Two recent Harvard studies support the American Heart Association's advice to make fish a regular part of a heart-healthy diet. As reported in the Journal of the American Medical Association and the New England Journal of Medicine, several weekly servings of fish - a prime source of omega-3 fatty acids - seem to help protect both men and women from heart disease.

Large studies support the link

Looking at data collected on participants of the ongoing Physicians' Health Study, researchers compared blood levels of omega-3 fatty acids of 94 men who died suddenly of a heart attack with those of 184 men of the same age. They found that men with the highest blood levels of omega-3 fatty acids were more than 80% less likely than those with the lowest levels to die of a heart attack.

Another analysis was done over a 16-year period on more than 84,000 participants of the Nurses' Health Study. In this case, women who ate fish at least once a week were about 30% less likely than those who rarely ate fish to have heart disease or to die from a heart attack.

How it may work

Scientists think that omega-3 fatty acids help protect heart cells from ventricular tachycardia - a rapid, erratic heartbeat that can result in cardiac arrest. Omega-3s may also inhibit the development of heart disease by lowering elevated blood triglyceride levels and by making the blood platelets less likely to clump together, reducing the risk that an errant blood clot will block an artery and lead to a heart attack or stroke.

Where to get your omega-3s

Omega-3 fatty acids cannot be manufactured in the body, so you have to get them from your diet. Cold-water fish like salmon, tuna, mackerel, and herring are particularly good sources of omega-3s, but most varieties of fish contain some. In addition, flaxseed, canola and soybean oils, as well as some nuts and seeds, contain a fatty acid that can be converted by the body into a usable form of omega-3s.

What about supplements?

Fish oil supplements may seem to some to be an attractive alternative to eating fish, but it's not clear if taking supplements, without making any dietary changes, would have a protective effect on heart health. Note that the participants of the Nurses' Health Study who ate the most fish also tended to eat more chicken and produce, and less red meat, than women who rarely ate fish, meaning that their diets were more healthful for reasons other than just the omega-3 fatty acids from fish.

If you're not a fan of fish, consider using canola or soybean oil and margarine made from these oils in place of other vegetable fats, or try sprinkling ground flaxseeds on salads, hot or cold cereal, or yogurt and fruit. Both options can boost your intake of omega-3 fatty acids and make your diet more heart-healthy.

If you're considering fish oil supplements, talk to your physician first. These supplements can deliver doses of omega-3s much higher than would normally be found in foods. And because omega-3s can make the blood less likely to clot, high doses could do more harm than good.