Women who reported eating diets rich in oils containing alpha-linolenic acid (ALA) seemed to have a lower risk of dying from heart disease and sudden cardiac death than women whose diets are low in the plant-derived fatty acid, researchers reported at the American Heart Association’s Scientific Sessions 2004.
The study’s lead author, Christine M. Albert, M.D., M.P.H., assistant professor of medicine at Harvard University Medical School, Boston, said some data suggest that certain types of fatty acids may help protect people from dying from heart disease by preventing life-threatening rhythm disturbances (arrhythmias).
This association with fatty acids and arrhythmias was found in the Nurse’s Health Study which asked participants what they ate.
“A clinical trial that randomly assigns people to ALA supplements or to a diet high in ALA would be needed to know for sure that ALA lowers risk of coronary heart disease and sudden cardiac death,” Albert said.
ALA is found in a variety of green leafy vegetables, some types of nuts, canola oil, flaxseed oil and in flaxseed supplements. Some salad dressings and margarines also contain ALA.
“In this study, we examined whether ALA was associated with a lower risk of dying from heart disease or sudden cardiac death, which is death resulting from an abrupt loss of heart function,” she said. “Sudden cardiac death is usually the result of a fatal rhythm disturbance. So, if this fat were to prevent sudden cardiac death, it would support the hypothesis that these oils were preventing fatal arrhythmias. During the 16 years of follow-up, women who had higher ALA intake had a significantly lower risk of dying from sudden cardiac death or coronary heart disease.”
The study included 76,763 women participating in the Nurse’s Health Study who had completed a food questionnaire in 1984. The food questionnaire was updated every four years.
During the follow-up, 169 women suffered a sudden cardiac death, 564 had a coronary artery disease death and 1,325 had non-fatal heart attacks.
Researchers separated the women studied into five categories of increasing ALA intake. The average intake varied from 0.7 grams a day in the lowest intake category to a high of 1.5 grams each day in the highest. Women in the highest intake group had a 46 percent reduced risk of dying from sudden cardiac death compared to women in the lowest intake group. Women who consumed the most ALA were 21 percent less likely to die from coronary heart disease than women in the lowest ALA intake group.
ALA intake was not associated with non-fatal heart attacks.
According to Albert, the study suggests that the higher a woman’s ALA intake, the greater the benefit. However, this is an observational study and further studies are needed before making a recommendation that women should consume a certain amount of ALA in their diets.