Dietary fat and risk of coronary heart disease in men: cohort follow up study in the United States

Objective: To examine the association between fat intake and the incidence of coronary heart disease in men of middle age and older.  Design: Cohort questionnaire study of men followed up for six years from 1986.  Setting: The health professionals follow up study in the United States. Subjects: 43 757 health professionals aged 40 to 75 years free of diagnosed cardiovascular disease or diabetes in 1986. Main outcome measure: Incidence of acute myocardial infarction or coronary death. Results: During follow up 734 coronary events were documented, including 505 non-fatal myocardial infarctions and 229 deaths. After age and several coronary risk factors were controlled for significant positive associations were observed between intake of saturated fat and risk of coronary disease. For men in the top versus the lowest fifth of saturated fat intake (median = 14.8% v 5.7% of energy) the multivariate relative risk for myocardial infarction was 1.22 (95% confidence interval 0.96 to 1.56) and for fatal coronary heart disease was 2.21 (1.38 to 3.54). After adjustment for intake of fibre the risks were 0.96 (0.73 to 1.27) and 1.72 (1.01 to 2.90), respectively. Positive associations between intake of cholesterol and risk of coronary heart disease were similarly attenuated after adjustment for fibre intake. Intake of linolenic acid was inversely associated with risk of myocardial infarction; this association became significant only after adjustment for non-dietary risk factors and was strengthened after adjustment for total fat intake (relative risk 0.41 for a 1% increase in energy, P for trend <0.01). Conclusions: These data do not support the strong association between intake of saturated fat and risk of coronary heart disease suggested by international comparisons. They are compatible, however, with the hypotheses that saturated fat and cholesterol intakes affect the risk of coronary heart disease as predicted by their effects on blood cholesterol concentration. They also support a specific preventive effect of linolenic acid intake. (Author�s abstract)

In this study, the authors examined the association between dietary fat and cholesterol and risk of myocardial infarction in a large cohort of men in the United States. The health professionals follow up study began in 1986 when 51 529 health professionals aged 40 to 75 years completed a 131 item food frequency questionnaire and provided information about medical history, risk factors for heart disease, and dietary changes during the past 10 years. 43 757 eligible men were followed for incidence of coronary disease during the subsequent six years. In this large prospective study, strong and highly significant age adjusted associations were found between intakes of saturated fat, cholesterol, and trans fatty acids with risk of coronary disease. An independent inverse relation between intake of linolenic acid and risk of coronary disease was noted and support the hypothesis of a specific preventive effect of ALA. Although it has been suggested that the benefits of linolenic acid are due to its conversion to eicosapentaenoic acid, intake of marine n-3 fatty acids was not inversely associated with risk in our cohort, suggesting that the cardiovascular effects of linolenic acid may be different from those of the longer chain n-3 fatty acids. (Editor�s comments)