Are organic foods better for your health? What science really says
Written by Giuseppe Caprotti
Drafted on November 13, updated on November 23, 2024
When, in the 1990s, I began my personal and corporate journey (at Esselunga) toward organic products, Dr. Claudio Arnoldi, the Quality Control Manager, told me that organic food had a primarily environmental value.
Today, 25 years later, there is growing evidence that consuming organic food has a health benefit—and that climate, environment, health, and food are all interconnected. Moreover, there is increasing discussion about an addiction to junk food (ultra-processed food), whose consumption has skyrocketed, leading to cancer, diabetes, and obesity, especially among young people.
For this reason, the Foundation will increasingly offer articles relating to food and health.
Of course, we are aware that organic products represent, given their price, a niche market in Italy (about 3.5% of consumption), but what is not purchased in our country is exported.
Italy stands out among the “most organic” countries in Europe with 2.3 million hectares, after France (2.9 million hectares) and Spain (2.7 million hectares). The Italian organic area represents about one-fifth (19.8%) of the total agricultural land. This means that, thanks to organic farming, one-fifth of Italian agricultural land is free from pesticides.
In essence, organic food is a niche market—which, for various reasons, has not been able to fully express its potential (for example, the percentage of consumption in France is almost double, at 5.6%, compared to Italy)—but it has a strong positive impact on the Italian environment and, therefore, on our health.
Regarding organic food, I also recommend reading this article in which nutritionist Renata Alleva, from the ISDE ITALIA scientific committee, speaks.
For an update on the sector and on how this government is hindering it, read this article.
Are Organic Foods Better for Your Health? What Science Really Says
By Stéphane Foucart
Numerous studies demonstrate the benefits of organic foods, particularly in reducing the risk of certain cancers, overweight, obesity, and congenital malformations. Experts emphasize the overall consistency of these findings, although the number of studies remains too small to establish indisputable causal links.
Is organic food truly better for health? When researchers launched their experiment in 2017, the team from the Chizé Center for Biological Studies (CNRS, University of La Rochelle) and the Biogéosciences Laboratory (CNRS, University of Burgundy) did not intend to answer a public health question, but rather an ecological one. “We wanted to know how environmental contamination by low doses of a mixture of pesticides—that is, what we encounter in agricultural areas—might influence the survival of wild birds such as the grey partridge,” explains biologist and ecologist Jérôme Moreau of the University of La Rochelle. Finding an experimental protocol that mimicked these living conditions, to compare them with a situation in which animals are either unexposed or only minimally exposed, was challenging: we therefore chose to focus on the birds’ food.”
For several months, the researchers raised two groups of grey partridges (Perdix perdix): one group was fed wheat and corn from organic farming, while the other received the same cereals, but produced conventionally. The objective was to observe the impact of trace amounts of synthetic pesticides—banned in organic agriculture—present in the birds’ feed. “Some colleagues told us that we wouldn’t see any effect. On the contrary, the results were surprising and caught us off guard,” says Mr. Moreau.
Within just a few weeks, the “conventional partridges” exhibited a dysregulated immune system compared to the “organic partridges,” a reduced number of red blood cells, and an increased burden of intestinal parasites. Published in 2021 in Environmental Pollution, these findings also showed that conventional females laid smaller eggs with thinner shells; additionally, they accumulated more fat and had a stouter body compared to the “organic” ones. As for the males, their plumage was less vibrant. According to the researchers, these sex-specific effects could be linked to the endocrine-disrupting properties of some pesticides.
Reproductive Effects
Their latest observations, published in 2023, even show that the conventional diet reduces the birds’ flight capacity and vigilance. “The flight initiation distance—that is, the distance at which a partridge flees when an intruder approaches—is about half in conventionally fed birds compared to their organic counterparts,” explains Mr. Moreau, a sign that there are likely repercussions on the birds’ central nervous system.
These results are consistent with other, much older studies on animals. In a 2009 article, Alberta Velimirov (FiBL, Vienna) and her co-authors compiled a body of literature that has since been largely forgotten. They reported that as early as the 1920s, scientists were investigating whether, compared to natural fertilizers, synthetic fertilizers could affect the crops whose growth they promote—and, therefore, those who consume them. Between 1926 and 1987, about a dozen studies on rats, rabbits, chickens, and even cattle were published, most of which showed harmful effects on reproduction, survival, and litter size. In 1965, two German researchers observed that the sperm of bulls fed hay cultivated without synthetic fertilizers had better motility. What were the reasons? Among the explanations proposed today is the presence of certain heavy metals, such as cadmium, in chemical phosphate fertilizers.
