Organic vs. conventional food on health: not enough data

You may recall last year’s review by Dangour and colleagues that concluded, based on 162 studies (55 met the inclusion criteria), that “there is no evidence of a differencein nutrient quality between organically and conventionally producedfoodstuffs.”

This brought about much controversy on the web, as well as a rebuttal by Benbrook et al.  Media reporting complained about this research, such as that it did not examine potential contaminant use, health outcomes, or environmental effects further confused the public (it wasn’t meant to!).

In short, this is still a controversial area, and it is clear that there are many methodological issues with most existing studies that make conclusions difficult to reach at this point.

Hopefully the group is prepared for round 2 of media distortion, as they just published a new paper (1), this time they examined how organic and conventionally grown food differentially effect health.

From the last 52 years of research, only 12 studies met their inclusion criteria (even with a low quality threshold), which needed health outcomes, direct comparisons for organic vs. conventional foods, among others.  Among the 12 studies, 8 were human in vivo, 3 human in vitro, and 1 animal study.  8 of the 12 hypothesized that a higher nutrient content in organic food would result in different health effects, and the other 4 studied differences on markers of carcinogenesis, and carotenoid and polyphenol bioavailabilities.

10 of the studies had a primary outcome of a change in antioxidant activity, which is a biomarker but does not necessarily mean anything for health outcomes.  The other 2 studies recorded proxy-reported measures of atopic manifestations and breast milk fatty acid composition with implied health benefits to infants.

So really, this review doesn’t tell us much because the studies are as the authors put it, “very heterogeneous in terms of designs and quality, study population or cell line, exposures tested, and health outcomes measured.”

There is simply not enough data yet.

Reference

1. Dangour AD, Lock K, Hayter A, Aikenhead A, Allen E, & Uauy R (2010). Nutrition-related health effects of organic foods: a systematic review. The American journal of clinical nutrition PMID: 20463045