In previous work we identified a transfer/diffusion process occurring in the postprandial state that more or less contributes to the accumulation of
beta-VLDL in
familial dysbetalipoproteinemia (FD). Here we present a new theoretical concept underlying
chylomicron processing developed on the basis of extended quantitative analyses of fat loading experiments, with both
vitamins A and E, performed in patients with
familial combined hyperlipidemia (FCH) in comparison to patients with FD and control subjects. Recovery of
triglycerides from the fat load in the plasma
triglyceride pool was <4%, indicating a very effective lipolysis process with an active remnant generation.
Vitamin A from the fat load was, over 48 h, quantitatively recovered in the plasma
lipoprotein pool;
vitamin E was recovered to 2241%. Nevertheless, transfer/diffusion of both
vitamins showed similar patterns. At equilibrium, their contents correlated strongly with the
lipoprotein concentrations, the slopes being similar for control subjects and both groups of patients. Only in those FD patients with the highest
lipid values, did the
vitamin A/
lipoprotein mass ratio in the Sf>100 fraction deviate from the total group mean. In the Sf 15-100 fraction, most specific for 'remnants',
vitamin A/
cholesterol ratios for all subjects were uniform proving that
beta-VLDL formation is a thermodynamic process regulated by concentration gradients and the lipophilicity of
lipoprotein constituents, not a typical feature for patients with FD. In patients with FD,
vitamin A in the plasma pool was recovered excessively (276%) in line with recognition in various pools as a result of the transfer/diffusion process in plasma.