A review of research into the nutritional benefits of organic foods compared to conventional has shown that organic “confers no significant health benefit”, reports The New York Times, The Times the BBC and others. But organic advocates say that the researcher’s “medicalised” approach to the subject drowned out real differences between organic and conventional.
The meta-analysis, carried out by scientists at Stanford University in the US, examined 17 studies comparing people who ate organic with those who did not and 223 studies that compared the levels of nutrients, bacteria, fungus or pesticides in various foods – including fruits, vegetables, grains, meats, milk and eggs.
The scientists found that fruit and vegetables contained similar amounts of vitamins, and milk the same amount of protein and fat – although some studies showed organic milk contained more healthy omega-3 fats. They concluded that organic fruit and vegetables were no more nutritious than their conventional counterparts. The researchers also found no obvious health advantages to organic meats.
However the review did show that a third of conventional produce contained detectable pesticide residues, compared to seven percent of organic produce samples. And organic meat was 33 percent less likely to carry bacteria resistant to three or more antibiotics than conventionally-produced meat.
Lead researcher, Dr Dena Bravata, said that for consumers making a choice between organic and conventional food on the basis of nutrient levels “there is not robust evidence to choose one or the other”.
But Chensheng Lu, who studies environmental health and exposure at the Harvard School of Public Health in Boston, said that while “the jury is still out” on nutritional differences, people should consider pesticide exposure in their grocery-shopping decisions.
“If I was a smart consumer, I would choose food that has no pesticides,” Lu, told Reuters Health. “I think that’s the best way to protect your health.” He said that more research was needed to fully explore the potential health and safety differences between organic and conventional foods, adding that it’s “premature” to make conclusions either way.
US organic advocates said that the Stanford team had failed to appreciate differences they did find between organic and conventional – such as pesticide residues and antibiotic resistant bacteria. “Those are the big motivators for the organic consumer,” commented Christine Bushway, executive director of the Organic Trade Association.
The Soil Association, which says the Stanford survey “has limited value in Europe”, agreed. A spokesperson criticized the approach taken by the researchers. “Studies that treat crop trials as if they were clinical trials of medicines, like this one, exaggerate the variation between studies, and drown out the real differences.
“A UK review paper, using the correct statistical analysis, has found that most of the differences in nutrient levels between organic and non-organic fruit and vegetables seen in this US study are actually highly significant.”