A sudden increase in
dietary carbohydrate invariably increases the plasma levels of
very low density lipoprotein (VLDL) and
triglyceride. The present studies were designed to test the hypothesis that
dietary carbohydrate-induced
hypertriglyceridemia need not occur. In the first study we fed gradually increasing amounts of
carbohydrate and gradually decreasing amounts of fat to eight subjects. The usual American diet (40% fat, 45%
carbohydrate, and 15%
protein) was followed in sequence by four diets in a phased regimen, the
carbohydrate increasing by 5% of total calories and the fat content decreasing by 5% for each dietary period. In the last dietary period (phase 4), 20% of the energy was in the form of fat and 65% in the form of
carbohydrates; the
cholesterol content was 100 mg/day. Throughout the study, plasma
triglyceride and
VLDL triglyceride levels did not change significantly. The plasma total and
low density lipoprotein (
LDL) cholesterol levels were greatly reduced, by 15% and 22%, respectively (p = 0.004). Plasma
high density lipoprotein (
HDL) cholesterol levels decreased concomitantly. In the second study, after a washout period six of the subjects were initially fed the phase 4 high-
carbohydrate diet for a 10-day period. The plasma
triglyceride concentration increased over baseline levels by 47%, and
VLDL triglyceride levels increased by 73%. We conclude that although a sudden increase in
dietary carbohydrate increases the plasma
triglyceride level, patients gradually introduced to a high-
carbohydrate,
low-fat diet may achieve a significant reduction of plasma total and
LDL cholesterol without developing
carbohydrate-induced
hypertriglyceridemia.