Wednesday, September 5, 2012

Is organic food healthier than conventional?

The recent Stanford study has been duly making the rounds in the press. Despite the author's best intentions, there are now probably loads of folks running around telling each other that "organic isn't really healthier". Or wondering if it is worth the extra premium to buy organic. And to some degree, they are right!

Before we get all carried away, let's break this study down.

1) It is a meta-analysis review article, not a study with new findings. What they did was pull together about 237 previous studies, and attempt to synthesize findings. Of those, 17 involved actual human subjects being measured (for instance, for pesticide reside in urine). The other 220 studies were measuring various attributes of food, not its effects in humans. For instance, some of the studies looked at "bacterial contamination" whilst others assessed contents of vitamins and minerals.

2) The specific findings that stand out are these: a) "organic" food is not on average richer in vitamins and minerals than conventional counterparts, b) levels of microbial contamination are not necessarily lower in organic, c) organic foods lead to reduced pesticide exposure (which may even be under-estimated due to sampling methods).

What this just goes to show is that variation in farm management, and other on-farm and off-farm factors, override the significance of the "organic" label in determining the nutritional content of foods. I fully believe this to be true- and I thought so long before this particular headline. I've done Brix readings (a measure of sugars, amino acids, and other solutes in plant tissue-- thought to be a correlate of overall nutrient density, although this is a subject for a blog post in itself) on Cal-Organics salad mixes which scored so poorly as to be barely detectable. My refractometer was confirming my taste buds, that much of what is certified organic salad is really little better than water and cellulose nutritionally.

But here's the rub: reduced exposure to pesticides is still a great thing! We still know extremely little about how the long-term cumulative exposure to numerous different synthetic toxins affects vertebrates, particularly not for a human lifespan. The precautionary principle, and past track record of chemicals getting pulled from the market, suggests that we not risk it any more than is necessary.

Now, I don't have time to get into all the issues surrounding organic labeling. Let's just say it has pro's and con's. It is a provisionally useful label. Ideally, we'd like to know more about how a farm is run than whether it is certified organic-- other factors certainly are more important in predicting the healthfulness of the food that is produced. In fact, I personally take a nuanced approach to chemical fertilizers- I think they are sometimes useful, and not necessarily incompatible with sustainable soil management. The goal is a non-addictive use of fertilizing materials-- use them to secure abundant, healthy harvests, while still building organic matter long-term. Again, a future blog post in the works about practical soil fertility management and crop health and quality.

For now, don't buy into the headlines uncritically! This study is no justification for claiming that organic doesn't mean anything, and therefore isn't worth buying.


  1. Hey Chris! Nice blog. I agree wholeheartedly with your assessment. As one whose biological research is reductionist to the point of invisibility, the generalizations of studies like this are frustrating to hear about.

    I looked up the study and its table presenting nutritional meta-analysis. I'm not a statistic guy, but it seems to state that among studies comparing total phenol content, 3-to-1 of the comparisons favor organics. As you know, phenols are a broad class encompassing many beneficial molecules, and the biological activity of the majority of these phenols is unknown. Yet another reason to call the sensational headline of the study "premature."

    Anyway, looking forward to you piece on Methanogens, Been brushing up on their physiology myself recently, boy do those bugs use a lot of cobalamin.

  2. Hi Ted, thanks for stopping by! I am also interested in the secondary metabolites side- it ends up tying into my primary focus of grazing ecology quite strongly. I've seen some cool research coming out of Europe comparing organics to conventional on this. From a plant physiology perspective, it kind of makes sense to me. I also wonder about interactions between plant genotypes and soil management. A lot of conventional agronomy has been breeding for very low secondary contents.

    Even I thought the methane cycling stuff would be a lot simpler than it is! I have a few dozen citations I've collected, and I still feel like what we don't know eclipses what we do. Whenever I get something done I'll send it to you for a "friendly review" ;) Why do they need so much B12?


  3. Methanogens like cobalamin for its methyltransferase ability, and the cofactor makes up an essential part of assimilating C1 compounds into both carbon metabolism and energy generation (via methanogenesis). I think the latter reason is why archaea make so much of it, it's not usually so vital to central metabolism in the other domains of life. I'd be happy to take a non-expert look at your post when you're ready with it!