Fat loading experiments with the vitamins A and E suggest that in postprandial lipemia transfer/diffusion of chylomicron lipids to VLDL contributes to beta-VLDL formation

Vitamins A and E differ in hydrophobicity. When added to a fat load more or less specific labeling of chylomicrons and their remnants can be expected and this allows to approach the mechanism of postprandial lipemia from a ne w sight of view. Applied in a study in which 20 patients participated (eigh t patients with familial dysbetalipoproteinemia (FD), six patients with fam ilial combined hyperlipidemia (FCH) and six controls) we found that vitamin A, no longer paralleled the apo B-48 concentrations from 9 h after a fat l oad, especially in the remnant fraction with Sf 15-100. Qualitatively, the distribution of vitamin A to the more dense fractions mirrored that of vita min E, but the latter was more rapid. Both vitamins at the maximum of remna nt-accumulation, at 14 h after the fat load, correlated with the cholestero l content of the remnant fraction. For vitamin E there was a similar concen tration dependent distribution to all other lipoprotein fractions. The resu lts confirm our view that the lipoprotein mechanism can be regarded as a dy namic system. During regular episodes following the meals, exogenous fat is , like the vitamins, distributed over all endogeneously formed lipoproteins . This transfer process results in the formation of P-VLDL and contributes to the pathogenesis of FCH and FD. (C) 1998 Elsevier Science Ireland Ltd. A ll rights reserved.