Organic milk may contain more short-chain omega-3 fatty acids than conventional milk, but this does not translate into clear nutritional benefits for consumers, said Deirdre Hutton, chair of the UK Food Standards Agency (FSA), in a letter to the scientists.
A three-year study conducted at the Universities of Glasgow and Liverpool found organic milk contained 68 per cent more omega-3 fatty acids on average than conventional milk. Scientists involved asked the FSA in August to recognise the nutritional difference between organic and conventional milk.
Omega-3s are considered to cut consumers' risk of heart disease, and have been linked with better concentration in children.
But, the FSA has repeatedly refused to recognise that any organic food products are healthier or carried significant nutritional differences from their conventional counterparts.
Hutton, in her letter, said there was no evidence to support the scientists' claims that the a-linoleic acid (ALA) found in the organic milk was an important source of long-chain omega-3 fatty acids. It is long-chain omega-3 acids, like those found in oily fish, that are considered to carry the health benefits.
Studies have shown that short-chain omega-3 varieties, like ALA, can convert themselves into long-chain omega-3s, but Hutton said a recent review had found this process was limited.
"Organic milk consumed in volumes that would be consistent with a healthy balanced diet would therefore not provide sufficient amounts of [long-chain fatty acids] to provide cardiovascular or foetal developmental benefits associated with these nutrients."
Her comments are a blow to organic milk producers, who may have looked to tap into the large amount of publicity linking omega-3 and health in the UK.
Organic milk sales have boomed in Britain over the last few years and were 50 per cent higher this July than in the same month last year, according to new figures from the Milk Development Council.
The Organic Milk Suppliers' Co-operative (OMSCo), which sponsored the recent study in Glasgow and Liverpool, sells organic milk that it claims is higher in omega-3 as well as vitamins E and A, than non-organic rivals. The milk is sold under the Altogether Better brand.
OMSCo was reportedly pleased that the FSA had recognised some nutritional difference between organic and conventional milk. But the group said it had not asked the FSA to comment on the relative health qualities of organic and conventional milk.