The Merriam-Webster dictionary defines superstition as:
…a belief or practice resulting from ignorance, fear of the unknown, trust in magic or chance, or a false conception of causation.
Using carefully selected studies, the organic food industry's lobbying organization, the Organic Consumers Association, makes claims like …
On average, organic is 25% more nutritious in terms of vitamins and minerals than products derived from industrial agriculture.
What can the hell can a phrase like 25 percent more nutritious mean? Never mind. A new comprehensive study, "Are Organic Foods Safer or Healthier Than Conventional Alternatives?," published by researchers at the Stanford University in the Annals of Internal Medicine (AIM) that looked at 240 different studies concludes that the answer is: No. As the New York Times reported:
They concluded that fruits and vegetables labeled organic were, on average, no more nutritious than their conventional counterparts, which tend to be far less expensive. Nor were they any less likely to be contaminated by dangerous bacteria like E. coli.
The researchers also found no obvious health advantages to organic meats.
Conventional fruits and vegetables did have more pesticide residue, but the levels were almost always under the allowed safety limits, the scientists said. The Environmental Protection Agency sets the limits at levels that it says do not harm humans.
"When we began this project, we thought that there would likely be some findings that would support the superiority of organics over conventional food," said Dr. Dena Bravata, a senior affiliate with Stanford's Center for Health Policy and the senior author of the paper, which appears in Tuesday's issue of the Annals of Internal Medicine. "I think we were definitely surprised."
Surprised? That's kind of like being surprised when a voodoo ceremony doesn't cure the sniffles or a skin rash. A 2009 comprehensive review of the data comparing the nutritrional value of organic versus conventional foods in the American Journal of Clinical Nutrition had earlier concluded:
On the basis of a systematic review of studies of satisfactory quality, there is no evidence of a difference in nutrient quality between organically and conventionally produced foodstuffs. The small differences in nutrient content detected are biologically plausible and mostly relate to differences in production methods.
So if organic foods aren't more nutritious than conventional foods, perhaps they offer other benefits? As the Times notes:
Dr. Bravata agreed that people bought organic food for a variety of reasons — concerns about the effects of pesticides on young children, the environmental impact of large-scale conventional farming and the potential public health threat if antibiotic-resistant bacterial genes jumped to human pathogens. "Those are perfectly valid," she said.
Regarding pesticides, the Stanford researchers found that 38 percent of conventional produce tested contained detectable residues, whereas 7 percent organic produce did. Does this matter? The Food and Drug Administration (FDA) monitors pesticide residues and its most recent report notes:
The pesticide residue levels found were well below regulatory standards. Results of baby foods tested in FY 2008 (and earlier years) also provide evidence of only low levels of pesticide residues in these foods.
The AIM study abstract noted:
Two studies reported significantly lower urinary pesticide levels among children consuming organic versus conventional diets, but studies of biomarker and nutrient levels in serum, urine, breast milk, and semen in adults did not identify clinically meaningful differences.
What about the alleged environmental advantages of organic farming? As I noted in my 2002 article, "Organic Alchemy," a 21-year Swiss study found some benefits from organic farming compared to conventional, including including greater water retention by the soil and a higher presence of beneficial insects. However, these benefits must be weighed against lower crop productivity. As I noted:
One of the most frequent criticisms of organic agriculture is that it is not as productive as conventional farming. The Swiss scientists confirmed this: Their organic plots were on average 20 percent less productive than conventional plots. For potatoes, organic production was about 40 percent lower. The researchers also point out that "cereal crop yields in Europe typically are 60 to 70% of those under conventional management." Furthermore, they dispelled the notion that organic crops are superior food by noting, "There were minor differences between the farming systems in food quality."
Catch that last sentence? Minor differences in food quality. And lower crop productivity means that more forests and grasslands must be plowed up to produce food.
What about differences in anti-biotic resistant bacteria? As the AIM study's abstract notes:
Escherichia coli contamination risk did not differ between organic and conventional produce. Bacterial contamination of retail chicken and pork was common but unrelated to farming method. However, the risk for isolating bacteria resistant to 3 or more antibiotics was higher in conventional than in organic chicken and pork (risk difference, 33% [CI, 21% to 45%]).
Conventional farmers often dose their meat animals with antibiotics as a way to boost their growth by preventing infections. This does speed the development of microbes resistant to the antibiotics used, and the concern is that such resistant microbes will infect people or exchange resistance genes with human disease microbes. Earlier this year, the FDA began the process of limiting the use of antibiotics as animal growth enhancers. However, the New York Times noted that…
…organic meat contained considerably lower levels of antibiotic-resistant bacteria than conventionally raised animals did, but bacteria, antibiotic-resistant or otherwise, would be killed during cooking.
With regard to differences in the presence of microbes on conventional versus organic produce, a 2005 study of washed and unwashed spring mix salad greens reported:
The mean populations of mesophilic and psychrotrophic bacteria, yeasts, molds, lactic acid bacteria, and coliforms on conventionally grown spring mix were not statistically different (P > 0.05) from respective mean populations on organically grown spring mix. The mean population of each microbial group was significantly higher on unwashed spring mix compared with the washed product.
In other words, if you believe in the germ theory of disease, wash your vegetables. In any case, the Times is probably right when it observes:
The findings seem unlikely to sway many fans of organic food.
The question that organic proponents should ask themselves is: Is there any scientific evidence that would persuade you that you are wrong? If not, then you should just admit it's a superstitious preference and stop disparaging (lying about?) the safety and nutrition of cheaper conventional foods.