Intestinal cholesterol metabolism.

The handling of cholesterol by the intestine involves a balance between absorption, excretion and metabolism by gut microflora. Between 34-57% of dietary cholesterol is absorbed from the human intestine. Variables effecting the efficiency of cholesterol absorption include the absolute amount of cholesterol consumed, the presence of plant sterols, the fiber content of the diet, transit time and possibly the relative proportions of fatty acids in the diet. On average, 150 mg/day of cholesterol is excreted in the feces. Fecal cholesterol derives from biliary secretions into the intestine, sloughing of epithelial cells and unabsorbed dietary cholesterol. The major metabolic products of cholesterol in the gut are coprostanol, coprostanone, cholestanol, cholestanone and epicoprostanol. Bacterial metabolism of cholesterol can be influenced by diet as evidenced by significant variations among different population groups with different dietary habits. Altered patterns of intestinal bacterial metabolism of cholesterol may place persons at a higher risk of developing colonic disorders. Dairy products have been reported to influence the bacterial metabolism of cholesterol and possibly plasma cholesterol levels although the significance of these findings to overall cholesterol balance needs to be further defined.