Review of studies involving 40,000 people points up benefits
WEDNESDAY, Aug. 5 (HealthDay News) -- A new review shows that the omega-3 fatty acids found in certain fish not only prevent cardiovascular disease, but may even help treat it.
"A lot of people know that omega-3 fatty acids are a good thing, but have thought of them in the area of nutritional or health foods," said study author Dr. Carl J. Lavie, medical director of cardiac rehabilitation and prevention at the Ochsner Clinic in New Orleans. "They don't realize there is so much data, a lot of data from big studies, that they are not only preventive but also help in therapy for a number of conditions, such as atrial fibrillation, heart attack, atherosclerosis and heart failure."
The report in the Aug. 11 issue of the Journal of the American College of Cardiology cites four trials with almost 40,000 participants that show benefits of omega-3 fatty acids in primary prevention of cardiovascular disease, in treatment after heart attack and, most recently, in heart failure patients.
The benefits of omega-3 fatty acids are such an old story that such studies can go unnoticed, Lavie said. "If you polled cardiologists about whether this is a good thing or a bad thing, I don't know if they would recognize how much has been done in this area," he noted.
As far back as 2002, the American Heart Association issued a scientific statement endorsing omega-3 fatty acid intake, from fish or supplements. It recommended specific amounts of omega-3 fatty acids each day for people in general, with greater intake recommended for people with heart disease.
"For the general population, it should be 500 milligrams a day," Lavie said. "If you have heart disease, it should be 800 or 1,000 milligrams a day."
Lavie includes himself in the second category, because "I have a family history of heart disease. I eat a lot of fish and take a supplement just to be sure."
It's got to be the right kind of fish, the oily species that have a lot of omega-3 fatty acids, Lavie added. "Redfish, trout, salmon," he said. "Salmon is my favorite."
Not much effort is needed for most people to achieve the recommended intake, Lavie said. "Five hundred milligrams a day is two fatty fish meals per week," he added.
But too many people eat non-oily fish such as catfish, Lavie noted. "And they have it fried, which reduces its health benefits," he added.
His review did turn up a few negative studies, including one showing no benefits of omega-3 fatty acids in people who had heart attacks. But it was a relatively small (4,000 people), short (one-year) trial, and the patients in the trial were already getting intensive drug therapy including clot-busting clopidogrel, cholesterol-lowering statins, beta blockers and ACE inhibitors, Lavie noted.
Set against that one trial are the many larger studies cited by Lavie, and epidemiological evidence showing that populations such as Asians and Alaskan Eskimos, whose diets are rich in fish oil, have a low incidence of cardiovascular disease.
The picture is not complete, the new report noted. Studies still must be done to determine the relative benefits of DHA and EPA, the long-chain fatty acids in the omega-3 family. And the American Heart Association says that Omega-3 supplements should be taken only after consulting with a doctor, because too much can cause excessive bleeding in some people.
Another study now in the recruiting stage will test omega-3 fatty acids to prevent not only cardiovascular disease but also cancer, said Dr. JoAnn Manson, chief of preventive medicine at the Harvard-affiliated Brigham and Women's Hospital.
She is a leader of the trial, which is now recruiting 10,000 men aged 60 and older and 10,000 women aged 65 and older. The researchers will test not only the effect of omega-3 fatty acids but also of vitamin D.
Both are "very promising nutrients in prevention of cardiovascular disease, cancer and other chronic diseases," Manson said. In the five-year trial, a quarter of the participants will take both vitamin D and omega-3 fatty acids, a quarter will take the vitamin, a quarter will take the fatty acids and a quarter will take a placebo.
Enthusiasts shouldn't anticipate the results of the trial and start taking large doses of omega-3 fatty acids, Manson warned. "It's too early to jump on the bandwagon and take megadoses, but moderate doses seem reasonable," she said.
Get the official view of the value of omega-3 fatty acids from the American Heart Association.
SOURCES: Carl J. Lavie, M.D., medical director, cardiac rehabilitation and prevention, Ochsner Clinic, New Orleans; JoAnn Manson, M.D., chief, preventive medicine, Brigham and Women's Hospital, Boston; Aug. 11, 2009, Journal of the American College of Cardiology
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