Preventive medicine: Does the consumption of biological products prevent cancer?

For years, I wrote – more recently in a dedicated entry in The Truth About Foods – that despite my general enthusiasm for organic foods and the environmental benefits of organic farming, direct evidence of the benefits for human health organic foods are very rare and sufficient. elusive. This is still the case this week, but with a remarkable additive. A study recently published in JAMA Internal Medicine associates current consumption of organic foods with a reduced cancer risk.

French researchers have followed nearly 70,000 people for 10 years, which gives the study a great statistical power. They evaluated the frequency of consumption of various foods available in organic and conventional versions, creating a 32-point scale. They found significantly lower overall cancer rates – a relative reduction of 25% on average – among those with the highest rates compared to those with the lowest frequency of organic food consumption.

This new study, however, was not a randomized trial. It is rather an observational cohort study called NutriNet-Health. Study participants share online information on a wide range of habits and lifestyles, as well as on health outcomes. Researchers analyze associations.

Association studies can not prove the cause and effect for a reason as obvious as the schoolyard's split: two things can be "true, true, but without any connection". Those who consume organic foods consciously and most often can simply systematically differ from those more cavalier about it. Perhaps they are more cautious about everything, more devoted to health, more attentive.

NutriNet-Santé researchers have done an excellent job in capturing many other variables that can "explain" the association between organic foods and cancer risk. They collected data on the habits and quality of food, smoking, exercise, environmental exposures, education, and so on. But this diligent effort does not completely eliminate the possibility that the consumption of biological products and less cancer is nevertheless "true, true and unrelated," a concession that researchers make clear and with humility.

Of course, a study on a subject of such great interest has generated many reactions in the media, inevitably hyperbolic in both directions. Some titles have made the leap in favor of cause and effect, offering organic foods as a recognized opportunity to reduce the risk of cancer. Detractors quickly jumped and noted that since the new study did not prove the same, no such thing was true.

I do not really care about hyperbole in one way or the other, but I have a particular problem with the total rejection of this research by some. First of all, let's be clear: some of the interests of the food industry would simply prefer that the many chemical alterations in our food supply not be found guilty of crimes they may well commit. If the denunciations of the new study come from such sources, we can not trust them.

On the other hand, search methods are systematically criticized by entities that do not like the results – but who use exactly the same methods as gospel when these same entities like the results. All parties in the "regime wars" use this tactic and I renounce it in any case. The strengths and limitations of the given methods are what they are, regardless of the results and regardless of whether we like them or not.

For yet another, there is insinuation that, because a simple association study does not prove the cause and effect, the cause-and-effect relationships have therefore been … refuted. This, of course, is total nonsense. As the French authors correctly point out, their study suggests an association that deserves to be deepened. But in the meantime, their study suggests association. The group of people who consumed organic products more often had less cancer. This desirable result is attributable to something. The impossibility of reaching the threshold of definitive proof is not the same as that of not providing support. The new study supports the plausible and optimistic proposition that consuming organic products could reduce the risk of cancer over the course of life.

No, the new study does not prove that consuming organic products will reduce your risk of cancer. But in the context of meaning as well as science, it gives hope. As there are many other good reasons to promote organic foods, I encourage you to do so whenever you can reasonably.

Dr. David L. Katz Author, The Truth About Food.