sample size; (iv) study design and duration of intervention/exposure; (vi) exposure to organic diet and comparator; (vii) outcomes assessed; (viii) results; (ix) organic definition.

Data extraction table—Clinical trials.

Abbreviations: 2-AAS: 2-amino-adipic semialdehyde; AMPA: aminomethylphosphonic acid; BMI: body mass index; C: control group; CKD: chronic kidney disease; Cat: catalase; CS: cabernet sauvignon; DAP: dialkylphosphate; DEP: diethylphosphate; DETP: diethylthiophosphate; DEDTP: diethyldithiophosphate; DMDTP: dimethyldithiophosphate; DMP: dimethylphosphate; DMTP: dimethylthiophosphate; DNA: deoxyribonucleic acid; DXA: dual-energy X-ray absorptiometry; FRAP: ferric reducing ability of plasma; GPx: glutathione peroxidase; GR: glutathione reductase; GSH: glutathione; Hcy: homocysteine; LDL: low density lipoprotein; MDA: malathion; NK: natural killer; NO: non-organic group; O: organic group; OP: organophosphate; ORAC: oxygen radical absorbance capacity; RCT: randomised controlled trial; SOD: superoxide dismutase; TAC: total antioxidant capacity; TAG: triacyglycerol; TBARS: thiobarbituric acid reactive substances; TCPy: 3,5,6-trichloro-2-pyridinol; TE: trolox equivalents; TEAC: trolox equivalents antioxidant capacity; Vit: vitamin; WBC: white blood cell.

Data extraction table - Observational Studies.

Abbreviations: AAR: artficially assisted reproduction; AL: anthroposophic lifestyle; ART: assisted reproductive technology; AMPA: aminomethylphosphonic acid; BMI: body mass index; CL: conventional lifestyle; DAP: dialkylphosphate; DETP: diethylthiophosphate; DMP: dimethylphosphate; DMTP: dimethylthiophosphate; FFQ: food frequency questionnaire; FV: fruits and vegetables; HR: hazard ratio; LOD: limit of detection; NO: non-organic group; O: organic group; OM: otitis media; OS: organic score; PBA: 3-phenoxybenzoic acid; PRBS: pesticide residue burden score; TFA: trans-fatty acid; TVA: trans-vaccenic acid; Vit: vitamin.

2.4. Assessment of Risk of Bias

The Cochrane Risk of Bias Assessment Tool was used to assess likelihood of bias in each clinical trial publication [ 67 ]. The Newcastle–Ottawa Quality Assessment Form for Cohort Studies was used to assess the likelihood of bias in cohort studies, and the Specialist Unit for Review Evidence (SURE) checklist was used for the critical appraisal of cross-sectional studies [ 68 , 69 ]. All assessments were conducted by at least two authors, with differences settled by discussion. Summary tables detailing results of bias assessments are presented in Supplementary Figure S2 .

3.1. Study Selection and Characteristics

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram detailing the article selection process is shown in Figure 1 . Searches identified 4329 potentially relevant articles, of which 4234 were excluded after initial screening of title and/or abstract. The remaining 95 full-text publications were assessed, of which a further 60 publications were excluded.

PRISMA flow diagram of study selection [ 36 ].

Thirty-five papers met the criteria for inclusion in this review. Of these, 15 publications reported on 13 clinical trials—three of which were parallel-arm randomised controlled trials (RCT), with the remaining studies utilising a crossover design. In observational studies, 20 publications reported on 13 cohorts. The studies were all published in English. The majority of the clinical trials were conducted in Europe—Germany (2), Denmark (2), Italy (2), France (1), and Switzerland (1), with other countries including: the United States (2), Turkey (1), Brazil (1), and Australia (1). Observational research studies were on cohorts from the United States, United Kingdom, Norway, France, Denmark, Netherlands, and Sweden.

3.2. Clinical Trials (Single Food/Drink Item Substitution)

Several studies investigated the effect of replacing a single non-organic food or drink item with its organic counterpart. Three of the trials utilised an acute dose setting (red wine, apples or grape juice) in a crossover design [ 40 , 42 , 48 ], while others were based on the daily consumption of the food item (tomatoes and derived purees, carrots or apples) for a period of 2–4 weeks [ 37 , 38 , 39 ]. Those studies looking at nutrient levels (i.e., carotenoids, polyphenols) [ 37 , 38 , 39 ] in biological samples (blood or urine), did not find any significant differences in the levels of these markers as a result of the organic intervention.

Other single-item substitution studies measured antioxidant capacity, or DNA damage in biological samples [ 38 , 39 , 40 , 42 , 48 ]. There were no significant between-group differences in these biomarkers in any of the studies.

