Many studies have shown the nutritional benefits o

 Many studies have shown the nutritional benefits of eating fish (finfish or shellfish). Fish is high in protein and omega-3 fatty acids. But concerns have been raised in recent years about chemicals found in fish from environmental pollution, including mercury, PCBs and dioxins. That has led to confusion among the public--do the risks of eating fish outweigh the benefits?

Researchers from the Harvard School of Public Health (HSPH) tackled that question by undertaking the single most comprehensive analysis to date of fish and health. In the first review to combine the evidence for major health effects of omega-3 fatty acids, major health risks of mercury, and major health risks of PCBs and dioxins in both adults and infants/young children, the results show that the benefits of eating a modest amount of fish per week--about 3 ounces of farmed salmon or 6 ounces of mackerel--reduced the risk of death from coronary heart disease (CHD) by 36%. Notably, by combining results of randomized clinical trials, the investigators also demonstrated that intake of fish or fish oil reduces total mortality--deaths from any causes--by 17%.

Included with the paper, which appears in the October 18, 2006, issue of The Journal of the American Medical Association, is the first comprehensive summary of levels of omega-3 fatty acids, mercury, PCBs and dioxins in various species of fish and other foods, including chicken, beef, pork, butter and eggs.

"Overall, for major health outcomes among adults, the benefits of eating fish greatly outweigh the risks," said Dariush Mozaffarian, lead author of the study and an instructor in epidemiology at HSPH and in medicine at Brigham and Women's Hospital. "Somehow this evidence has been lost on the public."

More than two decades ago, pioneering studies showed that Greenland Eskimos, who consumed high amounts of omega-3 fatty acids from seafood, had very low rates of CHD death. Further studies found that omega-3