Does eating more organic foods reduce the risk of cancer?

According to a prospective population study, the frequent consumption of organic foods was associated with a significantly lower cancer risk in French adults than in adults who had never eaten organic food.

In a sample of 68,946 volunteers, a high organic food score indicating frequent consumption of organic food (quartile 4 or T4) was associated with a 25% reduced cancer risk compared with the lowest frequency of consumption of organic foods. organic food (T1), reported Julia Baudry, PhD, University of Paris and colleagues.

However, the inverse association between frequent organic food consumption and cancer risk was confined to postmenopausal breast cancer and all lymphomas, including non-Hodgkin's lymphoma (NHL), they noted. in JAMA Internal Medicine.

"The standards for organic foods do not allow the use of synthetic fertilizers, pesticides and genetically modified organisms, nor limit the use of veterinary drugs," investigators said. "As a result, organic products are less likely to contain pesticide residues than conventional foods.We have observed a reduction in the risks of specific cancers (postmenopausal breast cancer, NHL … and all lymphomas) among people who consume organic foods more frequently. "

Details of the study

The NutriNet-Health Study is an ongoing website in which researchers are studying the link between nutrition and health. Two months after registration, volunteers were asked to provide information on the frequency of consumption of 16 labeled organic products, including fruits, vegetables, dairy products, meat and fish, cereals, prepared meals , coffee, tea, chocolate, sugar, and dietary supplements.

"The volunteers were asked to provide information on their frequency of consumption of organic products and they could answer:" I consume these foods most of the time, sometimes or never, "Baudry explained in an audio interview. who accompanied the study. "And for these 16 foods, we summarized the responses and provided a score of organic food consumption, after which we examined the association between these scores and the risk of cancer. "The organic food score ranged from zero to 32 points.

The average follow-up of the sample was 4.56 years, during which researchers identified 1,340 cancer cases. The most common cancers were breast cancer (34.3%), prostate cancer (13.4%), melanoma and squamous cell carcinoma (10.1%), and colorectal cancer (7.4%). ), NHL (3.5%) and other lymphomas (1.1%).

After adjusting for confounding factors, the authors reported that the high scores for organic foods were linearly and negatively correlated with overall cancer risk (HR for T4 vs. T1, 0.75, 95% CI 0.63 to 0.88, P= 0.001 for the trend).

However, looking at specific sites, "we found that the negative association was the case for all lymphomas, as well as postmenopausal breast cancer, but we did not find any association with any of these." other cancer sites, "said Baudry. For example, compared to the first quarter, participants in the top quartile of organic food consumption (T4) had a risk of postmenopausal breast cancer reduced by 34% to a CF of 0.66 (95% CI: 0). , 45-.96). P= 0.03).

For the NHL, individuals in the top quartile of organic food consumption had a lower risk of developing this particular lymphoma by 86% with a HR of 0.14 (95% CI: 0.03-0.66) . P= 0.049) while for all lymphomas, people in the top quartile of organic food consumption had a 76% lower risk of developing any type of lymphoma with a CF of 0.24 ( 95% CI: 0.09-0.66, P= 0.02) compared to those of the lower quartile.

The investigators also conducted a sensitivity analysis by including the main determinants of pesticide exposure – ie plant products – in the score of organic foods. They "found no association for postmenopausal breast cancer, but we found that the association remained for all lymphomas," Baudry said.

The results were no longer statistically significant when researchers analyzed the results of different subgroups, such as younger adults, men, those who had only a degree of education. secondary and who had no family history of cancer, smokers never and now, and participants who consumed a high-quality diet. global.

"Promoting the consumption of organic foods in the general population could be a promising preventative strategy against cancer," the authors concluded. However, they recognized that the high cost of organic foods remained a significant barrier to more widespread consumption.

Confusion, conventional vegetables

In an accompanying editorial, Frank B. Hu, MD, PhD, and Jorge E. Chavarro, MD, ScD, both of Harvard TH Chan School of Public Health in Boston, and his colleagues, said that The study presented several strengths, such as the size of its large sample, its prospective plan, and its modest loss in terms of monitoring.

In an audio interview, Chavarro noted that one of the most compelling aspects of the study was the consistency of the study with the results reported by others. For example, in the UK Million Women study, self-reported organic food consumption was associated with a reduced risk of NHL of 21%.

But editorialists also pointed to some weaknesses in the study, such as "the fact that the organic food questionnaire was not validated, so it is not clear what actual exposure was supposed to measure food consumption. It is notoriously difficult to evaluate the biological food intake. , and his self-assessment is very likely to be confused by positive health behaviors and socio-economic factors. "

Chavarro also noted that food labeling, especially in the United States, can be confusing to consumers.

"For example, foods may be labeled" certified organic USDA "," organic "," natural ", made from organic ingredients," no drugs or hormones used ", or" harvested from sustainable way ", so often people think they consume organic products when they are not," he said. MedPage today in an email.

While all organic foods are less contaminated with pesticides and other chemicals than conventionally grown foods, "the benefit in terms of reducing exposure is not the same for all. food, "added Chavarro. For example, differences in pesticide residue contamination between organic and conventional spinach or spinach are much greater than the difference between conventionally grown cantaloupes or avocados, because people do not eat peel or skin products exposed to the pesticide itself. conventionally grown products will have relatively low levels of contamination to begin with.

"Therefore, choosing organic or non-organic foods will not necessarily capture actual exposure to pesticides and other chemicals without knowing the specific foods chosen as organic or conventional products," said Chavarro.

Despite these limitations, "I think the main result of this study is that we should probably pay more attention to this issue than we are," he said.

The Chavarro group suggested that for overall health, the benefits of consumption of conventionally grown produce probably outweigh the potential for pesticide contamination. Indeed, "concerns about the risks of pesticides should not discourage the consumption of conventional fruits and vegetables, especially because organic products are often expensive and inaccessible to many people," they said.

2018-10-22T11: 00: 00-0400