3.3. Clinical Trials (Whole Diet Substitution)

Eight crossover trials (reported in nine publications) investigated the effect of whole diet replacement from conventional to organic (or at least >80% in one study) for a time period ranging from 4 or 5 days in children [ 31 , 43 , 44 ] to up to 22 days in adult populations [ 34 , 41 , 45 , 46 , 47 , 49 ].

Four of these trials (two in children and two in adults) measured changes in pesticide excretion through urine [ 31 , 34 , 43 , 44 , 49 ]. All of these trials demonstrated a significant difference in the amount of pesticide metabolites excreted during the different phases of the diet interventions. The reduction was, in most cases, dramatic (up to 90% reduction during organic phase) and occurred within a short time frame of only a few days.

The remaining trials were all conducted in adult populations and measured antioxidant capacity and flavonoid excretion [ 41 ]; carotenoids [ 47 ]; or antioxidant capacity, changes to body composition, lipids and inflammatory markers [ 45 , 46 ].

Similar to the results from clinical trials replacing single food items, individual flavonoid and carotenoid excretion appeared to reflect the content of the foods consumed (i.e., a higher quercetin, carotenoid and kaempferol level was shown in organic produce in comparison to conventional produce given as part of the diets, and this was reflected in the urinary output) [ 41 , 47 ].

Two studies completed by the same research group in Italy looked at the effects of a Mediterranean diet intervention (non-organic phase followed by organic phase). An initial pilot study of 10 people [ 45 ] and a following larger cohort study of 150 people (100 healthy and 50 with chronic kidney disease (CKD)) [ 46 ] provided a two-stage intervention, with a controlled Mediterranean diet (MD) for 14 days followed by the same diet for a further 14 days using organic rather than conventional foodstuffs.

The pilot study found an increased antioxidant effect (from 2.25 to 2.75 mM trolox equivalents) after 14 days MD and after 14 days organic MD, respectively, with no baseline measure provided. The authors also showed a generally higher antioxidant level in the organic foods eaten in comparison to non-organic. In the larger study, in both healthy and CKD patients there was a highly significant effect on body weight reduction and improved body composition seen through dual-energy X-ray absorptiometry (DXA) and bio-impedance analysis (BIA) between the two time points (end of conventional MD and end of organic MD). Inflammatory markers (hs-CRP, IL-1, IL-6, IFN-γ and homocysteine) all showed a statistically significant decrease between the same time-points for the healthy group, whilst only hs-CRP and homocysteine were significantly decreased in the CKD group.

3.4. Observational cohort studies

From a total of 20 publications including 13 cohorts, seven prospective cohorts were identified, with the majority involving mother/child pairs. These included the Norwegian Mother and Child Cohort Study [ 55 , 56 ]; KOALA Birth Cohort [ 58 , 59 , 60 ]; ALLADIN study [ 61 ]; PELAIGE Mother–Child Cohort [ 62 ] and the EARTH study [ 52 ]. Two adult-only cohorts involved development of cancer incidence in the Million Women Study [ 65 ], and self-reported health factors in the Nutri-Net Santé Cohort Study [ 20 , 53 , 63 , 64 ]. A retrospective case-control study in a mother–child cohort was also included [ 57 ].

Several of the identified studies provided cross-section data only. These include comparisons of organic and conventional diets on sperm quality/content [ 50 , 51 ]; breast milk composition [ 66 ]; and urinary pesticide excretion [ 32 , 33 ].

For ease of reporting, all of the observational studies have been separated into subject areas. Firstly, looking at potential influence on foetal development (effect on sperm, fertility, and birth defects, pre-eclampsia); breast milk studies; development of allergies in children; urinary pesticide excretion; cancer development incidence; and changes in nutritional biomarkers in adults.

3.4.1. Sperm and Fertility

Two investigations examined the association between sperm health in Danish organic farmers. The first compares the organic farmers to non-organic farmers and shows a significantly lower proportion of morphologically normal spermatozoa in the non-organic group, but no significant difference in relation to 14 other semen parameters [ 51 ]. The other compares the organic farmers to a control group of airline pilots, finding a higher sperm concentration among organic farmers (increased by 43.1%, 95% CI 3.2 to 98.8%), with no differences seen in seminal volume, total sperm count, and sperm morphology [ 50 ].

The Environment and Reproductive Health (EARTH) study examined associations between high or low dietary pesticide exposure in a group of women using assisted reproduction technology (ART) at the Massachusetts General Hospital Fertility Center [ 52 ]. They compared pregnancy/birth outcomes from 325 women (contributing 541 ART cycles) against a dietary pesticide score. They found high-pesticide residue fruit and vegetable (FV) intake was inversely associated with probability of clinical pregnancy and live birth per initiated cycle. Compared with women in the lowest quartile of high-pesticide residue FV intake (<1 serving/day), women in the highest quartile (≥2.3 servings/day) had 18% (95%CI 5%–30%) lower probability of clinical pregnancy and 26% (95%CI 13%–37%) lower probability of live birth. High-pesticide residue FV intake was positively associated with probability of total pregnancy loss.

