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Cholesterol is a sterol, a type of lipid that is a combination of a steroid and alcohol. It is found in the cell membranes of all body tissues and is transported in the blood plasma of animals. The term "cholesterol" originates from the Greek words "chole-" (bile) and "stereos" (solid), reflecting its initial discovery in solid form in gallstones in 1784.  In the body, cholesterol exists either in its free form or as cholesterol esters, where a fatty acid chain (typically 10-20 carbons in length) is attached to the cholesterol ring. These esters, due to their synthesis mechanism, often contain high proportions of polyunsaturated fatty acids and are less soluble in water than free cholesterol, making them more hydrophobic. Cholesterol plays vital roles in the body. It is crucial for the structure of cell membranes and lipid metabolism. As a biosynthetic precursor, it is essential for the production of bile acids, vitamin D, and steroid hormones, including glucocorticoids, estrogens, progesterones, androgens, and aldosterone. It also contributes significantly to the development and function of the central nervous system, signal transduction, and sperm development. Cholesterol distribution within the body is not uniform. It is predominantly found in plasma membranes, where it constitutes a significant portion of the lipid content. Conversely, organelles like mitochondria and the endoplasmic reticulum have very low cholesterol content. The brain, containing the highest proportion of cholesterol, accounts for about a quarter of the body's total free cholesterol. Cholesterol esters are the primary form of cholesterol transport in plasma and serve as a biologically inert storage form. They are carried throughout the body via lipoprotein particles, with the largest lipoproteins, chylomicrons, primarily transporting fats and cholesterol from the intestinal mucosa to the liver. In the liver, these are converted into low-density lipoprotein (LDL) particles, which carry triglycerides and cholesterol to other body cells. The size and number of LDL particles play a crucial role in health, as a high number of small LDL particles are associated with atherosclerosis, a major contributor to coronary heart disease and other cardiovascular diseases. The relationship between cholesterol levels and atherosclerosis is complex. Total cholesterol levels alone do not always correlate with atherosclerosis risk; instead, the pattern of cholesterol transport (e.g., LDL particle size and number, HDL particle size) is more indicative of disease risk. Furthermore, the presence of asymmetric dimethylarginine (ADMA), which down-regulates nitric oxide production in the endothelium, can exacerbate the risk when associated with high levels of oxidized LDL. Given its critical roles and implications in health, cholesterol remains a significant focus in scientific and dietary research, particularly in understanding the optimal balance needed for maintaining good health.

Chemical and Physical Properties

Computed Properties

Source: PubChem