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Organic produce certainly costs more than conventionally grown food, but is it better for you?

Evidence so far has suggested that there are no health benefits from eating organic food instead of conventionally grown produce. Now a review of the scientific literature concludes that organic consumers may be getting their money’s worth; it claims that organic food is more nutritious than conventionally grown fodder.

Researchers led by Carlo Leifert, who studies ecological agriculture at Newcastle University, UK, found that organic food contains significantly higher levels of “nutritionally desirable” antioxidants compared to conventional crops. For example, phenolic acids, flavanones and flavonols were 19%, 69% and 50% higher, respectively, in organic produce than in its conventional counterparts, says the study, which was published today in the British Journal of Nutrition.

The researchers also found that organic produce contains lower amounts of pesticide and lower concentrations of cadmium, a metal that can build up in the body through repeated exposure and become toxic. “There are significant composition differences between organic and conventional crops for a range of nutritionally relevant compounds,” they write.

The study finds that eating organic food could boost a person’s antioxidant intake by up to 40% — the equivalent of two portions of fruits or vegetables a day. This could provide “meaningful” benefits to human nutrition, the authors write, because many antioxidants have been linked to a lower risk of chronic diseases, including certain cancers. Still, Leifert told Nature that his team has “no evidence of what the potential health impact may be”.

Leifert says that the study is an improvement on earlier analyses because it includes a larger data set — 343 peer-reviewed studies — making its results more robust.

A 2009 review on behalf of the UK Food Standards Agency (FSA) in London looked at total of 67 studies on the nutritional content and health effects of organic and conventional produce. This study found no clear nutritional benefits of organic produce over conventionally grown food. Likewise, a review of 237 studies published the Annals of Internal Medicine in 2012 also found no significant differences.

Alan Dangour, a food and nutrition scientist at the London School of Hygiene and Tropical Medicine and lead author of the FSA review, told Nature that the latest study suffers from significant problems with its methods and analysis. It shows “no important differences in nutrient content between organically and conventionally produced food”, he says, adding that the paper includes many studies of varying quality, which affects the reliability of its results.

Leifert says that Dangour was “too selective” in the quality of research he chose to include in the FSA study and consequently omitted important information. He says that his team conducted an additional analysis on a more selective group of studies but found that their results and conclusions still largely confirmed nutritional differences between organic and conventional produce.

Other researchers also criticized the paper. Richard Mithen, a food and health researcher at the Institute of Food Research in Norwich, UK, said in a statement that there is no evidence that the small differences that the researchers found in the levels of antioxidants would have any consequences for public health. And Tom Sanders, a nutritional scientist at King’s College London, says that nothing in the study changes his view that there are no meaningful nutritional differences between conventional produce and organic crops.