3.4.2. Mother–Child cohorts

The Norwegian Mother and Child Cohort Study (MoBa) investigated associations between an organic diet and conventional diet during pregnancy and the development of pregnancy complications, including pre-eclampsia [ 56 ] and incidence of the rare reproductive abnormalities in infant boys—hypospadias or cryptorchidism [ 55 ]. Women who reported to have eaten organic vegetables ‘often’ or ‘mostly’ ( n = 2493, 8.8% of study-sample) were found to have a lower risk of pre-eclampsia than those who reported ‘never/rarely’ or ‘sometimes’ (OR = 0.76, 95%CI 0.61, 0.96). A lower prevalence of hypospadias with any organic consumption, in particular organic vegetables, was found, with no difference for cryptorchidism. This prospective study included 35,107 mothers of male infants in Norway, with organic food in six food groups assessed by food frequency questionnaires (FFQ) [ 55 ]. Whole diet composition was considered using slightly different methods in each of these analyses; therefore, residual confounding may exist between the results reported. In a smaller case-control study, retrospective data were collected from mothers of 306 infant males who were operated on for hypospadias matched to 306 mothers of healthy infant males in Denmark. No difference was found for total organic consumption, but increased odds for hypospadias were found specifically when non-organic milk/dairy consumption was combined with frequent consumption of high-fat dairy products (adjusted OR = 2.18, 95%CI 1.09, 4.36) [ 57 ].

The PELAIGE study in France ( n = 1505) was a prospective cohort study that examined the incidence of otitis media during early childhood, finding frequent intake of organic diet during pregnancy was associated with decreased risk of having at least one episode of otitis media (OR = 0.69, 95%CI 0.47, 1.00) [ 62 ]. A sub-group analysis measuring pesticide residues in urine, found the presence of dealkylated triazine metabolites was positively associated with recurrent otitis media (OR = 2.12, 95%CI 1.01, 4.47).

The influence of organic food consumption as part of an anthroposophical lifestyle in pregnancy and early childhood has been discussed following two major studies—the KOALA birth cohort in the Netherlands [ 60 , 70 , 71 ], and the ALADDIN birth cohort in Sweden [ 61 ]. In the KOALA cohort ( n = 2764), consumption of organic dairy products was associated with lower eczema risk (OR = 0.64, 95%CI 0.44, 0.93), but there was no association for other food types or overall organic content of diet with the development of eczema, wheeze or atopic sensitisation. No statistically significant associations were observed between organic food consumption and recurrent wheeze (OR = 0.51, 95%CI 0.26, 0.99) during the first 2 years of life [ 60 ]. In the ALADDIN study ( n = 330), a markedly decreased risk of sensitisation during the first 2 years of life was seen in children of anthroposophic families compared with children of non-anthroposophic families with adjusted OR of 0.25 (95%CI 0.10, 0.64, p = 0.004) [ 61 ].

It is important to note that organic food consumption is only one of several food-specific differences that are a key part of the anthroposophic lifestyle (see discussion).

3.4.3. Early Childhood

Minimal changes were seen in breastmilk composition in the KOALA birth cohort study, with increased rumenic acid and a trend for increased trans-vaccenic acid in quartiles of highest organic consumption [ 58 ]. No difference was seen in trans fatty acid content within the same cohort [ 60 ]. An American study examining milk and urine samples of lactating women for glyphosate and aminomethylphosphonic acid (AMPA) did not find any evidence of these chemicals in the breast milk of conventional or organic food consumers [ 66 ].

Similar to the findings in urinary output of pesticides found in clinical trial research, cross-sectional analysis of organophosphorus metabolites in children ( n = 39) show that those consuming organic foods have considerably lower levels of dimethyl metabolites in their urine than those consuming conventional diets (0.03 and 0.17 μmol/L, p < 0.001), respectively [ 33 ].

3.4.4. Adult Research

The Nutri-Net Santé Cohort has analysed data from 62,224 participants enrolled in France, through an internet-based survey, with information on frequency of organic food consumption and repeated anthropometric data. The data was predominantly self-reported. An increase in the organic score was associated with a lower risk of being overweight (OR = 0.77, 95%CI 0.68, 0.86, p < 0.0001). The association remained strong and highly significant, with a reduction in the risk of obesity of 37% after a 3.1-year follow-up [ 63 ]. A cross-section of the cohort ( n = 8174) examined for metabolic syndrome also detailed positive impact of an organic diet with an adjusted prevalence ratio of 0.69 (95%CI 0.61, 0.78) when comparing the third tertile of organic food in the diet with the first one ( p < 0.0001) [ 64 ]. Additionally, a nested case-control study ( n = 300) evaluated pesticide metabolites excreted in the urine within the group, finding significantly lower levels of pesticide metabolites among organic consumers versus conventional consumers, with median concentration levels of investigated metabolites for diethylphosphate (0.196 versus 0.297), dimethylphosphate (0.620 versus 1.382), and total dialkylphosphates (0.12 versus 0.16), p < 0.05 [ 54 ].

