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Original Investigation
October 22, 2018

Association of Frequency of Organic Food Consumption With Cancer RiskFindings From the NutriNet-Santé Prospective Cohort Study

Author Affiliations
  • 1Centre de Recherche Epidémiologie et Statistique Sorbonne Paris Cité, Institut National de la Santé et de la Recherche Médicale (INSERM) U1153, Institut National de la Recherche Agronomique (INRA) U1125, Conservatoire National des Arts et Métiers, Université Paris 13, Equipe de Recherche en Epidémiologie Nutritionnelle, Bobigny, France
  • 2Département de Dermatologie, Hôpital St André, Bordeaux, France
  • 3Département de Santé Publique, Hôpital Avicenne, Bobigny, France
  • 4Centre de Recherche en Cardiovasculaire et Nutrition, Aix Marseille Université, INSERM, INRA, Marseille, France
JAMA Intern Med. Published online October 22, 2018. doi:10.1001/jamainternmed.2018.4357
Key Points

Question  What is the association between an organic food–based diet (ie, a diet less likely to contain pesticide residues) and cancer risk?

Findings  In a population-based cohort study of 68 946 French adults, a significant reduction in the risk of cancer was observed among high consumers of organic food.

Meaning  A higher frequency of organic food consumption was associated with a reduced risk of cancer; if the findings are confirmed, promoting organic food consumption in the general population could be a promising preventive strategy against cancer.

Abstract

Importance  Although organic foods are less likely to contain pesticide residues than conventional foods, few studies have examined the association of organic food consumption with cancer risk.

Objective  To prospectively investigate the association between organic food consumption and the risk of cancer in a large cohort of French adults.

Design, Setting, and Participants  In this population-based prospective cohort study among French adult volunteers, data were included from participants with available information on organic food consumption frequency and dietary intake. For 16 products, participants reported their consumption frequency of labeled organic foods (never, occasionally, or most of the time). An organic food score was then computed (range, 0-32 points). The follow-up dates were May 10, 2009, to November 30, 2016.

Main Outcomes and Measures  This study estimated the risk of cancer in association with the organic food score (modeled as quartiles) using Cox proportional hazards regression models adjusted for potential cancer risk factors.

Results  Among 68 946 participants (78.0% female; mean [SD] age at baseline, 44.2 [14.5] years), 1340 first incident cancer cases were identified during follow-up, with the most prevalent being 459 breast cancers, 180 prostate cancers, 135 skin cancers, 99 colorectal cancers, 47 non-Hodgkin lymphomas, and 15 other lymphomas. High organic food scores were inversely associated with the overall risk of cancer (hazard ratio for quartile 4 vs quartile 1, 0.75; 95% CI, 0.63-0.88; P for trend = .001; absolute risk reduction, 0.6%; hazard ratio for a 5-point increase, 0.92; 95% CI, 0.88-0.96).

Conclusions and Relevance  A higher frequency of organic food consumption was associated with a reduced risk of cancer. Although the study findings need to be confirmed, promoting organic food consumption in the general population could be a promising preventive strategy against cancer.

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    3 Comments for this article
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    Strange design
    Jean-Francois Grenier, MD |
    Please, correct me if i'm wrong, but this study has a very strange and weak design.
    The dietary profile of participants was assessed only once ("Two months after enrollment, volunteers were asked to provide information on their consumption frequency of 16 labeled organic products").
    Moreover, while the authors state that they used a somewhat validated questionnaire, in their commentary Drs. Hemler, Chavarro and Hu, write:
    "Most salient among the weaknesses is the fact that the organic food questionnaire was not validated; therefore, it is unclear what the intended exposure, organic food consumption, was actually measuring."
    So, how could anyone
    draw any conclusions based on a single assessment made with an unvalidated questionnaire?
    CONFLICT OF INTEREST: None Reported
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    Interesting, but a few questions remain.
    Sebastien Causse |
    The findings are very interesting, but the significance of the differences appears rather light. The factosr may well be causally unrelated to consumption of organic food, yet correlated, and this could be enough to send the differences of incidence under the significance threshold.
    In that regard, in supplemental table 7, we can see that other variables change between the quartiles. For example milk, legume and poultry consumption. However, the models did not adjust for these. Red and processed meat were adjusted for, I assume because higher cancer risk was associated with these food categories, however one should not assume that
    because it has not been described, milk, poultry or legumes might not have an effect of their own, and the model should have been adjusted for that.
    Otherwise, suggesting that pesticides are the cause of the cancers is somewhat risky.

