Carbohydrate nutrition, glycaemic load, and plasma lipids: the Insulin Resistance Atherosclerosis Study

Abstract

We evaluated the relationship of carbohydrate nutrition and selected food groups with lipids using data from the Insulin Resistance Atherosclerosis Study (IRAS Exam I, 1992-1994). A total of 1026 middle-aged adults with normal or impaired glucose tolerance had complete data on fasting lipids and usual dietary intake from an interviewer-administered, validated food frequency questionnaire. Published glycaemic index (GI) values were assigned to food items and average dietary GI and glycaemic load (GL) were calculated per participant. Intake of carbohydrates differed by gender, men consuming more absolute digestible carbohydrates with higher GI and GL than women. In multivariate models adjusting for energy intake, in men, GL and carbohydrates were associated positively with total and LDL cholesterol, and inversely with HDL. In women, associations were limited to triglycerides. We estimated that a 100 g higher intake in GL or carbohydrates was associated with a 7-8 mg/dL higher total or LDL cholesterol level in men, and a 13-17 mg/dL higher triglyceride level in women. In the combined sample, GL and carbohydrates were consistently associated with all lipid levels and GI was inversely associated with HDL cholesterol. Our findings underscore the importance of carbohydrate nutrition for plasma lipids.