Dietary fat intake and the risk of coronary heart disease in women.
Dietary fat intake and the risk of coronary heart disease in women.
Year: 1997
Authors: F B Hu, M J Stampfer, J E Manson, E Rimm, G A Colditz, B A Rosner, C H Hennekens, W C Willett.
Publication Name: New England Journal of Medicine.
Publication Details: Volume 337; Page 1491.
Abstract:
Low-fat, high-carbohydrate diets have been widely recommended as a way to reduce the risk of coronary heart disease (CHD) because populations with low intakes of saturated and total fat tend to be at low risk and because saturated fat increases low-density lipoprotein (LDL) cholesterol levels. However, low-fat, high-carbohydrate diets also reduce high-density lipoprotein (HDL) cholesterol levels and raise fasting levels of triglycerides. Because low levels of HDL cholesterol and high levels of triglycerides independently increase risk, the value of replacing fat in general with carbohydrates has been questioned. Replacing saturated fat and trans unsaturated fat with unhydrogenated unsaturated fats has clear beneficial effects on blood lipids and thus provides an alternative strategy for reducing the risk of CHD. The relationship between dietary intake of specific types of fat, particularly trans unsaturated fat, and the risk of coronary disease was assessed in women enrolled in the Nurses’ Health Study. This study included 80,082 women who were 34 to 59 years of age and had no known CHD, stroke, cancer, hypercholesterolemia, or diabetes in 1980. Information on diet was obtained at base line and updated during follow-up by means of validated questionnaires. During 14 years of follow-up, 939 cases of nonfatal myocardial infarction or death from coronary heart disease were recorded. Each increase of 5 percent of energy intake from saturated fat and from trans fatty acids, as compared with equivalent energy intake from carbohydrates, was associated with a 17 percent increase in the risk of CHD. As compared with equivalent energy from carbohydrates, the relative risk for a 2 percent increment in energy intake from trans unsaturated fat was 1.93; for a 5 percent increment in energy from monounsaturated fat was 0.81; and that for a 5 percent increment in energy from polyunsaturated fat was 0.62. Total fat intake was not significantly related to the risk of CHD. The replacement of 5 percent of energy from saturated fat with energy from unsaturated fats could reduce risk of CHD by 42 percent and the replacement of 2 percent of energy from trans fat with energy from unhydrogenated, unsaturated fats would reduce risk by 53 percent. The results of this large long term study suggest that a higher dietary intake of saturated fat and trans unsaturated fat is associated with an increased risk of CHD, whereas a higher intake of monounsaturated and polyunsaturated fats is associated with a decreased risk. Because of the opposite effects of different fats on incidence, total fat intake was not significantly related to the risk of CHD. The inverse association between dietary PUFA and CHD is consistent with the results of numerous metabolic studies that showed strong cholesterol-lowering effects of vegetable oils rich in linoleic acid when they were substituted for saturated fat in the diet. The positive association of CHD with the intake of trans unsaturated fat is consistent with the results of most previous studies. The findings of this investigation reinforce evidence from metabolic studies that replacing saturated fat and trans unsaturated fat in the diet with unhydrogenated monounsaturated and polyunsaturated fats favorably alters the lipid profile, but that reducing overall fat intake has little effect.
