DIETARY-FAT INTAKE AND THE RISK OF CORONARY HEART-DISEASE IN WOMEN

Background The relation between dietary intake of specific types of fa t, particularly trans unsaturated fat, and the risk of coronary diseas e remains unclear. We therefore studied this relation in women enrolle d in the Nurses' Health Study. Methods We prospectively studied 80,082 women who were 34 to 59 years of age and had no known coronary diseas e, stroke, cancer, hypercholesterolemia, or diabetes in 1980. Informat ion on diet was obtained at base line and updated during follow-up by means of validated questionnaires. During 14 years of follow-up, we do cumented 939 cases of nonfatal myocardial infarction or death from cor onary heart disease. Multivariate analyses included age, smoking statu s, total energy intake, dietary cholesterol intake, percentages of ene rgy obtained from protein and specific types of fat, and other risk fa ctors. Results Each increase of 5 percent of energy intake from satura ted fat, as compared with equivalent energy intake from carbohydrates, was associated with a 17 percent increase in the risk of coronary dis ease (relative risk, 1.17; 95 percent confidence interval, 0.97 to 1.4 1; P=0.10). As compared with equivalent energy from carbohydrates, the relative risk for a 2 percent increment in energy intake from trans u nsaturated fat was 1.93 (95 percent confidence interval, 1.43 to 2.61; P<0.001); that for a 5 percent increment in energy from monounsaturat ed fat was 0.81 (95 percent confidence interval, 0.65 to 1.00; P=0.05) ; and that for a 5 percent increment in energy from polyunsaturated fa t was 0.62 (95 percent confidence interval, 0.46 to 0.85; P=0.003). To tal fat intake was not significantly related to the risk of coronary d isease (for a 5 percent increase in energy from fat, the relative risk was 1.02; 95 percent confidence interval, 0.97 to 1.07; P=0.55). We e stimated that the replacement of 5 percent of energy from saturated fa t with energy from unsaturated fats would reduce risk by 42 percent (9 5 percent confidence interval, 23 to 56; P<0.001) and that the replace ment of 2 percent of energy from trans fat with energy from unhydrogen ated, unsaturated fats would re; duce risk by 53 percent (95 percent c onfidence interval, 34 to 67; P<0.001). Conclusions Our findings sugge st that replacing saturated and trans unsaturated fats with unhydrogen ated monounsaturated and polyunsaturated fats is more effective in pre venting coronary heart disease in women than reducing overall fat inta ke. (C) 1997, Massachusetts Medical Society.