Between 1975 and 1992—as recalled by Velimirov and her co-authors, that is, at the beginning of the official specifications for organic agriculture (recognized in France in 1981)—four separate studies were conducted to evaluate the effects of organic food consumption on the reproduction of rodents. All indicated an advantage. In 1989, more than thirty years before Jérôme Moreau and his co-authors made similar observations on partridges, Karin Plochberger (from the Ludwig-Boltzmann Institute for Organic Agriculture) demonstrated that hens fed with organic methods laid larger eggs than those fed conventionally.
For humans, the matter is of course more complicated. We cannot confine individuals to a laboratory for their entire lives, control their diets and activities, monitor their reproductive capacity, and follow their offspring, etc. It is almost always necessary to rely on observational studies, which are inherently more fragile than controlled laboratory work. “The first attempts to evaluate the impact of organic food on health were made using a group of children, some of whom came from families following an ‘anthroposophical’ lifestyle, particularly favoring organic products,” states biochemist and nutritionist Denis Lairon (Inserm), one of the pioneers of organic research in France. This work, published in the mid-2000s, suggests an effect on immunity—specifically a reduced risk of allergies in these children. However, Lairon points out that the evidential value of such observational studies remains “limited.” Despite all these real-life observations, what is truly compelling is the growing number of converging studies.
“A Kind of Misunderstanding”
In the mid-2000s, nutritional epidemiologists began efforts to confirm—or refute—the initial indications. However, the beginnings were not easy. “When we started working on organic products and health, we encountered a kind of misunderstanding, as if it were not a genuine research question,” says Emmanuelle Kesse-Guyot, Director of Research at INRAE and a researcher with the Nutritional Epidemiology Research Team (EREN). Behind this reluctance, the epidemiologist believes, lies the notion that if certain practices or inputs are authorized by regulation, then there is no risk, and thus nothing significant to investigate. However, as Jérôme Moreau asserts, “normative studies only assess the health or environmental effects of pesticides molecule by molecule, without considering the chronic exposure to low doses of these products in mixtures.”
To date, studies aimed at demonstrating the long-term health effects of organic food remain individually rare compared to the hundreds of publications on the effects of dairy products, fruit and vegetable consumption, or processed meats. “The number of available studies is still limited, but the majority indicate benefits,” summarizes Denis Lairon.
The most recent systematic review of the scientific literature on the subject, published in September by Chinese scientists led by Bibo Jiang (Sun Yat-sen University, Guangzhou) in the journal Nutrition Reviews, clearly illustrates the French researcher’s point. The authors analyzed all available scientific literature to evaluate the effects of organic food on human health. They collected fifty published studies. For many conditions or diseases, the observed effect is favorable, but there are too few studies to replicate each result and increase the weight of the evidence.
For example, in a group of pregnant Norwegian women, an organic diet was associated with a reduced risk of preeclampsia (gestational hypertension), but this result has not yet been reproduced by other teams. Likewise, the risk of giving birth to a child with hypospadias (a penile malformation) is reduced among women who consume more organic foods, yet only two studies have reached this conclusion. Similarly, two Scandinavian studies suggest that organic food improves sperm quality. Cancer? Two studies indicate a reduced risk of certain lymphomas. The picture is similar for allergies, which were reduced in two studies on children—though other, more recent works on this topic (too recent to have been included in the synthesis by Mr. Jiang and his colleagues) have found no effect.
“Weighted Evidence”
The Chinese researchers developed a “weight” scale for the evidence: for each disease or disorder investigated, they required that at least four studies be available and that more than 60% of them conclude a beneficial effect before considering the level of evidence to be satisfactory. On this scale, the reduction in weight gain and obesity risk appear to be the best-supported effects of organic food: four different studies all reached the same conclusion.
“If there are still few studies available, it’s because it is very difficult to precisely assess the nature and proportion of organic food consumed within a group,” explains Ms. Kesse-Guyot. Among all the epidemiological studies published on the subject, the work from the EREN team, conducted on the NutriNet cohort, stands out for the precision of the dietary information collected on the 70,000 individuals followed and for the careful consideration of confounding factors (socio-professional category, tobacco and alcohol consumption, physical activity, etc.).
