An international study, due out this week in the British Journal of Nutrition, concludes that organic foods may have more antioxidants and less pesticides and toxic metals. But it doesn’t provide any proof that organic necessarily means healthier.
The study was based on of an analysis of 343 peer-reviewed studies from around the world that examined differences between organic and conventional fruit, veggies, and cereals. Lead researcher Carlo Leifert of Newcastle University told The Guardian that antioxidant levels were between 19 and 69 percent higher in organic food.
But Professor Richared Mithen of the Institute of Food Research thinks such statements are misleading. “The references to ‘antioxidants’ and ‘antioxidant activity,’ and various ‘antioxidant’ assays would suggest a poor knowledge of the current understanding within the nutrition community of how fruit and vegetables may maintain and improve health,” he explains.
The study also raises other concerns from within the food and nutrition community.
The research is certain to be criticised: the inclusion of so many studies in the analysis could mean poor quality work skews the results, although the team did ‘sensitivity analyses’ and found that excluding weaker work did not significantly change the outcome.
Also, the higher levels of cadmium and pesticides in conventional produce were still well below regulatory limits. But the researchers say cadmium accumulates over time in the body and that some people may wish to avoid this, and that pesticide limits are set individually, not for the cocktail of chemicals used on crops.
A further criticism is that the differences seen may result from different climate, soil types and crop varieties, and not from organic farming, though the researchers argue that combining many studies should average out these other differences.
The greatest criticism, however, will be over the suggestions of potential health benefits. The most recent major analysis, which took in 223 studies in 2012, found little evidence. “The published literature lacks strong evidence that organic foods are significantly more nutritious than conventional foods,” it found.
“You are not going to be better nourished if you eat organic food,” says Tom Sanders, professor of nutrition at Kings College London. “What is most important is what you eat, not whether it’s organic or conventional. It’s whether you eat fruit and vegetables at all. People are buying into a lifestyle system. They get an assurance it is not being grown with chemicals and is not grown by big business.”
But Sanders does point out that organic farming results in less fertilizer runoff and soil degradation.