The popularity of organic products is skyrocketing in the United States. Between 1997 and 2011, U.S. sales of organic foods increased from $3.6 billion to $24.4 billion, and many consumers are willing to pay a premium for these products. Organic foods are generally grown without synthetic pesticides or fertilizers or routine use of antibiotics or growth hormones, and they are often twice as expensive as their conventionally grown counterparts. For instance, you’re in the supermarket eying a basket of sweet, juicy plums. You reach for the conventionally grown fruit, and then decide to pony up the extra $1/pound for its organic cousin. You figure you’ve just made the healthier decision by choosing the organic product. But have you? This is a common perception — perhaps based on this high price, or simply on one’s naturalistic fantasies—that organic foods are better for you than the conventional ones.
In order to provide some guidance, a recent extensive review of this subject was provided by a team from Stanford University[i]. They evaluated a large number of existing studies comparing organic and conventional foods.
In their study the researchers sifted through thousands of scientific publications and identified 237 of the most relevant to analyze. Those included 17 studies (six of which were randomized clinical trials) of populations consuming organic and conventional diets, and 223 studies that compared either the nutrient levels or the bacterial, fungal or pesticide contamination of various products (fruits, vegetables, grains, meats, milk, poultry, and eggs) grown organically and conventionally. There were no long-term studies of health outcomes of people consuming organic versus conventionally produced food; the duration of the studies involving human subjects ranged from two days to two years.
After analyzing the data, the researchers found little significant difference in health benefits between organic and conventional foods. No consistent differences were seen in the vitamin content of organic products, and only one nutrient — phosphorus — was significantly higher in organic versus conventionally grown produce (and the researchers noted that because few people have phosphorous deficiency, this had little health significance). There was also no difference in protein or fat content between organic and conventional milk, though evidence from a limited number of studies suggested that organic milk may contain higher levels of omega-3 fatty acids, a finding also of questionable benefit.
The review yielded scant evidence that conventional foods posed greater health risks than organic products. While researchers found that organic produce had a 30 percent lower risk of pesticide contamination than conventional fruits and vegetables, organic foods are not necessarily 100 percent free of pesticides. What’s more, as the researchers noted, the pesticide levels of all foods generally fell within the allowable safety limits. Two studies of children consuming organic and conventional diets did find lower levels of pesticide residues in the urine of children on organic diets, though the significance of these findings on child health was also unclear. Additionally, organic chicken and pork appeared to reduce exposure to antibiotic-resistant bacteria, but the clinical significance of this again is questionable.
So what can we conclude from all this? First, there is no real evidence that organic foods are more nutritious than conventional foods. If your taste buds are highly sensitive and you can discern a better flavor with organic foods (most people can’t), then go ahead and buy—provided you can afford it! On the other hand, there is no convincing proof that minor increases in pesticide or chemical residuals in conventional food are an actual threat to health, but long-term studies should help to provide more definitive information. In the meantime, you can minimize the risks of such contamination by simply washing off conventional foods prior to preparing and serving them at the table.
[i] Smith-Spangler CS, Brandeau MS, Hunter GE, et al.
Are Organic Foods Safer or Healthier Than Conventional Alternatives?
A Systematic Review. Ann Intern Med. 2012;157(5):348-66.