Organic food lowers your pesticide levels within days, but proof of health benefits is still missing

Key takeaways

• In a 2019 study of four U.S. families, six days of all-organic eating cut a breakdown product of the insecticide malathion in their urine by 95%¹.
• A French study of 68,946 adults linked frequent organic eating to 25% fewer cancers, but a British study of 623,080 women found no drop in overall cancer⁴⁶.
• People who buy organic tend to exercise more, eat more plants and eat more whole foods, which makes it hard to give the food itself the credit⁸⁹.
• A 2016 review found organic milk had about 56% more omega-3 fat than conventional milk, but about 74% less iodine¹².
• On a tight budget, put organic dollars toward the foods your household eats most, and never cut back on produce to afford organic¹¹.

For a study published in 2019, four families in Oakland, Minneapolis, Atlanta and Baltimore agreed to change one thing. After several days of eating as usual, they ate only organic food for six days¹².

Researchers tracked pesticide traces in their urine throughout. By the end of the organic week, a breakdown product of the insecticide malathion had fallen 95%¹. A marker of chlorpyrifos, another insecticide, fell about 61%. The neonicotinoid clothianidin fell about 83%¹.

That’s about as clear as nutrition science gets. What you buy changes what your body carries, and fast.

But most shoppers want to know something bigger: does eating organic make you healthier? That second step, from lower levels to fewer illnesses, is where the evidence thins out.

Our organic produce guide covered residues, nutrients and the environment. This one asks about your health, and gives each side its best case.

The short answer: Lower exposure is proven, but better health isn’t

Is organic food healthier? Not in any way science has proven yet. It clearly lowers the pesticides you take in, and for some people that may matter more than for others.

Three major reviews land in roughly the same place:

• A 2019 systematic review pulled together 35 papers on organic eating and human health. Its authors said the evidence does not allow a firm statement about long-term benefits⁸.
• A 2017 review written for the European Parliament said organic food may lower the risk of allergies and of overweight and obesity. It called the evidence not conclusive, because organic eaters tend to live healthier lives in general⁹¹⁰.
• The American academy of Pediatrics (AAP) said in a 2012 clinical report that organic foods have the same nutrients as conventional foods and lower pesticide levels. It found no direct evidence that an organic diet improves long-term health¹¹. We found no newer AAP report on organic food.

None of these reviews says organic food is useless. They say the experiments that would settle the health question haven’t been done.

Many natural-health readers follow a simple rule: when in doubt, keep it out. If you buy organic to put fewer synthetic chemicals on your family’s plate, the evidence backs you. If you buy it expecting less disease, the science hasn’t caught up, in either direction.

Six days of organic food changed what families carried

The family study, led by Carly Hyland at the University of California, Berkeley, tested 16 people and 158 urine samples¹². Thirteen pesticides or their breakdown products dropped significantly on the organic diet¹.

They included three classes of insecticides and the weed killer 2,4-D, which fell 37% in the report released with the study¹³.

Who ran it matters. The environmental group Friends of the Earth carried out the study with university researchers, and research assistants on the project bought the organic groceries and delivered them to families’ homes³. Two foundations, the California Consumer Protection Foundation and the Panta Rhea Foundation, helped pay for the work³. Outside labs at UC San Francisco and a Québec public health institute ran the tests³.

An advocacy group’s role doesn’t make the lab numbers wrong, and other short trials found the same pattern. Across the trials in the 2019 review, pesticide breakdown products fell sharply during organic phases⁸.

The 2017 European review explains why. For most people, the main way pesticides get into the body is through traces left on conventionally grown fruits and vegetables⁹.

This is the catch. None of the trials in the 2019 review measured an actual health outcome⁸. Whether lower levels prevent disease is a separate question.

Two giant cancer studies reached opposite answers

The biggest health claims for organic food come from two long-running studies of everyday eaters.

The French study. NutriNet-Santé followed 68,946 adults, most of them women, for an average of about four and a half years⁴. Researchers scored how often people ate organic versions of 16 kinds of foods⁴.

The quarter with the highest scores had a 25% lower risk of cancer than the quarter with the lowest⁴. The absolute risk reduction was 0.6%⁴. By our math, that’s roughly 6 fewer cancers for every 1,000 people over the study.

