Dietary intake of α-linolenic acid and risk of fatal ischemic heart disease among women

Background: Experimental studies in laboratory animals and humans suggest that α-linolenic acid (18:3n-3) may reduce the risk of arrhythmia. Objective: The objective was to examine the association between dietary intake of α-linolenic acid and risk of fatal ischemic heart disease (IHD). Design: This was a prospective cohort study. The intake of α-linolenic acid was derived from a 116-item food-frequency questionnaire completed in 1984 by 76283 women without previously diagnosed cancer or cardiovascular disease. Results: During 10 y of follow-up, we documented 232 cases of fatal IHD and 597 cases of nonfatal myocardial infarction. After adjustment for age, standard coronary risk factors, and dietary intake of linoleic acid and other nutrients, a higher intake of α-linolenic acid was associated with a lower relative risk (RR) of fatal IHD; the RRs from the lowest to highest quintiles were 1.0, 0.99, 0.90, 0.67, and 0.55 (95% CI: 0.32, 0.94; P for trend = 0.01). For nonfatal myocardial infarction there was only a modest, nonsignificant trend toward a reduced risk when extreme quintiles were compared (RR: 0.85; 95% CI: 0.61, 1.19; P for trend = 0.50). A higher intake of oil and vinegar salad dressing, an important source of α-linolenic acid, was associated with reduced risk of fatal IHD when women who consumed this food ≥5-6 times/wk were compared with those who rarely consumed this food (RR: 0.46; 95% CI: 0.27, 0.76; P for trend = 0.001). Conclusions: This study supports the hypothesis that a higher intake of α-linolenic acid is protective against fatal IHD. Higher consumption of foods such as oil-based salad dressing that provide polyunsaturated fats, including α-linolenic acid, may reduce the risk of fatal IHD.