Fish oil and your heart

Interest in the heart-health benefits of fish oil dates back about two decades, beginning with a 1980 study showing that Eskimos in Greenland — who eat nearly a pound of fish a day — have low rates of death from heart disease. In subsequent years, there has been substantial research on the effects of fish oil on the heart and arteries. Laboratory studies have shown that fish oil, which contains what are known as n-3 or omega-3 fatty acids, makes blood platelets less sticky, helps protect the linings of arteries, and may also lower blood pressure.

Population studies from several countries have shown lower rates of heart disease in people who eat fish regularly. In 1998, data from the Physicians’ Health Study showed that eating fish once a week versus less than once monthly halved the likelihood of dying suddenly from a heart attack. Total heart attack rates were not affected by fish consumption or the amount of omega-3 fatty acids ingested. One year later, a report in Lancet described a randomized trial in which men who’d had a heart attack received either a fish oil supplement, 300 mg of vitamin E, both, or neither. The groups who received the fish oil supplement had significantly lower rates of heart attack, stroke, and death during the next three and a half years. Rates of sudden death dropped by 45%.

Additional support for fish oils comes from a report on nearly 80,000 women in the Nurses’ Health Study. Published in 2001 in the Journal of the American Medical Association, this 14-year study found that eating fish at least twice a week versus less than once a month cut in half the risk of strokes caused by clots blocking an artery to the brain. The Nurses’ Health Study also found that eating one to three servings of fish per month cut the risk of heart disease by 20%, while eating at least five servings a week lowered risk by 40%.

Anyone hoping to benefit from fish oil would probably be better off sticking with dietary sources, primarily from cold-water fish such as salmon, trout, mackerel, sardines, and herring. Forgoing meat for cold-water fish, or any fish for that matter, may lower cholesterol and heart disease risk simply by reducing the amount of saturated fat in your diet.

Three groups of people may benefit from fish oil supplements. One group includes people with arrhythmias, or disordered heart rhythms. The omega-3 fatty acids in fish oil can stabilize wayward electrical activity in the heart and calm arrhythmias. The second group includes people with high levels of triglycerides, especially those who can’t control the problem through diet and exercise, because fish oil supplements have been shown to help lower triglycerides. The third group includes people with coronary heart disease. The American Heart Association recommends that these people eat one serving of fatty fish a day; recognizing that this may be more fish than most people will eat, the association notes that a supplement can be substituted.