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Original Investigation
December 2018

Association of Frequency of Organic Food Consumption With Cancer Risk: Findings 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. 2018;178(12):1597-1606. 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, research investigating the underlying factors involved with this association is needed to implement adapted and targeted public health measures for cancer prevention.


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. If these findings are confirmed, further research is necessary to determine the underlying factors involved in this association.

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    5 Comments for this article
    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?
    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).
    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.
    Questions about the adjustments
    Long-Gang Zhao |
    The adjustments in the model are strange.
    In the main analyses, the author provided three models. The first model included age and sex. The second included other potential risk factors including dietary factors. The third included other specific foods and dietary pattern. The inclusion of specific foods is hard to explain as the goal of the study was to determine the effect of organic foods. The reason is that fiber, fruit and vegetable intake may be part of the organic foods. The inclusion of these food items may lead to over-adjustments.
    The Researchers Missed the Common Ingredient
    Douglas Costello |
    In looking at the various categories of food products included in the diets there is a common ingredient that has been ignored and that has a significant impact upon the biome.

    Preservatives are included in literally every product except possibly red meat and even then unless banned sodium nitrate solution is sprayed to maintain and enhance its redness. Commercial flours have preservatives added by the miller. Take a sliced loaf of bread a typical loaf and see how long it takes for mould to grow.

    If red meat caused cancer and particularly colorectal cancer we should
    have been experiencing elevated cancer instances but we haven't until the last thirty-five to forty years. Bacon gets its red colour from the use of sodium nitrate and sausages unless specifically made preservative free will all have a preservative added.

    So while diet will have an impact on the composition of the biome the preservatives contained in all food products until preservative free will actively work to destroy the biome setting the scene for colorectal cancer. Pesticides while an issue and potentially a cause are in this instance not the primary motivator. Eating organic foods is possibly the ideal but budgetary issues for many preclude that source. So while organic vegetables etc may be consumed any baked products either purchased cooked or made by the consumer unless from organic flour will have a preservative within it.

    Preservatives provide long shelf lives, and permit indifferent food handling in the home if food are left unrefrigerated for periods before and after cooking and before consumption.