What is the main endogenous source of cholesterol?

• A. Liver (Endogenous): 85%
• B. Diet (Exogenous): 15%
• C. Adrenal glands
• D. Intestines

Answer: (A)

Cholesterol in the body comes from two main routes: what the body makes on its own (endogenous) and what is obtained from the diet (exogenous). The liver is the central site for endogenous cholesterol synthesis, producing cholesterol through the mevalonate pathway with the enzyme HMG-CoA reductase acting as the key control point. This internal production supplies cholesterol for cell membranes, steroid hormone production, and bile acids, and it’s what’s packaged into VLDL for distribution in the bloodstream. Dietary cholesterol is absorbed from food and contributes to the pool, but it is separate from this major internal production. The adrenal glands and intestines participate in cholesterol handling, but they are not the primary source of endogenous cholesterol. Therefore, the liver is the main endogenous source.