Lymphomas, cancers of the immune system, showed the biggest gap⁴⁵. But the result for non-Hodgkin lymphoma rested on just two cases in the top organic group⁴.

A lower risk of breast cancer after menopause also appeared, but it faded when the team used a simpler organic score⁴. The journal later published a correction that reworded the study’s conclusions⁴.

The British study. The Million Women Study, a project of Cancer Research UK and the National Health Service, followed 623,080 middle-aged women for 9.3 years⁶⁷. It recorded 53,769 cancers⁶.

Women were grouped by how often they said they ate organic food. Thirty percent said never, 63% sometimes and only 7% usually or always⁶.

Women who usually or always ate organic had no lower overall cancer risk than women who never did⁶. Their risk of non-Hodgkin lymphoma was 21% lower. Their risk of breast cancer was 9% higher⁶.

The authors concluded that organic eating brought little or no drop in cancer, with a possible exception for lymphoma⁶. The Soil Association, a British organic group, pushed back. Its policy director, Peter Melchett, called it “strange” to brush aside a 21% drop in lymphoma⁷. He also noted that body mass index and exercise were measured only once⁷.

Read side by side, the studies agree on one point: both found fewer lymphomas in organic eaters⁴⁶. That’s the most intriguing thread in this research. On overall cancer and breast cancer, they point in opposite directions.

Why it’s so hard to give the food the credit

People who choose organic food rarely change just one thing. Researchers call this healthy-user bias: the habits that travel with a healthy choice can make the choice itself look more powerful than it is.

Picture two neighbors. One buys organic, walks every morning and cooks beans and greens most nights. The other buys conventional food and lives mostly on takeout. If the first neighbor stays healthier, the organic label is only one of many suspects.

The 2019 review laid out the problem plainly. People who buy organic are more likely to care about health and to exercise. More of them are vegetarian or vegan, and their diets lean toward whole foods⁸. Most studies also relied on people’s own reports of how much organic food they ate, and few checked them⁸.

Scientists try to subtract these differences with statistics. The French team adjusted for social background, lifestyle, eating habits and family history, and said its results held⁵. But you can only adjust for what you measured.

The study that could settle the question would assign thousands of people, by chance, to organic or conventional diets for years. It hasn’t been done, and the 2019 review called for exactly that kind of long-term trial⁸.

Pregnancy, fertility and children show the most intriguing signals

The 2019 review flagged several pregnancy findings, all from studies that observed people rather than testing diets⁸:

• Pre-eclampsia. In a large Norwegian study, women who often ate organic vegetables had lower odds of pre-eclampsia, a dangerous rise in blood pressure during pregnancy⁸.
• Hypospadias. The same cohort found fewer cases of this birth defect, in which the opening of a boy’s urethra forms in the wrong place, among mothers who ate organic food⁸.
• Fertility. Among women in fertility treatment, those who ate produce lower in pesticide residues had better chances of pregnancy and live birth⁸. That study tracked residue levels on produce, not organic buying itself.

Each of these is one study, not a pattern confirmed many times over.

A second line of evidence comes from pesticide research itself. The 2017 European review found that some pesticides have been linked to harm in children’s brain development at the exposure levels people have now⁹¹⁰. Philippe Grandjean, one of its authors, said organic food is one way to lower that risk¹⁰. The review noted that this evidence hasn’t yet been used in official safety reviews of individual pesticides⁹.

The AAP agreed that lower pesticide levels may matter for children. Joel Forman, a lead author of its report, said children are “uniquely vulnerable to chemical exposures“¹¹.

This is where the precautionary instinct many natural-health readers share has its firmest footing. If you’re pregnant, it’s a fair reason to buy some organic food. It’s never a reason to eat fewer fruits and vegetables.

Organic milk and meat: more omega-3, less iodine

A 2016 review in the British Journal of Nutrition drew on 196 publications about milk and dairy¹². Compared with conventional milk, organic milk held about 56% more omega-3 fat and 41% more conjugated linoleic acid, a fat found in dairy¹². It held about 74% less iodine¹².

The authors credited feeding: organic herds spend more time grazing and eat more grass and other forage¹². The European Union and the Sheepdrove Trust paid for the work¹².

How much does that add up to? Ian Givens, a nutrition professor at the University of Reading, pointed out that the 56% applies to milk fat, not whole milk¹³. By his estimate, switching would add about 33 milligrams of omega-3 a day, roughly 1.5% of what a typical diet supplies, which he judged too small to matter for health¹³.

