Effects of graded amounts (0-50 g) of dietary fat on postprandial lipemia and lipoproteins in normolipidemic adults.

Eight normolipidemic males ingested on separate days and in a random order five mixed meals containing 0, 15, 30, 40, or 50 g fat. Fasting and postprandial blood samples were obtained for 7 h and chylomicrons and lipoproteins were isolated. The nonfat and 15-g fat meals did not generate noticeable postprandial variations except for HDL phospholipids (P < 0.05). The serum and chylomicron triacylglycerol responses obtained after the meals correlated positively with the amount of fat ingested and peaked after 2-3 h. Serum free cholesterol and phospholipids increased and esterified cholesterol decreased postprandially in a dose-response manner. At the same time, triacylglycerol-rich-lipoprotein triacylglycerols, esterified cholesterol, LDL free cholesterol, HDL triacylglycerols, phospholipids, and free cholesterol increased whereas LDL and HDL esterified cholesterol decreased when the amount of ingested fat increased. The data showed that increasing the amount of fat in the usual range of ingestion (0-50 g) led to stepwise increases in the postprandial rise of chylomicron and serum triacylglycerols and induced marked changes in serum lipoproteins postprandially. The existence of a no-effect level of dietary fat (15 g) on postprandial lipemia and lipoproteins in healthy adults was shown.