Postprandial studies on dietary cholesterol in human subjects using stableisotopes and gas chromatography mass spectrometry analysis

We hypothesized that intestinal absorption and postprandial re-secretion of dietary cholesterol may be a particularly complex process in humans. To te st this hypothesis, we used deuterium-enriched cholesterol to specifically label meal cholesterol and developed an improved method for quantitative me asurement of traces of deuterated cholesterol as well as cholesterol with r eference to two different internal standards by gas chromatography-mass spe ctrometry (GC-MS) measurement. In the first study, a group of healthy subje cts ingested a single test meal containing deuterated cholesterol with a 7 h postprandial follow-up. In the second one, a group of healthy subjects in gested a first test meal containing deuterated cholesterol and a follow-up was performed during three consecutive test meals and later until 72 h. The most striking observations were that the occurrence of dietary cholesterol in chylomicrons is not concomitant to triglycerides and is very low after a single meal while most dietary cholesterol is re-secreted in chylomicrons after a second, and even a third, fat test meal. The data obtained show th at the re-secretion of dietary cholesterol from the small intestine is a sl ow and complex process in humans. (C) 1998 Elsevier Science Ireland Ltd. Al l rights reserved.