London, July 29 - Organic food has no nutritional or health benefits over conventionally produced food, according to a major study published on Wednesday.
Its conclusions were challenged by organic food campaigners.
Researchers from the London School of Hygiene & Tropical Medicine said consumers paid higher prices for organic food in part because of its perceived health benefits, creating a global organic market worth an estimated $48 billion in 2007.
A systematic review of 162 scientific papers published in the scientific literature over the last 50 years, however, found there was no significant difference.
"A small number of differences in nutrient content were found to exist between organically and conventionally produced foodstuffs, but these are unlikely to be of any public health relevance," said Alan Dangour, one of the report's authors.
"Our review indicates that there is currently no evidence to support the selection of organically over conventionally produced foods on the basis of nutritional superiority."
The results of research, which was commissioned by the British government's Food Standards Agency, were published in the American Journal of Clinical Nutrition.
Peter Melchett, policy director of Britain's Soil Association, which promotes organic farming, said he was disappointed by the conclusions reached by the study's authors.
He criticised the methodology of the study, which he said had led researchers to reject some clear nutritional benefits as "not important".
Melchett also pointed out there was not sufficient research to assess the long-term effects of pesticides on human health.
Sales of organic food have fallen in some markets, including Britain, as recession has led consumers to cut back on purchases.
The Soil Association said in April that growth in sales of organic products in Britain slowed to just 1.7 percent in 2008, well below the average annual growth rate of 26 percent over the last decade, following a plunge in demand at the end of the year.