To evaluate the transformation of cholesterol into coprostanol in the presence of probiotic bacteria, Chiang et al. [101] have shown that cholesterol dehydrogenase/isomerase produced by bacteria such as I Sterolibacterium denitrificans i catalyzes the transformation of cholesterol to cholest-4-en-3-one during biotransformation of cholesterol to coprostanol. Several possible mechanisms, such as cholesterol assimilation by growing-bacteria, cholesterol binding on to the probiotic cells, cholesterol integration into the host cell membrane, BSH-mediated bile deconjugation, and cholesterol coprecipitation with deconjugated bile, have been proposed. A significant decrease in their serum cholesterol, LDL, and total cholesterol was noted, while HDL cholesterol increased marginally [79]. Consequently, the deconjugation of bile salts might cause reduction in serum cholesterol levels (a) by raising the demand for cholesterol required for the I de novo i synthesis of bile acids to compensate for those lost via feces or (b) by lowering the cholesterol solubility and subsequent absorption through the gut lumen. [Extracted from the article]