EFFECT OF VARIATIONS IN ORAL FAT AND CARBOHYDRATE LOAD ON POSTPRANDIAL LIPEMIA

In this study we assessed the acute effects of the consumption of vary ing amounts of fat and fructose on the magnitude of postprandial lipem ia. Subjects were studied after an overnight fast on four separate mor nings, ingesting in random order 5, 40, or 80 g fat, or 5 g fat plus 5 0 g fructose. Vitamin A (36 mg, or 120 000 U retinol) was also given a nd blood was drawn at frequent intervals over the next 10 h for measur ement of triacylglycerol and retinyl palmitate (RP) concentrations in plasma and the S-f > 400 and S-f 20-400 lipoprotein fractions. (S-f de notes flotation units.) In general, the postprandial triacylglycerol r esponse increased in plasma and in both lipoprotein fractions as a fun ction of both the baseline fasting triacylglycerol concentration and t he amount of fat ingested. However, no matter how high the fasting pla sma triacylglycerol concentration, there was no increase in the postpr andial triacylglycerol concentration in plasma or either lipoprotein f raction after the 5-g oral fat load. The results of the measurements o f RP concentration were somewhat similar in that there was a dose-depe ndent increase in the plasma and the S-f > 400 lipoprotein fraction in response to the higher fat loads. However, just the opposite was true in the S-f 20-400 Lipoprotein fraction, for which the increase in RP concentration was inversely related to the size of the fat load. The a ddition of 50 g fructose to the 5-g fat load also led to a significant increase in the RP concentration in plasma and in both lipoprotein fr actions, and the increase in the S-f 20-400 lipoprotein fraction after the addition of 50 g fructose to the 5-g fat load was approximately t hree times greater than that after 80 g fat. These data demonstrate th at the addition of either fat or fructose will accentuate the degree o f postprandial lipemia.