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Fishing for a Healthy Heart?

Omega-3 fatty acids promote elasticity in blood vessels

FRIDAY, July 26, 2002 (HealthDayNews) -- You've probably heard that eating fish is good for your heart, but you may not know exactly why.

Now, researchers from Australia can tell you just how the omega-3 fatty acids found in ocean fish help keep your cardiovascular system running smoothly: They help keep your arteries more elastic.

That's important because "the arteries need to expand with each heartbeat to accommodate the output from the heart," says study author Dr. Paul Nestel, head of cardiovascular nutrition at the Baker Heart Research Institute in Melbourne. "With age and diseases such as diabetes, arteries become stiff and this process leads to hypertension and coronary heart disease."

"The two fish oil fatty acids were able to reverse this stiffness," he adds.

Cardiovascular disease affects more than 60 million Americans, and causes almost 100,000 deaths a year, according to the American Heart Association.

For their study, published in the August issue of the American Journal of Clinical Nutrition, Nestel and his colleagues recruited 38 middle-aged volunteers, both male and female, who had high levels of cholesterol.

Twelve of the study participants a daily supplement of eicosapentaenoic acid (EPA) for seven weeks; another 12 received supplements of docosahexaenoic acid (DHA); and the remaining 14 received a placebo pill every day during the study.

Both EPA and DHA are omega-3 fatty acids found in all fish, but salmon, mackerel, tuna, sardines, trout and herring have the highest concentrations of them, Nestel says.

The doses of the fatty acids given in the study were high -- three grams a day. According to Dr. William Wickermeyer, director of the lipid clinic at Iowa Heart Hospital in Des Moines, one gram daily is the average recommended dose.

The researchers found elasticity rose in the EPA group by 36 percent and by 27 percent in the DHA group, while there was no change in the placebo group. Blood pressure readings went down for the omega-3 groups, but the drop was not statistically significant.

"We know [from other studies] that these are beneficial substances," Wickermeyer says. "Now, we're backtracking to see why they're beneficial."

Wickermeyer says if you'd like to improve your heart health, aim for two servings of ocean fish a week.

If you don't like fish, he adds, it's fine to take omega-3 supplements.

But even fish isn't risk-free. On Thursday, an advisory panel to the Food and Drug Administration cautioned pregnant women against overindulging in tuna, which, though healthful, may contain mercury. Tuna is the most popular fish eaten in this country.

The FDA's Food Advisory Committee has just recommended that, until more information is known, pregnant women should eat no more than two 6-ounce cans a week to avoid passing on mercury to their babies. And if they eat other kinds of fish that are mercury-free, they should limit themselves to one can a week.

Last year, the FDA urged pregnant women to avoid four types of fish known to be high in mercury levels: shark, swordfish, king mackerel, and tilefish.

What To Do

This article from the American Medical Association looks at how omega-3 fatty acids lower heart disease. The Mayo Clinic offers these tips for eating a heart-healthy diet.

SOURCES: Paul Nestel, M.D., professor, medicine, and head, cardiovascular nutrition, Baker Heart Research Institute, Melbourne, Australia; William Wickermeyer, M.D., cardiologist, and director, lipid clinic, Iowa Heart Hospital, Des Moines, Iowa; Associated Press; August 2002 American Journal of Clinical Nutrition
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