Of Organic Foods and Meta Analyses
There has been much bruiting in the conventional media and the blogosphere,
By Richard Romano
Published: September 21, 2012
Two hundred thirty-seven studies met inclusion criteria: 17 evaluated health outcomes among human populations consuming organic and conventional foods (54 –70); 223 compared organic and conventional fruits, vegetables, grains, meats, poultry, milk, or eggs directly (50 –53, 57, 65, 69, 71–286) (3 reported on both human and food outcomes).So really on 7% of the studies they analyzed directly looked at people consuming organic vs. conventional food. That’s a pretty scanty base upon which to be making overarching claims about health. And as for those 17 studies:
Seventeen articles describing 14 unique populations (13 806 participants) met inclusion criteria (Supplement 3, available at www.annals.org). Study designs varied: 6 randomized, controlled trials (56, 57, 62, 65, 66, 69), 2 prospective cohort studies (54, 61), 3 cross-sectional studies (55, 64, 68), 4 crossover studies (describing 2 populations) (59, 60, 63, 67), and 1 case– control study (70). Only 3 studies (61, 64, 70) examined clinical outcomes (for example, wheezing, allergic symptoms, or reported Campylobacter infections), and the remaining studies examined health markers (for example, serum lipid or vitamin levels).So even among those relevant studies there was a great deal of heterogeneity. In a nutshell, in order to answer the basic question, “is organic food healthier than conventional foods?” you would need to conduct a long-term study that followed one group of subjects who ate exclusively organic and another group that ate exclusively conventional, and then report their health outcomes after some period of time. Such studies may actually be underway somewhere, I don’t know, but at present the kinds of data required to make conclusive statements about organic food and human health is simply not available. Now, my intent is not to debunk the study (for what it is—a meta-analysis—it’s quite good at synthesizing what research has been done in this area, although some statistical legerdemain may have crept in), nor to rise up in defense of organic food (as I said, I am fairly blasé on the subject, quite frankly), but rather to point out that sometimes studies can be misrepresented in the media—and sometimes by a study’s own authors. The paper’s conclusion says 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.And this is true: in terms of basic nutrition, there is scant evidence that organic foods contain significantly greater amounts of nutrients than conventional foods. But human health is not just about nutrient quantity and/or quality. Avoiding pesticide residues may be a good thing as far as human health is concerned, as might avoiding antibiotic-resistant bacteria. So if we define health in that way, perhaps organic is better than conventional. I have nothing against the organic food movement, and if you want to support organic food as a political gesture, or as being environmentally beneficial, or even that it tastes better, great. But we need to be careful that we don’t ascribe benefits to something when the evidence is still too slim to conclusively demonstrate.