A separate prospective cohort study in adults that estimated organophosphate exposure from food frequency records of 4466 multi-ethnic older Americans, measured urinary pesticide excretion in a sub-group ( n = 240) and found that higher levels of estimated dietary organophosphate exposure were associated with higher dialkylphosphate concentrations excreted in the urine ( p < 0.05) [ 32 ].

The Million Women Study in the United Kingdom examined any association with cancer incidence and organic diet over a 9-year follow-up period in 1.3 million women. They found no association for reduced cancer incidence in the group, with the exception of a possibly lower incidence of non-Hodgkin lymphoma [ 65 ].

The Nutri-Net Santé group also investigated associations with cancer incidence in a cohort of 68,946 participants [ 53 ]. The group, followed for a mean of 4.6 years, report that after adjustment for confounders, high organic food scores were linearly and negatively associated with the overall risk of cancer (HR for Q4 vs Q1, 0.75; 95%CI, 0.63–0.88; p for trend = 0.001; absolute risk reduction, 0.6%; HR for a 5-point increase, 0.92; 95%CI 0.88–0.96). Amongst specific cancers, they found a decreased risk of developing non-Hodgkin lymphoma ( p = 0.049) and postmenopausal breast cancer, with no association for other types of cancer. The information on non-Hodgkin lymphoma is similar to that found in the Million Women study; however, the information related to breast cancer was in direct contrast.

A nested matched case-control study of 300 participants (150 low and 150 high organic food consumers) within the Nutri-Net Santé had serum samples analysed for differences in nutritional biomarkers [ 20 ]. No significant differences were found between the 2 groups for α-tocopherol and retinol, cadmium, copper, ferritin or transferrin. Organic consumers exhibited higher plasma concentrations of α-carotene, β -carotene, lutein, and zeaxanthin, whereas no differences were found for other carotenoids ( β -cryptoxanthin and lycopene). Organic consumers had higher levels of magnesium and a lower plasma concentration of iron. Within the fatty acid analysis, organic consumers had lower palmitoleic acid, γ-linolenic acid, and docosapentaenoic acid and higher linoleic acid concentrations. The results of these participants, matched for dietary patterns and other health factors, indicates a possible mild modulation of nutritional levels between organic and non-organic consumers.

3.5. Bias Assessments

The results of bias assessment for cohort studies showed all studies as good or fair, with no studies returning an assessment of poor. Cross-sectional studies were assessed as having a low risk of bias, with the exception of Jensen et al. (1996), which was a short report, with high bias due to missing detail. Within the clinical trials reviewed, the risk of bias was classified as high in several areas, specifically those related to blinding and allocation concealment. Due to the nature of the intervention, in some cases, it was difficult to adequately blind participants (i.e., food packaging, replacement of ‘usual’ diet products). There were, however, several studies [ 37 , 38 , 39 , 40 , 41 ] where blinding and randomisation is stated, but the method is not adequately reported and, therefore, they have received an unclear risk of bias in these areas. Many of the studies were not randomised, providing one diet followed by the alternate diet for all participants concurrently.

Significant bias likely to affect the outcomes of the reports was found for two studies conducted by the same research group in Italy [ 45 , 46 ]. In both cases, all participants received a controlled Mediterranean diet (MD) for 14 days followed by the same diet for a further 14 days using organic rather than conventional foodstuffs, with no washout between diet arms. This introduces a significant risk of bias for the validity of the outcomes for the organic diet intervention as it may be a cumulative effect of the MD changes, rather than a specific effect for the organic component of the diet.

Another study with high risk of bias was the study by Goen et al. [ 49 ] as it contained only two people in the treatment group, in an open-label crossover trial, with no washout between diets. Results of bias assessments are shown in Supplementary Figure S2 .

3.6. Quality of included Reviews

No formal grading system was applied to the included articles; however, elements of study quality, including high risk of bias or un-realistic results have been discussed for individual articles throughout the review. Several included articles in this present review were not accepted in the previous systematic review into this topic conducted by Dangour et al. (2010). These include pesticide excretion studies [ 33 , 72 ] and a cross-sectional study on semen analyses [ 51 ], excluded on the basis of being contaminant studies; and a second semen analysis study [ 73 ], excluded as an occupational health study. The rationale for our inclusion of these studies is that although occupational exposure may have been a factor in the Larsen study [ 73 ], the method of calculating pesticide exposure was based entirely on food intake. Pesticide excretion studies were included as this was considered potentially important for health, and these studies are also included in other reviews discussing comparison of organic and conventional food intakes on health, i.e., Smith-Spangler et al. [ 19 ].

