This document discusses cholesterol metabolism and ways to lower cholesterol levels. It covers the sources of cholesterol from diet and de novo synthesis. The key enzyme in cholesterol synthesis, HMG CoA reductase, is regulated both short-term by phosphorylation and long-term by SREBP-2 which responds to cellular sterol levels. Statins are commonly used to lower cholesterol by decreasing the activity of HMG CoA reductase. Other strategies mentioned include bile sequestering agents which bind bile acids, increasing cholesterol use to make more bile acids, and niacin which inhibits VLDL excretion from the liver.