Givens also said grass-rich feeding, not the organic label, drives the difference¹³. A companion review of 67 meat studies found about 47% more omega-3 fat in organic meat¹³. Our fats article explains why fish remains the main omega-3 source.

The iodine gap gets less attention. By the authors’ estimate, half a liter of conventional milk supplies about 88% of the British daily iodine target, while organic milk supplies about 53%¹³. If organic milk is your main dairy, ask a clinician or dietitian whether your diet covers iodine.

Drug-resistant bacteria: organic farming’s clearest public-health case

The strongest health argument for organic meat may have little to do with the person eating it. The 2017 European review called antibiotic use in conventional livestock a key driver of antibiotic resistance across society, and found that organic farms use the drugs less heavily⁹.

A 2011 University of Maryland study tested 10 conventional poultry houses and 10 that had just switched to organic practices¹⁴. It looked for enterococci, common gut bacteria, in litter, feed and water¹⁴.

Bacteria measured	Conventional houses	Newly organic houses
E. faecalis resistant to erythromycin	67%	18%
E. faecalis, multidrug-resistant	42%	10%
E. faecium, multidrug-resistant	84%	17%

The researchers were surprised to see the difference as early as the first flock raised under organic rules¹⁴. The Johns Hopkins Center for a Livable Future funded the study¹⁴.

It was a small study in one region, and it tested farm environments, not packages of meat. The AAP reached a similar view in 2012: organically raised animals are less likely to carry drug-resistant bacteria, it said, because organic rules bar nontherapeutic antibiotic use¹¹.

Both findings come with a date stamp. In January 2017, the FDA announced that drug companies had finished removing growth-promotion uses from the labels of medically important farm antibiotics, under a policy called Guidance for Industry #213¹⁵. Those drugs now need a veterinarian’s order before they go into feed or water¹⁵.

Critics, including a Johns Hopkins researcher, warned that routine doses given to prevent disease were still allowed¹⁵. Even so, conventional farms today may differ from the ones tested in 2011.

So the organic choice here is mostly about which farming system you want to support. Organic or not, handle raw meat with the usual care.

Who gets the most from organic: a decision guide

Your situation	Why organic may matter more, or less	Where to start	Evidence that organic improves health here
Pregnant or trying to conceive	Pregnancy and fertility studies hint at benefits; some insecticides are linked to children’s brain development89	The produce you eat most, and keep eating plenty of it	Promising but early
Feeding babies and young children	Children may be more vulnerable to chemical exposures11	The fruits and vegetables your child eats every day	Not enough evidence
Big produce eaters	Produce residues are the main pesticide source for most people9	Your top three to five fruits and vegetables	Not enough evidence, though the drop in exposure is strong evidence18
Farmworker or farm families	The diet studies tested city families, not exposure from work12	Treat food as one piece; ask a clinician about work exposure	Not enough evidence
Tight budget	The AAP worries families will buy less produce to afford organic11	Conventional produce, washed well	Not enough evidence; eating more produce comes first11

Spend your organic dollars here first

1. The produce your household eats most, especially items eaten raw or with the skin on. Our organic produce guide shows how to check them.
2. Daily staples for a pregnancy or a toddler, such as the fruit your child eats every morning.
3. Meat and poultry, if fighting antibiotic resistance is your priority⁹¹⁴.
4. Milk later, at least for nutrition. The omega-3 gain is small and iodine is lower¹²¹³. Animal welfare or grazing may still be good reasons for you.
5. Organic snacks and sweets last. The label changes how the ingredients were farmed, not the sugar or the refined flour.

For where the price gap is small, see our article on the organic premium.

How strong is the evidence?

