Background: It has been hypothesized that a diet containing n-3 fatty acids from fish reduces the risk of coronary heart disease, but few large epidemiologic studies have examined this question.
Methods: In 1986, 44,895 male health professionals, 40 to 75 years of age, who were free of known cardiovascular disease completed detailed and validated dietary questionnaires as part of the Health Professionals Follow-up Study. During six years of follow-up, we documented 1543 coronary events in this group: 264 deaths from coronary disease, 547 nonfatal myocardial infarctions, and 732 coronary-artery bypass or angioplasty procedures.
Results: After controlling for age and several coronary risk factors, we observed no significant associations between dietary intake of n-3 fatty acids or fish intake and the risk of coronary disease. For men in the top fifth of the group in terms of intake of n-3 fatty acids (median, 0.58 g per day), the multivariate relative risk of coronary heart disease was 1.12 (95 percent confidence interval, 0.96 to 1.31), as compared with the men in the bottom fifth (median, 0.07 g per day). For men who consumed six or more servings of fish per week, as compared with those who consumed one serving per month or less, the multivariate relative risk of coronary disease was 1.14 (95 percent confidence interval, 0.86 to 1.51). The risk of death due to coronary disease among men who ate any amount of fish, as compared with those who ate no fish, was 0.74 (95 percent confidence interval, 0.44 to 1.23), but the risk did not decrease as fish consumption increased.
Conclusions: Although the possibility of residual confounding by unmeasured factors cannot be entirely excluded, these data suggest that increasing fish intake from one to two servings per week to five to six servings per week does not substantially reduce the risk of coronary heart disease among men who are initially free of cardiovascular disease.