Intestinal lipoprotein formation.

The average western diet contains approximately 40% of total calories as dietary fat or approximately 100 g of fat. The efficiency of the entire process of fat absorption can be judged by the fact that under normal conditions less than 5% of ingested fat is recovered in the stool. In the past several years, new concepts have greatly added to our understanding of the process by which dietary fat is digested, absorbed and processed in the intestinal epithelial cell for delivery to the body via the intestinal lymph and the portal venous system. These newer concepts include an understanding of the physical chemistry of lipids, the physiology of bile salts and the formation and metabolisms of lipoprotein all directly influencing the process of fat absorption. The present discussion will emphasize the formation of lipoproteins within the intestinal mucosa. New information suggests that the small intestinal mucosa is a quantitatively important source of lipoprotein constituents for systemic lipoproteins. This is hardly surprising when one considers the large quantities of lipid transversing the intestinal mucosa each day which must exit in the form of lipoproteins.