“It’s not what you don’t know that hurts you,
it’s what you know that isn’t so.”
— attributed variously to Mark Twain and to Will Rogers

Many popular ideas are popular not because they’re right but because of a widespread failure of skepticism. For example, in the 1970s the idea that wide lapels really make you look great was widely adopted without rigorous testing.

Organic food has grown to a $26 billion industry in the last couple of decades largely on public good will. This industry was perfectly poised at the intersection of several of our irrational biases – our fear of “chemicals”, our assumption that natural is better than artificial, and our suspicion of technology that alters living things. Surely our food must be healthier without all those industrial “chemicals”, we told ourselves as we spent sometimes twice as much for organic produce.

My regular readers know that I’ve written previously (links below) that there is no proof whatsoever that organic food is healthier than conventional food. In the current issue of the Annals of Internal Medicine, the question is finally given some rigorous examination.

Since the adjective “organic” is sometimes bandied about carelessly, we should have a general consensus about what it means. Organic plants are grown without synthetic pesticides or fertilizers and are not genetically modified. Organic livestock is raised without growth hormones or routine (i.e. preventive) antibiotics. Organic livestock is fed organically produced feed and is provided access to the outdoors and freedom of movement. Organic food is also generally manufactured without additives or irradiation.

The authors of the paper retrieved every peer-reviewed study that compared either organically and conventionally grown food or the people eating these foods. 240 of these studies were found and their findings were reviewed. The results were strikingly blah, prompting a flurry of media coverage (links below).

The studies found no difference in health outcomes between people eating organic and conventional food. Two studies found higher pesticide levels in the urine of children eating conventional food compared to organic food, but these levels were well below those that cause health problems. There were also no consistent meaningful differences in nutrient levels between the two groups.

I have long been suspicious that organic produce has higher risks for bacterial contamination since the alternative to synthetic fertilizer is fertilizer from animal waste. This also turns out to be unfounded. Bacterial contamination of food was similar in both groups.

There was one small but tantalizing difference. Bacterial contamination of meat was similar in frequency in both farming methods, but bacterial contamination with bacteria resistant to three or more antibiotics was significantly more common in traditionally grown chicken and pork than organically grown animals. That doesn’t prove that the humans who eat that meat are more likely to get sick or that their illnesses would be harder to treat, but it suggests that routine use of antibiotics in livestock has risks which require further study.

There may be lots of other good reasons to buy and eat organic food. Some people think organic food tastes better, and of course that is best left to each one’s palate. Others assert that organic farming practices are better for the environment. But organic farming consumes more resources and uses much more land per food produced, so if most of us ate organic food much more of the environment would be taken up for farming than is currently. There are also ethical reasons to refrain from supporting farming practices that treat animals cruelly. I’m not suggesting that we should not eat organic food, only that we should not do it with the expectation that it is healthier.

So for now, I’ll take my apple with pesticides. Oh, and those lapels are still groovy, no matter what other people say.

Learn more:
Are Organic Foods Safer or Healthier Than Conventional Alternatives?: A Systematic Review (Annals of Internal Medicine)
Why Organic Food May Not Be Healthier For You (NPR Morning Edition)
Study Questions How Much Better Organic Food Is (Associated Press)
Organic food no more nutritious than non-organic, study finds (NBC News)

My previous posts about organic food:

When the Stool Hits the Sprouts
Would You Like Some Salmonella With That?

For a very informative description of the benefits of modern farming, as well as other technical revolutions that make modern life possible, I highly recommend “The Rational Optimist: How Prosperity Evolves” by Matt Ridley.

Tangential Miscellany

Dr. Kevin Pho, the very well known physician blogger and outspoken advocate of social media in medicine, published my post about the coming flood of newly-insured patients. If you didn’t read it when I posted it three weeks ago, you might want to take a look. Check out the comments, too. Many of them are, shall we say, vigorously opposed to my point of view.