A new study has found that by dramatically reducing the risk of lymphomas and decreasing the risk of postmenopausal breast cancer, a diet that consists primarily of organic foods can lower an individual's overall risk of cancer.
Cancer development has been linked to pesticide exposure, and strict regulations mean that organic foods have a much lower occurrence of pesticide residues than conventionally produced foods do. However, research concerning whether organic foods actually reduce cancer risk has been extremely limited.
When a team of French researchers led by Julia Baudry, PhD, an epidemiologist at the Centre de Recherche Epidémiologie et Statistique Sorbonne Paris Cité, investigated data on 68,946 participants in the NutriNet-Santé study—a predominantly female (78%) cohort with a mean age of 44 at baseline, followed for an average of 5 years—they revealed that individuals consuming the highest proportion of organic food had a 25% reduced likelihood of having developed any cancer by the time of follow-up compared with those whose diet was least organic. This overall decrease in cancer risk resulted from a 76% lower lymphoma risk, including an 86% lower risk of non-Hodgkin lymphomas, and a 34% lower risk of postmenopausal breast cancer.
The researchers found that frequent organic food consumption was associated with a high-quality diet rich in fiber, vegetable proteins, and micronutrients, with increased consumption of fruits, vegetables, legumes, and nuts. It was also associated with reduced consumption of processed meat, poultry, other meat, and milk.
Accounting for these dietary factors did not modify the findings, however. High frequency of organic consumption reduced cancer risk in those with low- or medium-quality diets, and the association between cancer risk and a high-quality diet combined with frequent organic food consumption approached statistical significance. In their study, published in JAMA Internal Medicine, the authors hypothesize that "higher intake of pesticide-contaminated products may partly counterbalance the beneficial role of high-quality foods among individuals with a high dietary quality."
High levels of organic food consumption were also associated with a variety of non-dietary factors, including female gender, high occupational status or household monthly income, post-secondary education, physical activity, and status as a former smoker. The authors note the economics at play: "While organic food… may be important to reduce the risk of specific cancers, the high price of such foods remains an important hurdle."
In a commentary accompanying the published study, Elena Hemler and Jorge Chavarro, MD, ScD, of the Harvard T.H. Chan School of Public Health and Frank Hu, MD, PhD, of Brigham & Women's Hospital and Harvard Medical School raise the concern that the study authors did not validate the organic food questionnaire: "It is unclear what the intended exposure, organic food consumption, was actually measuring. Organic food intake is notoriously difficult to assess, and its self-report is highly susceptible to confounding by positive health behaviors and socioeconomic factors." Nevertheless, they say, the topic is an important one: "More research in this area is urgently needed because cancer is a serious public health challenge and foods containing pesticide residues are widely consumed. If future studies provide more solid evidence supporting the consumption of organic foods for cancer prevention, measures to lower costs and ensure equitable access to organic products will be crucial."
Ms. Hemler, Dr. Chavarro, and Dr. Hu also point out the importance of other health-related dietary factors: "Current recommendations should continue to focus on modifiable risk factors that are backed by solid evidence and encourage healthy dietary patterns, including higher intake of fruits and vegetables, whether conventional or organic."
For More Information
Baudry J, Assmann KE, Touvier M, et al (2018). Association of frequency of organic food consumption with cancer risk: findings from the NutriNet-Santé prospective cohort study. JAMA Intern Med. [Epub ahead of print] DOI:10.1001/jamainternmed.2018.4357Hemler EC, Chavarro JE & Hu FB (2018). Organic foods for cancer prevention—worth the investment? JAMA Intern Med. [Epub ahead of print] DOI:10.1001/jamainternmed.2018.4363