SHOPPERS who are willing to pay more than three times the price of factory-farmed chicken for organic birds get no more benefit to their health, according to a study commissioned by the Food Standards Agency.
The agency said organic food did nothing to improve health or offer any more nutritional benefits than non-organic food.
The agency insisted that it was neither for nor against organic food. It stopped short of saying that buying organic was a waste of money. It said that there were no important benefits for health and that it was more important for people to eat a healthy, balanced diet.
The research, the biggest and most comprehensive of its kind, looked at research published on the health and nutritional benefits of organic produce over the past 50 years.
The researchers, from the London School of Hygiene and Tropical Medicine, were led by a public health nutritionist, Dr Alan Dangour.
They found that there was no significant benefit from drinking milk or eating meat, vegetables, fruit, poultry and eggs from organic sources, as opposed to the products of conventional farm systems.
Pro-organic groups criticised the findings of the year-long review, which cost pounds 120,000. They said that the conclusions, published in the American Journal of Clinical Nutrition, failed to take into account the impact of pesticides and herbicides. Organic farming bans artificial chemical fertilisers and has stricter animal welfare rules than conventional farming.
Dr Dangour said that, as a nutritionist, he was not qualified to look at pesticides. "There is a possibility that organic food has less pesticide residues, but this was not part of the review," he said. "Potentially this may be an area for further research."
He added: "A small number of differences in nutrient content were found to exist between organically and conventionally produced crops and livestock, but these are unlikely to be of any public health relevance.
"Our review indicates that there is currently no evidence to support the selection of organically over conventionally produced crops and livestock on the basis of nutritional supremacy." Among the differences identified by the study was a higher phosphorous content in organic food.
Dr Dangour said: "Phosphorous is an important mineral and is available in everything we eat. It is important for public health but the difference in the content between organic and conventional foods was not statistically relevant in terms of health."
He added: "Acidity is also higher in organic produce but acidity is about taste and sensory perception and makes no difference at all for health."
Nitrogen levels were found to be higher in conventional produce, but this was not surprising given the use of nitrogen as a fertiliser in commercial agriculture. But the levels posed no better or worse impacts on human health, the research said.
A study of 52,000 papers was made, but only 162 scientific papers published between January 1958 and February last year were deemed relevant, of which just 55 met the strict quality criteria for the study, Dr Dangour said.
Twenty-three nutrients were analysed. In 20 categories there were no significant differences between production methods and the nutrient content. The differences detected were most likely to have been due to differences in fertiliser use and ripeness at harvest, and were unlikely to provide any health benefits.
The Soil Association challenged the conclusions that some nutritional differences between organic and conventional food were not important. It said it was particularly concerned that the researchers dismissed higher levels of beneficial nutrients in organic food - such as 53.6 higher levels of beta-carotene and 38.4 per cent more flavonoids in organic foods - according to the mean percentage difference of samples analysed.
Dr Dangour was adamant that these were not relevant because of the level of standard error in the research - which was 37 per cent for beta-carotene and 10.6 per cent for flavonoids.
The authors said in their conclusion: "No evidence of a difference in content of nutrients and other substances between organically and conventionally produced crops and livestock products was detected for the majority of nutrient assessed in this review, suggesting that organically and conventionally produced crops and livestock products are broadly comparable in their nutrient content."