A fatty-like, white crystalline substance that is a steroid lipid found in large concentrations in the blood, brain, liver, muscle, spinal cord, and other organs and tissues, with liver being the most important site for its synthesis. Both the liver and dietary intake (e.g., dairy products, fish, meat, poultry) are the main sources of cholesterol. After being synthesized from acetic acid, it then becomes an important precursor for the synthesis of vitamin D3, various steroid hormones (e.g., cortisol in the adrenal glands), and the sex hormones progesterone, oestrogen, and testosterone. Also, cholesterol provides stability for the membranes of cells, seems to play a role in immune system protection against cancer and in modulating synaptic activity in the brain. Myelin is composed of 15% cholesterol and 20% protein, and thus it has a role to play in brain development as well as with regard to sexual differentiation. Cholesterol is transported out of the bloodstream for excretion by high-density lipoprotein (HDL), and carried back by low-density lipoprotein (LDL) for use by various body cells. Large amounts of HDL cholesterol (the ‘good’ cholesterol) are associated with better health.
See Acetic acid, Adrenal glands, Cardiovascular accidents (CVAs), Corticosteriods, Cortisol, Estrogen, Fatty acid, Hormones, Lipids, Myelin, Progesterone, Testosterone, Steroid hormones