A recent review of 240 studies has concluded that:
The published literature lacks strong evidence that organic foods are significantly more nutritious than conventional foods. Consumption of organic foods may reduce exposure to pesticide residues and antibiotic-resistant bacteria.
Organic produce has become increasingly popular in recent years. There are several reasons that consumers might prefer organic produce, including the belief that organic farming is better for the environment and more sustainable. I am going to focus in this article about the health effects of organic produce. Environmental claims for organic farming are complex and controversial – I will just say that such claims largely fall prey to the naturalistic and false dichotomy fallacies. In my opinion, farming practices should be evaluated on their own merits individually, based on evidence rather than philosophy. Sustainable and environmentally friendly farming are certainly laudable goals and I support farming practices promote them, however they are labeled.
The alleged superiority of organically grown produce is a separate question. In a 2003 survey 68.9% of people who purchase organic food said they did so because they believed it to be healthier (more than any other reason given). However, fifty years of research has so far not produced convincing evidence that there is any health benefit to consuming organic food. Likewise, systematic reviews of nutritional quality of organic produce also reveals no difference from conventional produce.
In 1952 Martin Gardner, who just passed away this week at the age of 95, wrote about organic farming in his book Fads and Fallacies in the Name of Science. He characterized it as a food fad without scientific justification. Now, 58 years later, the science has not changed much at all.
A recent review of the literature of the last 50 years shows that there is no evidence for health benefits from eating an organic diet. The only exception to this was evidence for a lower risk of eczema in children eating organic dairy products. But with so many potential correlations to look for, this can just be noise in the data.
Another important conclusion of this systematic review is the paucity of good research into organic food – they identified only 12 relevant trials. So while there is a lack of evidence for health benefits from eating an organic diet, we do not have enough high-quality studies to say this question has been definitively answered. It is surprising, given the fact that organic food was controversial in the 1950s, that so little good research has been done over the last half-century.
Diet advice changes so fast it’s almost a full-time job to keep up with it. Avoid cholesterol; no, avoid saturated fats; no, avoid trans-fats. Avocados are bad; no, avocados are good. Wheat germ is passé; now omega 3s are de rigueur. The supermarket overwhelms us with an embarras de richesses, a confusing superabundance of choices from “organic” to low-sodium. How can we decide what to have for dinner?
Michael Pollan, the author of The Omnivore’s Dilemma, has written a new book: In Defense of Food: An Eater’s Manifesto. He argues for a simplification of diet advice. He hones it down to seven words: Eat food. Not too much. Mostly plants. (more…)