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Fish Oil Fizzles for Fighting Heart Attack, Stroke

By Salynn Boyles
WebMD Health News

Reviewed by Louise Chang, MD

Sept. 11, 2012 -- Millions of people take omega-3 supplements to improve their heart health, but new evidence questions their benefit.

Researchers looked at 20 studies involving nearly 70,000 people, many of whom were heart patients. Adding omega-3 to their diet did not appear to lower the chance of having a heart attack or stroke or lower the risk of death from these and other causes.

Many people take fish oil capsules to get omega-3. But, as in this study, not all omega-3 came from fish oil. It also came from other sources.

The study appears in the Sept. 12 issue of the Journal of the American Medical Association.

A study published last spring failed to show a benefit for omega-3 supplements in people with existing heart disease.

Omega-3 Didn't Appear to Lower Risk

The American Heart Association recommends that all adults eat at least two 3.5-ounce servings of fish a week, and that people with heart disease take about 1 gram total of two types of omega-3 fatty acids (EPA and DHA) per day, preferably from fatty fish.

Capsules containing DHA and EPA are an option, but talk to your doctor before using them.

The AHA also recommends that people with high levels of blood fats known as triglycerides take 2 to 4 grams of EPA+DHA per day under a doctor's care.

Higher doses should only be taken under the supervision of a doctor, as they can cause dangerous bleeding.

In the new analysis, when people who took omega-3 were compared to people who took placebo capsules, no major difference was seen in the risk for heart attacks, strokes, sudden cardiac death, and death between the two groups.

The findings do not justify the use of omega-3 supplements regularly as a treatment or prevention, researcher Evangelos C. Rizos, MD, and colleagues from Greece's University Hospital of Ioannina write in the Journal of the American Medical Association.

Analysis Findings 'Disheartening'

Heart doctor David A. Friedman, MD, calls the new analysis, pun intended, "disheartening."

He is the chief of heart failure services for North Shore-LIJ Plainview Hospital in Plainview, N.Y.

Friedman prescribes high-dose omega-3 to many of his patients, and he says the supplements clearly lower blood triglyceride levels.

But he says this may not translate into the heart benefits that had been expected.

"It may be that food sources of omega-3, rather than supplements, are a better choice," he says.

Fish Oil and Heart Health

But Dariush Mozaffarian, MD, of Harvard's School of Public Health, says there may still be a role for omega-3 in the treatment and prevention of heart disease.

Mozaffarian studies fish oil and heart health but did not take part in either review.

"The good news is that the combined evidence from controlled trials confirms that fish oil reduces death from heart disease," he says. "The bad news is that effect appears smaller than we had thought -- about a 10% lowering of risk."

He says that many studies may have failed to show a benefit because participants did not take high enough doses of the supplements or because most were also taking other drugs to lower their heart attack and stroke risk.

SOURCES: Rizos, E.C. Journal of the American Medical Association, Sept. 12, 2012. Dariush Mozaffarian, MD, co-director, Program in Cardiovascular Epidemiology, Division of Cardiovascular Medicine, Brigham and Women's Hospital and Harvard Medical School; department of epidemiology, Harvard School of Public Health, Boston. David A. Friedman, MD, chief, Heart Failure Services, North Shore-LIJ Plainview Hospital, Plainview, N.Y. News release, JAMA. AHA: "Fish and Omega 3 Fatty Acids." Kwak, S.M. Archives of Internal Medicine, 2012.

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