The acute effect of prolonged walking and dietary changes on plasma lipoprotein concentrations and high-density lipoprotein subfractions.

The effect of diet on exercise-induced changes in the plasma concentrations of lipoproteins was examined in six healthy male subjects during walks of 37 km on each of four successive days. With a high-carbohydrate diet (85% of the calories as carbohydrate) there was an increase (P less than .05) in the concentration of very-low-density lipoprotein (VLDL)-cholesterol and VLDL-triglyceride and a decrease (P less than .01) in the concentration of high density lipoprotein (HDL)-cholesterol, due mainly to a decrease in HDL3-cholesterol (P less than .01), and HDL-protein (P less than .001). In contrast, a high-fat diet (75% fat) produced a decrease (P less than .01) in the concentration of VLDL-cholesterol and VLDL-triglyceride with increases (P less than .01) in HDL-protein concentration and in HDL-cholesterol concentrations that arose largely from an increase (P less than .001) in HDL2-cholesterol. Gradient gel electrophoretic analysis showed an increase (P less than .01) in the relative concentration of HDL2b (subspecies of diameter 10.57 nm) with a decrease (P less than .01) in the concentration of HDL2a (9.16 nm) plus HDL3a (8.44 nm) with the high-fat diet, but no significant or consistent change with the high-carbohydrate diet. There was no change in the level of the apolipoprotein E-rich HDL subfraction with either diet. Plasma lecithin:cholesterol acyltransferase activity decreased (P less than .05) with the high-fat diet but not with the high-carbohydrate diet. Thus, diet can strongly influence the changes that occur in plasma lipoprotein concentrations during prolonged low-intensity exercise.