Acute effects of the pattern of fat ingestion on plasma high density lipoprotein components in man

Since Apoprotein A-I (apo A-I) is partially synthesized in the intestine and is secreted into plasma via chylomicrons, we have tested the effects of the daily distribution of fat intake on the concentration and composition of plasma high density lipoprotein (HDL). Ten normal subjects ingested 136 g fat either as a single load (SL) at 0 h or in 6 divided doses from 0 to 10 h (DL). Serial blood samples were obtained over a 24-h period. Studies were performed 7 days apart using a double crossover design and paired comparisons. HDL apo A-I increased during DL (+11% at 9 h, P < 0.01) but was not significantly altered after SL. The HDL Apo A-II concentration did not change. HDL cholesterol decreased significantly (-4 to -7%) during postprandial lipaemia in both phases of the study. Apo A-I and A-II were detected in lipoproteins of d < 1.006 during alimentary lipaemia but not in fasting plasma. These results indicate that HDL apo A-I increases when fat intake is distributed throughout the day (DL), perhaps due to intestinal production of particles with a higher protein/lipid ratio during DL than after a large bolus of oral lipid (SL). Alimentary lipaemia is associated with acute alterations in HDL components including a transient reduction in HDL cholesterol and an increase in the apo A-I/A-II ratio during DL.