Glycaemic index as a determinant of serum HDL-cholesterol concentration

Background Diet influences the prevalence of coronary heart disease (CHD). Insulin sensitivity and concentrations of HDL cholesterol, two metabolic predictors of CHD, are also influenced by diet. Dietary carbohydrates with a high glycaemic index cause a high postprandial glucose and insulin response, and are associated with decreased insulin sensitivity and an increased risk of CHD. This study examined whether the glycaemic index or dietary carbohydrates is a determinant of serum HDL-cholesterol concentrations. Method Dietary, anthropometric, and biochemical data from the 1986-87 Survey of British Adults (n=2200) were reanalysed by a multiple regression model, which examined the relation between serum total cholesterol, HDL-cholesterol, and calculated LDL-cholesterol concentrations and various dietary characteristics, including the type of carbohydrate, the glycaemic index, and fat intake. Findings Among the 1420 participants with complete data, there was a significant negative relation between serum HDL-cholesterol concentration and the glycaemic index of the diet for both men (regression coefficient -0.00724 [95% CI -0.0101 to -0.00434], p=0.02) and women (-0.01326 [-0.0162 to -0.0102], p<0.0001). No other significant relation was found with total cholesterol or LDL-cholesterol concentration or with any other dietary carbohydrate or fat constituent. Interpretation In a cross-sectional study of middle-aged adults, the glycaemic index of the diet was the only dietary variable significantly related to serum HDL-cholesterol concentration. Thus, the glycaemic index of the diet is a stronger predictor than dietary fat intake of serum HDL-cholesterol concentration.