Cholesterol, a major sterol is the precursor for steroid hormones, bile acid and vitamin in mammals and coordinates endocytosis. It complexes with protein to form lipoproteins for transport in blood. It exists either as high-density lipoprotein (HDL) or low-density lipoprotein (LDL). HDL also called good cholesterol has less lipid content. LDL or bad cholesterol has high lipid content. Statin inhibition of HMG-CoA reductase enzyme in the cholesterol biosynthesis pathway controls elevated cholesterol levels in atherosclerosis and hypercholesterolemia. Low levels of cholesterol results in hypothyroidism, familial hypobetalipoproteinemia and liver disease. Imbalance of cholesterol homeostasis and intracellular cholesterol levels play a key role in cancer development. High cholesterol levels favor breast cancer progression.

Cholesterol has been used:

• as a medium supplement in chorionic villous tissue culture form placenta
• as a component of hormone pellet for implantation in mice ovary
• for inducing expression of immunity-related GTPase M (IRGM) in human monocytic cell line, THP-1

Major component of all biological membranes; ~25% of total brain lipid is cholesterol.