4. Discussion

This systematic review reports on a wide range of interventional (15 publications) and observational studies (20 publications/13 cohorts), where the health effects of organic diet consumption (whole diet or partial replacement) are compared to conventional diet consumption. Substantially more papers are included compared to previous systematic reviews on this topic [ 19 , 35 ] with varying levels of bias and quality.

4.1. Clinical Trials

The included clinical trials use a diverse range of methodologies, all involving short-term food substitutions. These range from acute intake of a single dietary item (conventional or organic), to entire diet substitution over a maximum exposure time of 4 weeks, with most of the studies utilising a 2-week intervention period. The majority of the results show no, or minimal, significant differences between organic (O) and non-organic (NO) treatments in the biomarkers selected. In several of these trials, a single food or drink [ 37 , 38 , 39 , 40 , 42 , 47 , 48 ] was substituted for their organic equivalent. Those studies that also compared the composition of the two food items found there was no difference in the concentration of the nutrient of interest (i.e., lycopene) between O and NO foods [ 37 , 38 , 47 ]. It seems logical, therefore, that a change in participants’ samples would seem unlikely unless there was positive laboratory evidence to demonstrate a specific difference between the NO and O substance that could lead to a biologically plausible difference in vivo.

Similarly, in whole-diet substitution studies, those that examined antioxidant capacity or nutrients in biomarkers, generally did not show between-group differences, which again appeared to be reflective of the laboratory values of these nutrients were measured [ 41 , 47 ]. However, one study did show a significant change in antioxidant capacity [ 45 ]. This study, and a related trial [ 46 ], which was the only trial to assess a direct health outcome, both provided a NO Mediterranean diet intervention for 2 weeks prior to 2 weeks of the same O Mediterranean diet. There are several issues with the methodology of this model, these and the associated high risk of bias are discussed further in Section 3.5 . The reported weight loss and body composition changes in this study appear unrealistic for the 14-day time frame. The authors report a mean weight loss of 5.6 kg, with mean (SD) weight change from the end of NO diet to end of O diet was 85.17 (±13.97) to 79.52 (±10.41), p = 0.0365. The fat loss is reported as 7.18 kg over the two week period from 23.36 (±8.88) to 16.18 (±3.34), p = 0.0054, there was also a non-significant 1.18 kg rise in lean muscle mass, from 53.45 (±6.69) to 54.63 (±6.76) [ 46 ]. Without baseline assessments provided before any dietary intervention in this group, the effect of the organic intervention cannot be relied upon.

Whole-diet substitution trials that measured changes in pesticide excretion showed significant and substantial reductions during the O diet phase [ 31 , 34 , 43 , 44 , 49 ], and are discussed under Section 4.3 .

To date, there are no long-term clinical trials measuring direct health outcomes from organic diet intervention. The short timeframe of currently available clinical trials is a serious limitation in assessing demonstrable health benefits. Additionally, only surrogate markers of health have been applied to the majority of clinical trials, with most trials measuring antioxidant levels or pesticide metabolite excretion.

4.2. Observational Research

Observational research, which has followed cohorts for up to 10 years (Nutri-Net Santé and the Million Women study), has investigated a range of hypotheses regarding organic diet and health. Studies included in this review report positive associations between organic diet consumption and a range of areas, including fertility, birth defects, allergic sensitisation, non-Hodgkin lymphoma and metabolic syndrome.

Findings from two cross-sectional reports on semen parameters detailed mixed findings, and although the majority of tested parameters showed no significant differences, higher sperm concentration in O consumers [ 50 ] and lower normal sperm in NO consumers [ 51 ] offer preliminary data that is worthy of further exploration. In female fertility, very positive associations between low dietary pesticide exposure and successful pregnancy and birth outcomes in women undergoing assisted reproduction have been reported in one study [ 52 ]. Given the declining fertility rates and poorer semen quality being reported worldwide [ 74 ], higher odds of achieving clinical pregnancy and live birth with an organic diet is a significant and important finding. A reduction in risk of birth defects (hypospadias) [ 55 , 57 ], but not cryptorchidism [ 55 ], and reduced risk of pre-eclampsia [ 56 ] add further evidence for organic diet use through pregnancy.

In children, increased risk of recurrent otitis media has been positively associated with pesticide intake [ 62 ], and decreased allergic sensitisation was shown in families following an anthroposophical lifestyle, in comparison to a conventional cohort in the Assessment of Lifestyle and Allergic Disease During Infancy (ALLADIN) study [ 61 ]. Consumption of organic dairy products was associated with lower eczema risk as the only significant positive outcome in a similar study (KOALA) [ 60 , 70 , 71 ]. There are other studies that have supported lower rates of allergic sensitisation from an anthroposophical lifestyle; however, the contribution of organic foods in these studies was not sufficient for them to be included in this review [ 75 , 76 , 77 ]. Specific confounding factors related to anthroposophic studies are discussed in Section 4.4 .

