The Waters Deepen in Debate Over Fish’s Health Benefits

Last month, three studies added to the evidence that omega-3 fatty acids, primarily found in fish, appeared to lower the risk of dying from a sudden heart attack--a reason the American Heart Assn. recommends eating fish twice a week.

Given that fish is low in saturated fat and a good source of protein, and that 250,000 Americans collapse and die from sudden heart attacks each year, it seems like a no-brainer that it should be a regular part of everyone’s diet. But as with many things in health, the issue is more complicated.

Last year, the Food and Drug Administration issued a warning that pregnant women, women who could become pregnant, nursing mothers, infants and toddlers should not eat shark, swordfish, king mackerel and tilefish because of the risk of exposure to mercury, which can affect brain development in fetuses and young children. The FDA said that these groups can eat about 12 ounces of other cooked fish a week--that’s about two servings a week.

But the Environmental Working Group, a research and advocacy group in Washington, D.C.--based on its analysis of mercury test results from seven government sources--recommended a wider ban on fish for women of childbearing age and very young children. It included not only the FDA’s list but also: tuna steak, sea bass, oysters from the Gulf Coast, marlin, halibut, pike walleye, white croaker and largemouth bass. It said these women and children should eat no more than one meal per month, if their fish of choice is canned tuna, mahi-mahi, blue mussel, Eastern oyster, cod, pollock, salmon from the Great Lakes, blue crab from the Gulf of Mexico, wild channel catfish and lake whitefish.

So, to eat fish or not to eat fish?

“I eat fish,” said Dr. Christine Albert of the division of preventive medicine at Brigham and Women’s Hospital in Boston.

That may be in part because Albert was lead author of a study of 278 men published April 11 in the New England Journal of Medicine that found men with the highest levels of omega-3 fatty acids in their blood had 81% less chance of dying from a sudden heart attack than men with the lowest levels.

Albert was also an author of a study published the day before in the Journal of the American Medical Assn.: In the ongoing Nurses Health Study of 84,688 women, those who ate the most fish had 44% less risk of dying from a heart attack than those who ate the least.

An Italian study that appeared the same week in the journal Circulation followed 11,323 men and women who had had a heart attack fewer than three months before. Over a year, one-third received usual care, one-third received 300 milligrams of vitamin E a day and one-third was given 1 gram of fish oil a day. After three months, those taking fish oil had a 41% lower risk of dying from a repeat heart attack compared to the usual care group. Although the mechanism is not understood, it appears that omega-3 fatty acids protect against uneven heart rhythms, according to Alice Lichtenstein, professor of nutrition science and policy at Tufts University in Boston.

These fatty acids are largely found in fish, especially fatty fish such as salmon, bluefish, mackerel and swordfish. There is also evidence that the fatty acids can lower blood triglyceride levels, help the immune system, play a role in clotting and maintaining good blood pressure and help develop a baby’s central nervous system.

But fish, especially large fatty fish, can absorb methylmercury, a highly toxic form that can cause learning delays, according to a National Academy of Sciences report issued in 2000. Dr. Philip Landrigan, chairman of the department of community and preventive medicine at Mount Sinai Hospital in Manhattan, recommends that women of childbearing years and young children “be selective about the species they eat.” Younger fish--such as canned tuna rather than large sushi-style tuna--may be a safer option, he said, because it has less time to accumulate mercury.

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Ridgely Ochs writes for Newsday, a Tribune company.