Academics specialising in phytochemicals say they are "not at all surprised" the European Food Safety Authority (EFSA) has rejected generic health claims about antioxidants.
Derek Stewart, a scientist at the Scottish Crop Research Institute, said: "I'm not at all surprised. The term antioxidants has become so bastardised it's meaningless.
"Anything can be an antioxidant in a test tube, but that doesn't tell you anything about how it will behave in the body. Lots of firms have also got into this game comparing ORAC levels (oxygen radical absorbence capacity) of things containing completely different sets of compounds, such as apples and bananas. It pulls the wool over people's eyes.
"This doesn't mean they don't have health benefits, though. The problem for the food industry is that short-term human intervention studies which EFSA is focusing on won't deliver dramatic results for something like antioxidants. That would require studies lasting years, which are prohibitively expensive."
Alan Crozier, professor of plant biochemistry and human nutrition at the University of Glasgow, said bioavailability was key. "More research is needed to establish which flavonoids, phenolic compounds and related metabolites actually gain access to appropriate cells in the body to exert biological effects."
By mopping up free radicals (destructive byproducts of respiration), antioxidants have been claimed to assist healthy ageing. But despite compelling epidemiological evidence linking higher fruit consumption with lower incidence of chronic disease, the results of human intervention trials with antioxidant supplements were mixed, he said.