Eat more fish for a healthy heart

ASK AN expert to list the ways that fish is good for your heart, and it  may take a while. But ask for advice, and you’ll get a quick answer: Eat fish once or twice a week and you’ll see cardiovascular benefits. Fish are nature’s richest source of long-chain omega-3 fatty acids, nutrients that have been firmly tied to a wide range of cardiovascular health benefits. They cut overall heart-disease risk, reduce the likelihood of sudden cardiac death, lower blood pressure, bring down levels of triglycerides and cholesterol, slow the progression of atherosclerosis or hardening of the arteries, and help shield us from developing potentially deadly abnormal heart rhythms. And that’s not all.

Omega-3 also appear to help the cells lining our blood vessels to function more effectively and to improve the tone of the autonomic nervous system, which is responsible for controlling the heart, says Dr Dariush Mozaffarian, an instructor of medicine at Harvard Medical School who has been researching fish and cardiovascular health for several years. In fact, the American Heart Association now recommends that everyone eat two six-ounce meals of fatty fish each week, and urges additional omega-3 intake via supplements for individuals at greater risk.

The fish richest in omega-3s are dark-fleshed varieties like salmon, sardines, mackerel and bluefish, while tuna is also a relatively good source. But even fish with lower levels of omega-3s remains high in protein and low in saturated fat, so it’s always a good menu choice — especially if it bumps a burger off your plate, says Dr Alice Lichtenstein of the Friedman School of Nutrition Science and Policy at Tufts University in Boston. But pregnant and nursing women, as well as women who are planning to become pregnant, should be careful about mercury when eating seafood. High  levels of this heavy metal in the body can lead to brain and nerve damage.

The US Food and Drug Administration advises pregnant and nursing women  to stay away from shark, tilefish, king mackerel and swordfish, but says pregnant women can eat up to 12 ounces of a variety of other fish each week. Polychlorinated biphenyls (PCBs), pollutants that can impair neurological development, are another common seafood contaminant. In guidelines issued last year, Physicians for Social Responsibility and the Association for Reproductive Health Professionals advised young women and children to eat no more than one or two servings each month of salmon, sardines, herring or bluefish in order to reduce PCB exposure. The groups echoed the FDA’s warning list on fish high in mercury, but added that marlin and grouper should only be eaten once weekly.

For most people, the benefits of omega-3s found in fish outweigh the risks posed by contaminants, Melissa Ohlson, a nutritionist in preventive cardiology at the Cleveland Clinic in Cleveland, Ohio, said. She advises people to mix it up, eating several different types of seafood in order to prevent high exposure to any single contaminant. There is one type of fish meal that won’t do your heart or blood vessels good. A study by Mozaffarian and his colleagues published in January found people 65 and older who ate fish sandwiches or fried fish more than once a week had a 44 per cent higher risk of stroke than those who indulged less frequently.

Consumption of fried fish or fish sandwiches also showed no relationship to levels of omega-3 fatty acids in the blood, although levels did increase with the amount of tuna or broiled or baked fish consumed, says Mozaffarian. Another study by Mozaffarian and his team, published in 2003, found eating baked or broiled fish at least once a week reduced the risk of developing an abnormal heart rhythm known as atrial fibrillation by 30 percent, while consumption of fried fish or fish sandwiches had no effect.

Fast-food restaurants likely use relatively lean, white fish, Mozaffarian notes, and tend to fry it in artery-clogging hydrogenated vegetable oils. Even worse, he added, some restaurants may use oil over and over again and allow it to burn, which produces additional harmful byproducts. But Mozaffarian and Lichtenstein agree that if you feel like frying up a filet at home you’ll be fine, as long as you use unsaturated fat like canola or soybean oil to prepare it. Baking, broiling and steaming are also excellent options. And the classic tuna sandwich — “on whole wheat, light on the mayo,” Lichtenstein advises — is always a good choice too.