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

Abstract

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 ajustment 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. Key messages: Diets high in saturated fat and cholesterol are associated with an increased risk of coronary disease, but these adverse effects are at least in part explained by their low fibre content and associations with other risk factors Diets high in linolenic acid (N-3 fatty acid from plants) are associated with a reduced risk of coronary heart disease, independently of other dietary and non-dietary risk factors Uncertainty remains on the optimal amount of polyunsaturated fat in the diet for prevention of coronary heart disease Benefits of reducing intakes of saturated fat and cholesterol are likely to be modest unless accompanied by an increased consumption of foods rich in fibre