The largest studies reporting on adult populations include the Nutri-Net Santé Cohort Study (France), and the Million Women Study (UK). Both of these studies have investigated associations with cancer risk [ 64 , 65 ], with both finding reduced risk of developing non-Hodgkin lymphoma with increased organic consumption. Other findings between the two studies were similar, with a very small risk reduction (0.6%) for all cancers in France, but no risk reduction in the UK. Postmenopausal breast cancer rates were decreased in high-O consumers [ 64 ], but overall breast cancer risk slightly increased in the alternate study [ 65 ]. Different adjustment variables between the studies may have been partly responsible for the different outcomes reported, i.e., the Million Women Study adjusted for hormone replacement in breast cancer, which the Nutri-Net Santé study did not report.

Other findings from the Nutri-Net Santé study show reductions in overweight and risk of obesity, as well as reduced incidence of metabolic syndrome demonstrated in favor of organic food intake [ 63 , 64 ]. Whilst this was self-reported data, there is evidence from other association studies that supports dysregulation of several key facets involved in metabolic syndrome in association with serum pesticides [ 78 , 79 ].

As with any observational studies, there is difficulty in determining the causality of the associations that have been observed. It is possible that the benefits of organic diets are associated only with long-term consumption, or result from lifestyle factors or dietary patterns, which is much harder to model in prospective clinical trials.

4.3. Pesticide Excretion

One of the major benefits proposed for organic food is the reduction in exposure to chemicals such as pesticides. Pesticide residues are found in differing amounts across predominantly, fruits and vegetables, but also, grain and dairy products, with much lower amounts found in animal products (except liver, which contains high levels) [ 24 ].

The major class of pesticides tested for in the organic food literature reviewed for this paper were the organophosphates, the metabolites of which can be measured in the urine as markers of recent exposure. The most commonly detected metabolites are dimethylphosphate, dimethylthiophosphate, diethylphosphate, and diethylthiophosphate. In some studies, herbicide exposure was also assessed, mainly glyphosate, often assessed through its metabolite aminomethylphosphonic acid. Interventions with organic diets markedly reduced the levels of these compounds, and observational studies in adults and children also show reduced urinary metabolite levels in organic versus conventional diets.

Given that several organophosphorus (OP) insecticides and glyphosate (an OP herbicide and the world’s most widely used agricultural chemical) were recently re-classified by the WHO’s International Agency for Research on Cancer (IARC) as being “probably carcinogenic” [ 80 ], reduced exposure may potentially benefit health. Results of recent reviews comparing pesticide residues in organic and conventional foods conclude that organic food consumption is one approach to substantially minimise exposure to pesticides [ 17 , 21 ].

The impact of switching to organic food consumption on reducing dietary pesticide exposure may be higher in consumers that follow current dietary guidelines for wholegrain and fruit/vegetable consumption. Foods may also be ‘pesticide-free’ but not ‘organic’. It is well documented that pesticide concentrations in wholegrain and wholemeal products are higher than in polished grains such as white flour products (since the outer bran layers of grains have higher pesticide loads then the endosperm) [ 81 ]. Apart from wholegrain products, fruits and vegetables are the main dietary source for pesticide exposure and recent European monitoring showed that multiple residues and concentrations above the MRL are most frequently found in fruit and vegetables [ 24 ].

4.4. Confounders of Results

Lifestyle factors amongst organic consumers are likely to have an important impact on external validity. Organic consumers tend to be more health conscious, are more likely to be vegetarian or vegan and are more likely to be physically active [ 7 , 8 ].

Epidemiological research has shown consumers of organic food generally have a diet that is higher in plant-based food, lower in animal products, with a higher intake of legumes, nuts, and wholegrains than their conventional food-consuming counterparts. These dietary patterns are likely to have significant health benefits in comparison to what is commonly recognised as the standard Western diet, a diet categorised by highly refined, low-fibre, omnivorous diets low in fruits, vegetables and other plant-based foods [ 82 ]. A wholefood diet (high in fibre and plant matter) also has demonstrable effects on a healthy diverse microbiota, which is linked to overall health [ 83 ]. The organic consumer group may, therefore, not be representative of the general population, i.e., any benefits from organic food consumption may be attributable partly to increased wholefood intake and a healthier lifestyle.

Whole diet composition and diet quality have been measured and adjusted for in different ways in observational research, with varying elements of the diet included as part of the ‘organic intake’ data collected. It is possible that the benefit observed for organic intake may be partly due to the quality and composition of the diet rather than a direct effect of organic food consumption. Additionally, validation of self-reported organic intake in observational studies is lacking.

