(Reuters Health) - People who eat more organic foods may be slightly less likely to develop certain cancers, a French study suggests.

Compared to people who consumed the least amount of organic foods, people who consumed the most were 25 percent less likely to develop cancer during the study. In absolute terms, this translated into about a 0.6 percent lower risk of cancer.

“It has to be born in mind that an overall healthy nutritionally diet (rich in fruit and vegetables etc.), whatever the farming system (organic or conventional), as well as high physical activity are important documented protective factors against certain cancers and other diseases,” said lead study author Julia Baudry of the French Institute of Health and Medical Research INSERM in Paris.

An observational study like this one can’t prove that eating organic foods causes fewer cancers, but the results suggest that an organic-based diet could contribute to reduced cancer risk, Baudry said by email.

Organic food standards don’t allow the use of synthetic fertilizers, pesticides, and genetically modified organisms and restrict the use of veterinary medications like antibiotics.

Although some previous research suggests that agricultural chemicals may be linked with certain cancers, researchers don’t have a clear picture of whether organic foods free of these chemicals can help lower the risk of cancer.

In the current study, reported in JAMA Internal Medicine, almost 69,000 adults completed web-based questionnaires about their diets over three 24-hour periods.

Researchers focused on 16 types of organic products: fruits; vegetables; soy-based products; dairy; meat and fish; eggs; grains and legumes; bread and cereals; flour; vegetable oils and condiments; ready-to-eat meals; coffee and tea; wine; cookies, chocolates and other sweets; other foods; and dietary supplements.

They gave participants scores ranging from a low of 0, for no organic food consumption, to 32 for the highest consumption.

In the group with the lowest organic food consumption, the average score was 0.72, compared to 19.4 in the group with the highest consumption.

Overall, by an average of 4.5 years after the surveys were completed, participants developed 1,340 new cancers. Most common were breast cancers, prostate cancers, skin cancers, colorectal cancers and lymphomas.

Along with its observational design, which can’t prove causality, another limitation of the study is that researchers didn’t account for why people who never ate organic might have made this decision.

They do know, however, that people who ate the most organic foods were more likely to be married, have higher income and education levels, consume less red and processed meat, and drink less alcohol.

“Asking about consumption of organic foods . . . assesses a behavior but not the causes of the behavior,” said Dr. Jorge Chavarro, coauthor of an accompanying editorial and a researcher at Harvard T.H. Chan School of Public Health and Brigham and Women’s Hospital in Boston.

“Someone who did not to eat organic because of price barriers was considered the same as someone who chose not to eat organic because they didn’t care about it,” Chavarro said by email. “While these two people may have the same level of biological exposure, they are different in terms of their motivation to eat organic and likely in many other aspects of their health behaviors, which could ultimately explain the observed differences in cancer risk in this study.”

SOURCE: bit.ly/2ANRMp2 JAMA Internal Medicine, online October 22, 2018.