Organic vs. conventional food on health: not enough data

Written by Colby Vorland

This post was chosen as an Editor's Selection for ResearchBlogging.orgYou may recall last year’s review by Dangour and colleagues that concluded, based on 162 studies, that “there is no evidence of a difference in nutrient quality between organically and conventionally produced foodstuffs.”
This brought about much controversy on the web, as well as a rebuttal by Benbrook et al.  Media reporting that failed to acknowledge limitations of this research, such as that it did not examine potential contaminant use, health outcomes, or environmental effects further confused the public.
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.


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

Written by Guest Expert

Colby Vorland is a PhD student in nutritional science at Purdue University. He is studying the regulation of intestinal phosphorus absorption in health and chronic kidney disease. Colby has a background in dietetics and has previously worked in lipid metabolism in non-alcoholic fatty liver disease.


  1. An interesting facet of ‘the debate’ regards howls of indignation from those who claim there have been ‘no long-term feeding studies’ of GM crops.
    Now the organic industry, certainly the most shrill of all opponents of GM crops, has to account for the lack of anything conclusive from 52 years testing anything they’d like to devise.
    One popular definition of insanity is doing something over and over and expecting a different result. Saying there’s “not enough data yet” about organic food production merely restates the problem.
    52 years is long enough to discover that organic food production is a political movement without any discernible advantage in terms of human nutrition, and to move on.

  2. Human nutrition is not the only thing that Organic is about. But it is interesting to note that claims of greater healthfulness are prolific in organic agriculture, without much research to back it up. When one recent big report about organic and nutritional content came out and found little difference, even Marion Nestle listed the reasons why she buys it, which doesn’t include the belief that it is more nutritious. One important thing to remember is that conventional farms are not barred from using organic techniques, while there are restrictions on organic farms. So even if a certain management practice in organic was found to enhance nutritional aspects of crops, that could be applied to conventional ag easily. The issue in my mind is how do we create a reliable market for nutritionally enhanced foods that is not over-hyped, reliable, and affordable?

  3. One problem in applying useful organic methods to conventional farming is that, in my experience, organic farmers and researchers that study organic farming methods are not interested in studying which specific methods are causing improvements. The scientific method generally requires us to hold all things equal while testing one aspect but that isn’t an accepted paradigm with organic practitioners, in my experience*. This means that advances in organic farming don’t ever get to the mainstream, which is, frankly, stupid. As I said in Toward a better agriculture for everyone, only 6% of US farmland is organic, so what happens in organic doesn’t really do much if it stays in organic fields. What we need to do is find the methods that work and move them to conventional farms as quickly as possible.
    *I’m sure that some are willing to do this but I haven’t met any or read any papers that indicate otherwise. If you know of some, please let me know!

  4. Yes the perspective is that Organic is “holistic” while conventional is “reductionistic.” However, whenever comparing Organic with Conventional, as people in both farming systems like to do, you are essentially being reductionistic. Differences in outcome are being “reduced” to differences between the two agricultural systems. It is that desire not to peek into the details and tease out the variables that bothers me. There could be practices within the system that are “riders” like amendments added to a congressional bill that dilute (or kill) the bill. For instance, I heard from Raoul Adamchak that companion planting was found not to help.

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