The included cohorts from anthroposophical backgrounds (ALLADIN and KOALA birth cohorts) adds an additional layer of confounding, as the consumption of organic food forms only a small part of the dietary measures adopted in this group. Anthroposophy includes a strong focus on fermented foods, biodynamic production, use of butter and olive oil as predominant fats, and long-term breastfeeding [ 60 , 61 ]. This is combined with other factors such as reduced levels of antibiotic and medication use and a high proportion of plant foods, which together may impact on the overall health of mothers and babies, and influence the results shown.

4.5. Limitations

In the included studies, there was wide heterogeneity in the definition and application of the term ‘organic’ and the percentage of organic food replacement in the diet. This makes any interpretation on the benefits or otherwise of organic food consumption very difficult. No formal grading system was applied to the included studies. A grading criteria, such as that employed by Dangour et al. (2010), would have been helpful to categorise the research according to quality. The review was limited by the non-inclusion of foreign language databases.

5. Conclusions

A growing number of important findings are being reported from observational research linking demonstrable health benefits to levels of organic food consumption. Clinical trial research has been short-term and measured largely surrogate markers with limited positive results.

Pesticide excretion studies have consistently shown a reduction in urinary pesticide metabolites with an organic diet; however, there is insufficient evidence to show translation into clinically relevant and meaningful health outcomes. There is a need for studies to move beyond simply measuring the reduction in pesticide exposure with organic food, to investigating measurable health benefits.

The finding that organic food consumption substantially reduces urinary OP levels is important information for consumers, who would like to take a precautionary approach and minimise OP-pesticide exposure. Given the current knowledge on the toxicity of these chemicals, it seems possible that ongoing reduced exposure may translate to health benefits.

While findings from this systematic review showed significant positive outcomes from observational studies in several areas, including reduced incidence of metabolic syndrome, high BMI, non-Hodgkin lymphoma, infertility, birth defects, allergic sensitisation, otitis media and pre-eclampsia, the current evidence base does not allow a definitive statement on the long-term health benefits of organic dietary intake. Consumption of organic food is often tied to overall healthier dietary practices and lower levels of overweight and obesity, which are likely to be influential in the results of observational research.

Recommendations for Future Research

Single-food substitution studies have shown no benefits and should not be undertaken without substantive pre-clinical data. Additionally, surrogate markers, i.e., antioxidant levels and pesticide excretion, are insufficient to determine actual benefit to health and ideally should be coupled with measurements related to specific health outcomes. Unlike the current exposure studies which measure changes in days or weeks, longer-term health benefit studies are needed. Specifically, long-term whole-diet substitution studies, using certified organic interventions will provide the most reliable evidence to answer the question of whether an organic diet provides true measurable health benefits.

Additional research options may include further evaluation of biological data collected through previous large cohort studies, such as the Nutri-Net Santé study [ 84 ], and the MoBa biobank [ 85 ], to test hypotheses on organic diet and health.

Supplementary Materials

The following are available online at https://www.mdpi.com/2072-6643/12/1/7/s1 , Figure S1: Medline search strategy, Figure S2: Risk of bias summary tables.

Author Contributions

Conceptualization, S.M. and C.L.; methodology, S.M. and V.V.; data curation, V.V.; writing—original draft preparation, V.V.; S.M.; C.O.; J.A.; S.R.; writing—review and editing, V.V.; C.O. All authors have read and agreed to the published version of the manuscript.

A grant from the Pro Vice-Chancellor (Research) at Southern Cross University partially funded this study.

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Methods on how to lengthen an essay, the benefits of organic food essay sample, example.

Organic foods are believed to be safer than conventional ones, and it has natural origins, which makes it a reasonable choice. According to the requirements of the British Soil Association , organic food should consist of at least 95% natural ingredients (Soil Association). “Natural” means the ingredients should come from the plants and animals grown or bred without any chemicals or artificial nutrients. In the United States, there also exists strict requirements for the products labeled as organic: the U.S. Department of Agriculture has enabled a special certification program that requires organic food to meet specific standards.

In correlation to this, customers should pay attention to the labeling on the packaging of food products. If it says 100% organic , this means the product has been manufactured without the use of any chemicals or artificial additives; simply organic means the product consists of 95% natural ingredients (MayoClinic). Returning to the standards of organic nutrition, organic food cannot contain, in particular, such ingredients as synthetic fertilizers or pesticides; genetically engineered organisms; raw manures cannot be used to fertilize fields as well, because of its potential contamination (Canadian Living). The other 5% of ingredients are allowed as they are not available in organic form, and for non-food ingredients (such as salt, water, and a restricted number of additives like iron or thiamine).

