The benefits of eating fish outweigh any potential health risks from pollutants, a study has concluded.
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The Harvard School of Public Health reviewed existing studies that looked at the health effects of eating fish. They concluded eating up to two portions of fish a week was beneficial, and eating fish could cut the risk of death from heart disease by a third.
Experts said the Journal of the American Medical Association findings backed UK recommendations. The evidence across different studies showed that fish consumption lowers the risk of death from heart disease by 36%.
The reduced rated of heart disease comes, researchers say, from eating about three ounces of farmed salmon or six ounces of mackerel each week. The benefit was related to the level of intake of omega-3 fatty acids, and thus benefits are greater for oily fish such as salmon, which are higher in such acids, than lean fish, such as haddock and cod.
The researchers also suggest eating that amount of fish or fish oil intake reduces total mortality by 17%.
Dariush Mozaffarian, lead author of the study said: "Overall, for major health outcomes among adults, the benefits of eating fish greatly outweigh the risks. "Somehow this evidence has been lost on the public."
Concerns have been raised about chemicals found in fish from pollution. These include mercury, polychlorinated biphenyls (PCBs) and dioxins. Mr Mozaffarian added: "The levels of PCBs and dioxins in fish species are low, similar to other commonly consumed foods such as beef, chicken, pork, eggs, and butter.
"Importantly, the possible health risks of these low levels of PCBs and dioxins in fish are only a small fraction of the much better established health benefits of the omega-3 fatty acids."
The researchers conducted a search of publications to evaluate studies that looked at the relationship between fish intake and major health benefits, as well as the health risks from pollutants.
Researchers also say they found omega-3 fatty acids from seafood were likely to improve early brain development for infants and young children, and that these benefits can be obtained for babies from pregnant or nursing mothers who consumed fish.
Researcher Eric Rimm said: "Unfortunately, the media and others may have contributed to this confusion by greatly exaggerating the unsubstantiated claim of a health risk from fish.
"These results, from over two decades of research, clearly show there is a health risk if adults don't eat fish."
Judy More, a dietician from the British Dietetic Association, said the research reinforces the advice given by the Food Standards Agency. "The advice in the UK is to eat two servings of fish a week and make one of them oily," she said.
"This research backs that up, which is a good thing because the UK population doesn't eat enough fish. "But the biggest problem with fish testing is that the figures vary. You will get different levels of pollution in different parts of the Atlantic. "The figures provided here are mainly from North America, so whether we would see a difference in Europe we don't know."
The researchers say they did not find definite evidence that low-level mercury exposure from seafood consumption had harmful effects on health in adults. They did, however, find that mercury may lessen the cardiovascular benefit - but not cause overall harm - from eating some fish.
The research paper appears in the October issue of The Journal of the American Medical Association.