An analysis of 24 studies based on randomiased clinical trials, has found that the fish oil supplements lacked efficacy across a range of health outcomes for which their use was advocated.
The Washington Post reported that the supplements were bought anyway and US citizens spent roughly $1.2 billion each year on fish oil pills and associated products.
One of the authors of that JAMA research had told Reuters in 2013, about 10 per cent of Americans took them for their touted content of the beneficial omega-3 fatty acids.
However, while they were generally considered safe to take, it was not clear whether they were beneficial for heart health.
The report said that the National Institutes of Health and American Heart Association could not really make up their minds.
While the former endorsed the supplements, it also added "omega-3s in supplement form have not been shown to protect against heart disease" on its website.
However, commentators say it was possible there was some health benefit, which the experiments on heart disease patients just could not pick up as heart medications clouded things.
A 5-year study of 26,000 people, which The New York Times termed "more representative of the general population" would be completed in 2016.
''I think that the era of fish oil as medication could be considered over now,'' said Dr Gianni Tognoni of the Institute for Pharmacological Research in Milan, the New York Times reported.
According to commentators, it would be interesting to see how much these kinds of studies affected the way people took supplements.