Two common reasons for people choosing to buy organic foods include reduced use of pesticides and other chemicals and the belief that less greenhouse gases are generated by organic farming. In addition, many people think that organically grown foods have superior nutritional content.
A team from the London School of Hygiene identified 55 studies addressing the nutritional content of organic versus nonorganic foods that they deemed to be methodologically sound. A systematic review of the data showed that, among 11 different types of evaluated nutrient content, only 3 showed small but significant differences between organic and conventional foods. Conventionally produced crops had higher levels of nitrogen, and organically produced crops had higher levels of phosphorus and acidity. The authors judged the differences to have no clinical significance.
Some previous nonsystematic reviews have concluded that organically produced foods have superior nutrient composition; however, this large systematic review leads to a different conclusion. Hotly debated questions remain about whether the pesticides and chemicals that are used in producing conventional foods have clinical consequences. And, whereas most people agree that production of organic foods is “greener,” discussions continue as to how important the difference in farming methods is to the larger problem of global climate change.
Dangour AD, Dodhia SK, Hayter A, et al. Nutritional quality of organic foods: A systematic review. Am J Clin Nutr; Jul. 29, 2009; [e-pub ahead of print]. (http://dx.doi.org/10.3945/ajcn.2009.28041)
Anthony L. Komaroff, MD. Journal Watch General Medicine; Sept. 15, 2009; 29(18): 143