By Sean Green
Cholesterol is an essential part of life. It is produced by the liver which synthesises about 1 gramme per day. This substance is classified as a sterol (a combination of steroid and alcohol).
Cholesterol forms an essential component of cell membranes of mammals.It is the main precursor of vitamin D and of the steroid hormones such as cortisol and aldosterone and the sex hormones (oestrogens, testosterone and progesterone). It also is essential in the formation of the myelin sheath which wraps around nerves and helps to conduct nerve impulses.
An excessively high cholesterol, however is associated with atherosclerosis, which is essentially a narrowing and clogging up of arteries with a complex of cholesterol in a scaffolding of scar tissue. This narrowing of blood flow through arteries has the most significant effect in the heart (where it may cause heart attacks) and in the brain (where it is associated with strokes).
According to the lipid theory, raised levels of total cholesterol, as well as LDL cholesterol (commonly called bad cholesterol), as well as low levels of HDL cholesterol (commonly called |
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