Claim	Rating	Why
Eating organic lowers pesticide levels in your body within days	Strong evidence	Consistent drops in short trials18
Eating organic lowers overall cancer risk	Not enough evidence	A French study found fewer cancers; a much larger British study didn’t46
Eating organic lowers lymphoma risk	Promising but early	Both studies saw fewer cases; the French numbers were tiny46
Organic eating in pregnancy lowers pre-eclampsia or birth defects	Promising but early	Single observational findings8
Organic eating lowers allergy or obesity risk	Promising but early	Possible, but tangled with healthier lifestyles9
Organic milk adds a meaningful amount of omega-3 to your diet	Evidence says no, or unsafe	Higher in milk fat, but about 33 milligrams a day1213
Organic poultry farms carry fewer drug-resistant bacteria	Promising but early	One 20-house study from before the 2017 FDA limits; reviews agree on the direction9111415

Questions readers ask

The bottom line

Organic food does one thing reliably: it lowers the pesticides you take in, within days. Whether that lower exposure means less cancer, healthier pregnancies or fewer allergies is still unproven. The studies that hint at benefits are tangled up with the healthier habits of the people who buy organic.

That makes organic a reasonable precaution, not a proven treatment. Put it where it matters most to you, such as pregnancy, young children and the produce you eat every day. Never let its price push fruits and vegetables off your table.

Related reading

• Organic produce has fewer pesticide residues, but the nutrition gap is small
• Where the organic premium is small and where it isn’t
• The four USDA organic labels and what each one promises
• Why observational studies got smoking right and hormone therapy wrong
• Who paid for the study matters, even when the science is real

Sources

1. Hyland C, Bradman A, Gerona R, et al. “Organic diet intervention significantly reduces urinary pesticide levels in U.S. children and adults.” Environmental Research, 2019 (abstract via TABLE research library). tabledebates.org
2. UC Berkeley School of Public Health. “Organic diet intervention significantly reduces urinary pesticide levels in U.S. children and adults.” February 23, 2019. publichealth.berkeley.edu
3. Friends of the Earth U.S. “Organic for All” report and study methods page. 2019. foe.org ; foe.org
4. Baudry J, Assmann KE, Touvier M, et al. “Association of Frequency of Organic Food Consumption With Cancer Risk: Findings From the NutriNet-Santé Prospective Cohort Study.” JAMA Internal Medicine, 2018 (abstract and key points). pubmed.ncbi.nlm.nih.gov
5. Inserm. “Fewer cases of cancer in organic food consumers” (press release). October 2018. presse.inserm.fr
6. Bradbury KE, Balkwill A, Spencer EA, et al. “Organic food consumption and the incidence of cancer in a large prospective study of women in the United Kingdom.” British Journal of Cancer, 2014;110(9):2321–2326. researchportalplus.anu.edu.au
7. FoodNavigator. “‘Strange’: Soil Association gives verdict on Cancer Research UK organic food study.” April 8, 2014. foodnavigator.com
8. Vigar V, Myers S, Oliver C, Arellano J, Robinson S, Leifert C. “A Systematic Review of Organic Versus Conventional Food Consumption: Is There a Measurable Benefit on Human Health?” Nutrients, 2020;12(1):7 (published online December 2019). pubmed.ncbi.nlm.nih.gov
9. Mie A, Andersen HR, Gunnarsson S, et al. “Human health implications of organic food and organic agriculture: a comprehensive review.” Environmental Health, 2017;16:111. cris.maastrichtuniversity.nl
10. European Parliament Scientific Foresight Unit (STOA). “Is organic food really good for our health?” February 13, 2017.
11. MeatPoultry.com. “Pediatrics group gives guidance on organic foods” (on the American Academy of Pediatrics clinical report “Organic Foods: Health and Environmental Advantages and Disadvantages”). October 24, 2012. meatpoultry.com
12. Średnicka-Tober D, Barański M, Seal CJ, et al. “Higher PUFA and n-3 PUFA, conjugated linoleic acid, α-tocopherol and iron, but lower iodine and selenium concentrations in organic milk: a systematic literature review and meta- and redundancy analyses.” British Journal of Nutrition, 2016;115:1043–1060. eprints.soton.ac.uk
13. FoodNavigator. “Organic meat & dairy has more omega-3 but amounts aren’t ‘nutritionally relevant’.” February 16, 2016. foodnavigator.com
14. University of Maryland School of Public Health. “Poultry farms that go organic have significantly fewer antibiotic-resistant bacteria” (on Sapkota AR, Hulet RM, Zhang G, et al., Environmental Health Perspectives, 2011). EurekAlert, August 2011. eurekalert.org
15. Dall C. “Farm antibiotics: Does new FDA policy go far enough?” CIDRAP News, University of Minnesota Center for Infectious Disease Research and Policy, January 2017. cidrap.umn.edu