Organic food is known to be healthier than conventional food. According to recent research in the United States, organic food contains an average of 63% more calcium, 73% more iron, 125% more potassium, and 60% more zinc compared to conventional food products. This is not to mention the fact that common food is about 25% more toxic than the food produced from natural components (Canadian Living). Besides, many people claim it tastes better than other products.

Organic products—not only food, but also textiles and cosmetics—are becoming more popular among people globally. Though the price of organic products is often higher than regular ones, its safety, healthiness, and natural origins fully compensate for this disadvantage.

“Facts About Organic Food.” Soil Association. N.p., n.d. Web. 27 Sept. 2013. <http://www.soilassociation.org/whatisorganic/organicfood>.

“5 Organic Food Facts.” Canadian Living. N.p., n.d. Web. 27 Sept. 2013. <http://www.canadianliving.com/food/cooking_school/5_organic_food_facts.php>.

“Organic Foods: Are They Safer? More Nutritious?” Mayo Clinic. Mayo Foundation for Medical Education and Research, 07 Sept. 2012. Web. 27 Sept. 2013. <http://www.mayoclinic.com/health/organic-food/NU00255>.

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Organic food and the impact on human health

Affiliations.

• 1 a Department of Nutrition, Food Sciences and Gastronomy, School of Pharmacy and Food Sciences , University of Barcelona , Barcelona , Spain.
• 2 b CIBER Physiopathology of Obesity and Nutrition (CIBEROBN), Institute of Health Carlos III , Spain.
• 3 c INSA-UB, Nutrition and Food Safety Research Institute, University of Barcelona , Barcelona , Spain.
• PMID: 29190113
• DOI: 10.1080/10408398.2017.1394815

In the last decade, the production and consumption of organic food have increased steadily worldwide, despite the lower productivity of organic crops. Indeed, the population attributes healthier properties to organic food. Although scientific evidence is still scarce, organic agriculture seems to contribute to maintaining an optimal health status and decreases the risk of developing chronic diseases. This may be due to the higher content of bioactive compounds and lower content of unhealthy substances such as cadmium and synthetic fertilizers and pesticides in organic foods of plant origin compared to conventional agricultural products. Thus, large long-term intervention studies are needed to determine whether an organic diet is healthier than a diet including conventionally grown food products. This review provides an update of the present knowledge of the impact of an organic versus a conventional food diet on health.

Keywords: Polyphenols; allergies; cardiovascular; fertility; gut microbiota; pesticides residues.

Publication types

• Comparative Study
• Agriculture / methods
• Antioxidants / analysis
• Cadmium / analysis
• Child, Preschool
• Chronic Disease / prevention & control
• Fertilizers / adverse effects
• Fertilizers / analysis
• Food Microbiology
• Food, Organic* / analysis
• Gastrointestinal Microbiome / physiology
• Health Promotion* / methods
• Health Status*
• Middle Aged
• Nutritive Value
• Organic Agriculture* / methods
• Pesticides / analysis
• Pesticides / toxicity
• Phytochemicals / analysis
• Phytochemicals / pharmacokinetics
• Risk Factors
• Antioxidants
• Fertilizers
• Phytochemicals

Home — Essay Samples — Life — Organic Food

Essays on Organic Food

Writing an essay on organic food is important because it helps spread awareness about the benefits of consuming organic products and the importance of sustainable farming practices.

When choosing a topic for an essay on organic food, consider exploring the health benefits, environmental impact, ethical considerations, and the growing demand for organic products. You can also discuss the challenges faced by organic farmers and the future of the organic food industry.

For an argumentative essay on organic food, you can explore topics such as the health benefits of organic vs. conventional food, the environmental impact of organic farming, and the ethical considerations of consuming organic products.

In a cause and effect essay, you can discuss topics like the impact of pesticides on human health, the effects of organic farming on soil and water quality, and the relationship between organic food consumption and sustainability.

For an opinion essay, you can share your thoughts on the benefits of organic food, the challenges of accessing organic products, and the role of government policies in promoting organic farming.

If you're writing an informative essay, you can explore topics such as the nutritional differences between organic and conventional food, the certification process for organic products, and the history of the organic food movement.

For example, if you're writing an essay on the health benefits of organic food, your thesis statement could be: "Consuming organic food can lead to improved overall health and well-being due to its higher nutrient content and lower exposure to harmful chemicals."

In the paragraph, you can provide a brief overview of the topic and why it's important, as well as a thesis statement that clearly outlines your main argument.

In the paragraph, you can summarize the key points discussed in the essay, restate your thesis statement, and leave the reader with a thought-provoking final statement about the importance of choosing organic food for a healthier, more sustainable future.

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Home / Essay Samples / Food / Organic Food / Why We Need To Eat Organic Foods

Why We Need To Eat Organic Foods

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