A significant part of our current understanding of the effects of organic food comes from this group. An article published in 2022 in Advances in Nutrition, signed by the twenty researchers involved, summarizes their findings: “Regular consumption of organically grown foods is associated with a reduced risk of obesity, type 2 diabetes, postmenopausal breast cancer, and lymphoma,” they write. Although many of these observations have been confirmed by other studies conducted in different countries, our results need to be replicated in other contexts and paired with experimental studies to establish a causal link.
In some cases, experimental studies have been conducted specifically to validate the plausibility of a causal relationship. Researchers from the Toxalim unit (INRAE) exposed mice for fifty-two weeks to a mixture of six synthetic pesticides frequently found in conventionally grown fruits and vegetables, at doses low enough to simulate consumer exposure. As a result (published in 2018 in Environmental Health Perspectives), the treated male mice doubled their weight gain during the experiment compared to unexposed mice, and after four months developed glucose intolerance—a potential early sign of type 2 diabetes in humans.
Loss of IQ Points
Researchers studying the health effects of organic food emphasize the overall consistency of the available results. In 2018, early findings from the NutriNet cohort on cancer links, published in JAMA Internal Medicine, showed, for example, an association with non-Hodgkin lymphoma: the one-quarter of the cohort that most frequently consumes organic products had an 85% lower risk of developing this disease compared to those following an exclusively conventional diet. However, Ms. Kesse-Guyot notes, “these are the cancers for which we hardly know any other risk factors besides chemical contaminants.” It is also the first type of cancer to have been recognized as an occupational disease among farmers exposed to pesticides in the course of their work.
Another British study, published in 2014, indicated about a 20% reduction in lymphomas among habitual organic consumers compared to those who consume little or none. Yet another study, published in 2023, found an inverse association in a Danish cohort.
“There is another way to estimate the benefits of organic food, namely by evaluating the impact of synthetic pesticide residues in the diet,” explains Denis Lairon. One thing is certain: organic eating dramatically reduces exposure to these substances. In their literature synthesis, the Chinese researchers identified 16 studies on the topic—15 of which clearly demonstrate that the levels of pesticides in blood or urine decrease with the adoption of an organic diet.
The health effects of pesticides in the general population are rare, but they do exist. In 2015, an international team estimated that exposure to organophosphate pesticides—especially maternal exposure during pregnancy—resulted in an average loss of 2.5 IQ points for a child born in Europe in 2010. The authors estimated that approximately 60,000 cases of mental retardation in Europe each year are attributable to this single family of pesticides, whose use is banned in organic agriculture.
More recent studies have focused on the excess mortality potentially linked to residues of plant protection products in food. The authors, led by Helena Sandoval Insausti and Jorge Chavarro (Department of Nutrition, Harvard University), analyzed data from three cohorts totaling more than 160,000 people followed over two decades, whose dietary habits were assessed. Their initial finding was that individuals consuming more than four servings per day of fruits and vegetables that were slightly or moderately contaminated saw their mortality from cancer, cardiovascular, or respiratory diseases reduced by an average of 36% over the study period, compared to those who consumed less than one serving per day of similarly contaminated produce.
However, when fruits and vegetables were classified into two groups—the most contaminated and the least contaminated—the researchers observed that consuming four daily servings of the most contaminated items did not reduce mortality. They concluded that the deleterious impact of the residues seems to have offset the benefits of fruits and vegetables. “This is significant work,” asserts Denis Lairon, not only for its statistical power but also for the expertise of its authors, who have produced internationally recognized studies.
Another striking conclusion reached by these researchers is that, in a given population, replacing a single daily serving of highly contaminated fruits and vegetables with a serving of less contaminated ones would reduce mortality by about 11%! Using the same methodology, the same team was able in May 2022 to highlight a possible link between lower pesticide residue levels and a reduced risk of glioma.
Since 2019, the National Nutrition and Health Program has recommended “switching to organic,” recalls its former president, Serge Hercberg, one of the leading figures in nutritional epidemiology in France. “As part of a scientific approach, the level of evidence for the beneficial effects of organic food is limited, but we have also taken into account the aspects of planetary health in our recommendation,” says Hercberg—a position reached by consensus.
