Organic Food, Health and the Burden of Proof

Under the halo effect of "natural and organic," Whole Foods shoppers may feel they can't go wrong nutritionally. I beg to differ.
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Paradoxically, my long-standing interest in organic food has encompassed both ardent support and concerned opposition.

My support for organic food -- and my own family's frequent selection of it -- has largely been based on potential benefits to the planet. These, I think are self evident, so I won't elaborate them here. My concern has been based on the misinterpretations of what organic means.

Organic does not mean "nutritious." Broccoli may be grown conventionally, but still has the nutritional profile of broccoli. Gummy bears -- and sugar, for that matter -- may be organic, which says something good about what they don't contain (pesticide residues). However, it says nothing good about what they do contain, or add to your diet.

Considerable mischief has come from supply-side misrepresentations of organic. Tapping into the burgeoning public interest in "going green," the food industry has draped products in labels touting organic ingredients even when such ingredients are a nominal part of the whole.

According to the USDA, any food sporting "organic" on its label must be "produced by farmers who emphasize the use of renewable resources and the conservation of soil and water to enhance environmental quality for future generations."

Further, "organic meat, poultry, eggs and dairy products come from animals that are given no antibiotics or growth hormones. Organic food is produced without using most conventional pesticides, fertilizers made with synthetic ingredients or sewage sludge [a comfort, to be sure], bioengineering or ionizing radiation."

There is, of course, the fine print. A label that says "organic" is noteworthy for not saying "100 percent organic." Ninety-five percent of the ingredients in such a product must be organic, but the rest can be ... whatever. In products "made with organic ingredients" up to 30 percent of the content need not be. We may get the truth on a food label, but rarely the whole truth.

The industry has done much to propagate the view that organic and nutritious are synonymous. The prevailing view, for example, seems to be that Whole Foods sells only nutritious foods, when, in fact, its commitment to selling "natural and organic" products guarantees no such thing. Standard offerings include, for instance, whipped cream and pepperoni pizza. In any other supermarket, shoppers would recognize these as dubious choices for health promotion -- but under the halo effect of "natural and organic," Whole Foods shoppers may feel they can't go wrong nutritionally. I beg to differ.

When developing the Overall Nutritional Quality Index that now powers the NuVal nutrition guidance system (, an international team of leading nutrition and public health experts and I wrestled with this dilemma. While we unanimously supported organic food philosophically, we were forced to conclude in 2007 that there simply wasn't sufficient science to include organic in an evidence-based measure of nutritional quality. Work on updating the NuVal algorithm will begin with the release of the 2010 Dietary Guidelines for Americans, and we will once again need to address this issue.

Ironically, both sides of the organic/health debate have received a boost from recent research. A study just published in Pediatrics found higher levels of pesticide metabolites in the urine of children with attention deficit disorder. The association between organochlorine pesticides, which affect the nervous system, and ADD makes sense, and was clear in this new study despite a good attempt to control for other factors. Pesticides residues may or may not "cause" ADD, but they are at least implicated by association. Other research over recent years suggests that organic produce may be, on average, 20 percent more concentrated in vitamins and minerals than conventionally grown produce.

On the other hand, a systematic review of the literature on organic foods published May 12 in the American Journal of Clinical Nutrition concluded that "evidence is lacking for nutrition-related health effects."

This paper, however, bespeaks absence of evidence, not evidence of absence. Consider what it would take to PROVE that organic foods confer a health benefit.

Imagine a clinical trial in which 1,000 people are assigned to strictly organic foods, and another 1,000 to conventionally grown foods, for 10 years. Such a trial would be enormously costly, cumbersome and logistically demanding -- if feasible at all. Some chemical contaminants would almost certainly get into the diets of the 'organic' group despite the very best efforts to prevent it, and these would also contaminate the study- because they would narrow the intended difference between treatment groups.

Nonetheless, imagine there were three fewer cases of cancer, and/or of ADHD, and/or perhaps several other maladies, in the organic group. Just "three fewer cases" over 10 years would be too few to distinguish from a statistical fluke in a sample of a thousand people. And, realistically, there might be even less than three fewer cases of cancer, because many cancers develop over a period of more than 10 years; a 10 year study might just not be long enough.

But let's imagine there were, indeed, three fewer cases of cancer, three fewer cases of ADHD, three fewer neurological ailments, and so on, in the organic group over a 10 year period. While none of this would likely be statistically distinguishable from random variation, consider what it would mean to the public health. Three extra cases of cancer per ten years in 1,000 people caused by pesticide residues would mean 3,000 extra cancers every ten years per million people! In a population of 300 million, it means 300,000 extra cancers every decade!

What this tells us is that the health effects of pesticide residues and other common contaminants of conventionally produced food could be truly enormous at the population level, and still all but invisible to epidemiologic research.

Organic and nutritious do not, and never will, mean the same thing -- please be aware of that, and beware marketing messages to the contrary. But along with known benefits of organic food for the planet, we have more and more hints of potential health benefits as well. The case gets incrementally stronger with time that a food that is nutritious to begin with is better still if organic.

While we don't have, and are unlikely to get, definitive proof of the health benefits of eating organic, perhaps it's time for the burden of proof to go the other way: since organic food is better for the planet and is likely to be better for health, we should accept it as such ... unless someone can prove it isn't!


Dr. David L. Katz;

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