Alpha-Linolenic Acid Intake Inversely Associated With Cardiac Events

Peggy Peck

November 11, 2004

Nov. 11, 2004 (New Orleans) -- A new analysis from the Nurses' Health Study suggests that women who consume a diet rich in alpha-linolenic acid (ALA) can significantly reduce the risk of sudden cardiac death, perhaps by lessening the risk of ventricular fibrillation or ventricular tachycardia.

The findings were reported here at the American Heart Association 2004 Scientific Sessions.

Lead researcher Christine M. Albert, MD, PhD, assistant professor of medicine at Harvard University Medical School in Boston, Massachusetts, told Medscape, "We postulate that ALA is anti-arrhythmic.... ALA doesn't prevent heart attacks, but it may prevent or calm the arrhythmias that often cause heart attacks."

In the study, women who consumed the highest levels of ALA -- defined as approximately 1.5 g per day -- "had a 46% lower risk of sudden cardiac death than women who consumed the least amount of [ALA], which was just over half a gram a day." Dr. Albert said 1.5 g equals "about two capfuls of flaxseed oil or a handful of walnuts."

ALA is a short-chain omega-3 fatty acid that can be elongated to the long-chain omega-3-fatty acids -- eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) -- found in fish. "While both men and women can convert short-chain omega-3 to long chain, there are data that suggest women do this more efficiently," Dr. Albert said. Moreover, ALA may have anti-arrhythmic effects in addition to its ability to convert into EPA and DHA, she said.

Dr. Albert and colleagues examined dietary intake of ALA and a possible association with sudden cardiac death, fatal coronary heart disease (CHD), and nonfatal myocardial infarction (MI) among the 76,763 healthy women enrolled in the Nurses' Health Study in 1984. The women completed food frequency questionnaires at baseline and every four years thereafter. During 16 years of follow-up, there were 169 sudden cardiac deaths, 564 fatal CHDs, and 1,325 nonfatal MIs.

After controlling for known risk factors, exercise, history of prior cardiovascular disease, aspirin use, trans-fat consumption and ratio of polyunsaturated to saturated fat, ALA intake was inversely associated with risk of sudden cardiac death and fatal CHD.

Compared with women in the lowest quintile for ALA consumption, women in the highest quintile had a 21% reduced risk of fatal CHD as well as a 46% reduction in risk of sudden cardiac death, Dr. Albert said.

"This is an observation, so we can only report an association between [ALA] consumption and heart disease," Dr. Albert said. She noted that earlier observations -- such as the observed cardioprotective effect of estrogen -- were proven wrong when tested in a randomized, placebo controlled study. "We need such a randomized trial to confirm this observation," she said.

Sidney Smith, MD, director of the Center for Cardiovascular Science and Medicine at the University of North Carolina in Chapel Hill, and a spokesperson for the American Heart Association, told Medscape that the findings support a theory that many researchers in preventive cardiology have proposed: ALA can be as beneficial as the omega-3 fatty acids found in fish. The American Heart Association recommends that patients consume at least two servings of fish a week as part of a heart-healthy diet.

Noting his own belief in the value of ALA, Dr. Smith said, "I crush walnuts and sprinkle them on my cereal every morning." Dr. Smith was not involved in the study.

Dr. Albert also noted that in addition to walnuts, flaxseed oil, and flaxseed supplements, "green leafy vegetables -- especially kale -- canola oil, salad dressings, some margarines, and almonds are also a source of ALA."

AHA 2004 Scientific Sessions: Abstract 3604. Presented Nov. 8, 2004.

Reviewed by Gary D. Vogin, MD

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