Organic food is no healthier than ordinary food, a large independent review has concluded.
There is little difference in nutritional value and no evidence of any extra health benefits from eating organic produce, UK researchers found.
The Food Standards Agency, which commissioned the report, said the findings would help people make an "informed choice".
But the Soil Association criticised the study and called for better research.
Researchers from the London School of Hygiene and Tropical Medicine looked at all the evidence on nutrition and health benefits from the past 50 years.
Without large-scale, longitudinal research it is difficult to come to far-reaching clear conclusions on this, which was acknowledged by the authors of the FSA review
Peter Melchett, Soil Association
Among the 55 of 162 studies that were included in the final analysis, there were a small number of differences in nutrition between organic and conventionally produced food but not large enough to be of any public health relevance, said study leader Dr Alan Dangour.
Overall the report, which is published in the American Journal of Clinical Nutrition, found no differences in most nutrients in organically or conventionally grown crops, including in vitamin C, calcium, and iron.
The same was true for studies looking at meat, dairy and eggs.
Differences that were detected, for example in levels of nitrogen and phosphorus, were most likely to be due to differences in fertilizer use and ripeness at harvest and are unlikely to provide any health benefit, the report concluded.
The review did not look at pesticides or the environmental impact of different farming practices.
Gill Fine, FSA director of consumer choice and dietary health, said: "Ensuring people have accurate information is absolutely essential in allowing us all to make informed choices about the food we eat.
"This study does not mean that people should not eat organic food.
"What it shows is that there is little, if any, nutritional difference between organic and conventionally produced food and that there is no evidence of additional health benefits from eating organic food."
She added that the FSA was neither pro- nor anti-organic food and recognised there were many reasons why people choose to eat organic, including animal welfare or environmental concerns.
Organic food is just another scam to grab more money from us
Dr Dangour, said: "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."
He added that better quality studies were needed.
Peter Melchett, policy director at the Soil Association said they were disappointed with the conclusions.
"The review rejected almost all of the existing studies of comparisons between organic and non-organic nutritional differences.
"Although the researchers say that the differences between organic and non-organic food are not 'important', due to the relatively few studies, they report in their analysis that there are higher levels of beneficial nutrients in organic compared to non-organic foods.
"Without large-scale, longitudinal research it is difficult to come to far-reaching clear conclusions on this, which was acknowledged by the authors of the FSA review.
"Also, there is not sufficient research on the long-term effects of pesticides on human health," he added.
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