A prospective study of dietary glycemic load, carbohydrate intake, and risk of coronary heart disease in US women

Background: Little is known about the effects of the amount and type of carbohydrates on risk of coronary heart disease (CHD). Objective: The objective of this study was to prospectively evaluate the relations of the amount and type of carbohydrates with risk of CHD. Design: A cohort of 75 521 women aged 38-63 y with no previous diagnosis of diabetes mellitus, myocardial infarction, angina, stroke, or other cardiovascular diseases in 1984 was followed for 10 y. Each participant's dietary glycemic load was calculated as a function of glycemic index, carbohydrate content, and frequency of intake of individual foods reported on a validated food- frequency questionnaire at baseline. All dietary variables were updated in 1986 and 1990. Results: During 10 y of follow-up (729 472 person-years), 761 cases of CHD (208 fatal and 553 nonfatal) were documented. Dietary glycemic load was directly associated with risk of CHD after adjustment for age, smoking status, total energy intake; and other coronary disease risk factors. The relative risks from the lowest to highest quintiles of glycemic load were 1.00, 1.01, 1.25, 1.51, and 1.98 (95% CI: 1.41, 2.77 for the highest quintile; P for trend < 0.0001). Carbohydrate classified by glycemic index, as opposed to its traditional classification as either simple or complex, was a better predictor of CHD risk. The association between dietary glycemic load and CHD risk was most evident among women with body weights above average [ie, body mass index (in kg/m²) ≥ 23]. Conclusion: These epidemiologic data suggest that a high dietary glycemic load from refined carbohydrates increases the risk of CHD, independent of known coronary disease risk factors.