A biochemical and morphologic study of very low density lipoproteins in carbohydrate-induced hypertriglyceridemia.

On a high carbohydrate, fat-free diet, control and hypertriglyceridemic subject had a three-fold increase in d < 1.006, very low density lipoprotein (VLDL) triglyceride, and somewhat lesser increases in VLDL cholesterol and protein. Cholesterol and protein in 1.006 < d < 1.21 lipoprotein decreased in a reciprocal fashion, suggesting that these components might have been utilized in VLDL production. Electron microscope studies demonstrated a significant increase in the size of lipoprotein particles of the VLDL class and, in three of four subjects, an apparent increase in particle number. The change in particle size correlated with an increase in the triglyceride/protein ratio of the d < 1.006 lipoprotein. Hypertriglyceridemic individuals differed from the control subjects in that they had greater absolute increases in VLDL triglyceride, cholesterol, and protein, and greater decreases in 1.006 < d < 1.21 cholesterol and protein. In addition, they had larger VLDL particles with a higher triglyceride/protein ratio, both before the study and at the peak of the carbohydrate effect. The data suggest that the increase in plasma triglycerides induced by a high carbohydrate diet is usually due to the appearance in plasma of both greater numbers of VLDL particles and larger particles that are relatively richer in triglyceride content than those isolated during the basal state.