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

Background: Experimental studies in laboratory animals and humans suggest t hat alpha-linolenic acid (18:3n-3) may reduce the risk of arrhythmia. Objective: The objective was to examine the association between dietary int ake of alpha-linolenic acid and risk of fatal ischemic heart disease (IHD). Design: This was a prospective cohort study. The intake of alpha-linolenic acid was derived from a 116-item food-frequency questionnaire completed in 1984 by 76283 women without previously diagnosed cancer or cardiovascular d isease. 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, sta ndard coronary risk factors, and dietary intake of linoleic acid and other nutrients, a higher intake of alpha-linolenic acid was associated with a lo wer relative risk (RR) of fatal IHD; the RRs from the lowest to highest qui ntiles were 1.0, 0.99, 0.90, 0.67, and 0.55 (95% CI: 0.32, 0.94; P for tren d = 0.01). For nonfatal myocardial infarction there was only a modest, nons ignificant 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 alpha-linolenic acid, w as associated with reduced risk of fatal IHD when women who consumed this f ood greater than or equal to 5-6 times/wk were compared with those who rare ly 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 alp ha-linolenic acid is protective against fatal IHD. Higher consumption of fo ods such as oil-based salad dressing that provide polyunsaturated fats, inc luding alpha-linolenic acid, may reduce the risk of fatal IHD.