    An extra analysis of interest would be to see if there are specific food groups where organic vs conventional sourcing has a higher impact on the incidence of the reported cancers. According to the methods paragraph, the authors should have this kind of data. Does a PCA or MFA suggest any link? This would be particularly interesting as it could indirectly point towards a more specific subgroup of pesticides (organic eggs or milk are not exposed to the same pesticides as cereals or legumes), and perhaps support the authors' claim of pesticide involvement.
    This could also reduce the risk of an unidentified confounding factor (see first comment): if the incidence of cancers can be related to the consumption of organic food in a specific food group instead of the general consumption of organic food, then it is less likely that causality is due to difference of lifestyle (that is, if we assume that other healthy lifestyle habits correlate to organic food consumption on the whole and not the consumption of organic food of a specific group).
    CONFLICT OF INTEREST: None Reported
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    Ethics
    Naomi Boldon, Ethics | Rocky Vista University
    Julia Baudry, et al used a French research study to make associations between health and nutrition, backing up their claim that eating organic foods lowers the risks for developing cancer. The study referenced in the article included 68,946 patients, 78% women with a mean age at baseline of 44.2 years. According to the article, women are more prone than men to develop cancer. This helps to solidify the authors’ claims but does not take into account other age groups—particularly those more vulnerable like children or the elderly. While the study was well conducted, additional research is needed to clarify all aspects of the authors’ claims.
    As physicians it is our responsibility to make recommendations as well as to educate our patients about diet and lifestyle. In doing so, we are incorporating beneficence into our daily practice. Education regarding diet not only helps to improve the lives of our patients, but by extension also has the potential to improve the nutrition of the patient’s families and communities as they in turn educate others around them about what they have learned from us.
    There are an increasing number of regions within the United States that are beginning to ban GMO foods (https://gmo.geneticliteracyproject.org/FAQ/where-are-gmos-grown-and-banned). These bans may include the banning of cultivation and/or imports or limit specific crops to GMO cultivation. Some examples of regions participating in the GMO bans include Boulder County, Colorado, as well as cities throughout California and Maine. In addition to comments made in the article about considering the different classes of pesticides used, I am referencing GMO foods in this context because the pesticide Roundup is applied to 80% of these conventionally grown foods (http://www.isaaa.org/resources/publications/briefs/44/download/isaaa-brief-44-2012.pdf). States such as California have recently moved for labeling of glyphosate (the main ingredient in Roundup) as a known human carcinogen (https://www.sfgate.com/news/article/State-can-label-widely-used-herbicide-as-possible-12849147.php). This alone should alert us as to the importance of being conscious about where our food comes from, how it is grown and harvested, and what effects these can have on our overall health and vitality.
    The article also mentions that, “natural pesticides allowed in organic farming in the European Union exhibit much lower toxic effects than the synthetic pesticides used in conventional farming.” While there are multitudes of factors that go into the growth and progression of cancer, world reports do show that there are fewer instances of cancer in European countries than in the United States (https://www.theguardian.com/news/datablog/2011/jan/24/worldwide-cancer-rates-uk-rate-drops). This leads me to ask what the toxic effects of natural pesticides might include or what regulations are considered safe for organic farming practices. These points were not addressed in the article but would be important for  follow up. A more in-depth approach to the topic would further educate not only physicians but also our patients and their families and communities.
    CONFLICT OF INTEREST: None Reported
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