Women in the highest intake group had a 46 per cent reduced risk of dying from sudden cardiac death compared to women in the lowest intake group, said researchers at the American Heart Association's annual meeting (poster 3604).
And women who consumed the most ALA were 21 per cent less likely to die from coronary heart disease than women in the lowest ALA intake group.
The study supports the heart health benefits of ALA, a form of omega-3 found in green leafy vegetables, some nuts, canola and flaxseed oil. It is converted by the body into DHA and EPA but some scientists have questioned whether it is as valuable in supplement form as the concentrated DHA and EPA gained from fish oils.
However the new results seem to confirm that ALA, like fish oils, does protect people from dying from heart disease, possibly by preventing life-threatening rhythm disturbances (arrhythmias).
"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," suggested the study's lead author Christine M. Albert, assistant professor of medicine at Harvard University Medical School, Boston.
Two recent studies have also suggested that taking fish oil supplements and eating fatty fish can reduce the risk of developing abnormal heart rhythms (arrhythmias).
However Albert noted: "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."
The new 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 a 16-year follow-up period.
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.
According to Albert, the study suggests that the higher a woman's ALAintake, the greater the benefit. However, she underlined that this is an observational study and further studies are needed before recommending certain amounts of dietary ALA.
But the study may help to boost the market for plant-derived omega-3 fatty acids, such as flax, which still only makes up 4 per cent of the €160 million European omega-3 market.
Another study out this month found that a diet rich in alpha-linolenic acid from walnuts, walnut oil and flaxseed oil not only lowered bad cholesterol but also decreased markers for blood vessel inflammation in men and women at risk of heart disease.