什麼是膽固醇

存在血漿和所有動物組織內的一種蠟狀物質。是一種類固醇，分子式為C2746。膽固醇為生命所必需，它是細胞膜的重要組成，為體內合成膽酸、類固醇激素和維他命D的原料或中間產物。膽固醇並不溶於血，故須附於某些蛋白質複合體（稱為脂蛋白）上，方能於血液中運輸。它是由肝臟和其他一些器官制造，以飲食攝取量的多寡來調節。血中膽固醇過高會沈積在血管內壁上（參閲arteriosclerosis），導致冠狀動脈心臟病。1985年布朗（M. Brown, 1941～）和戈德斯坦（Joseph Goldstein, 1940～）因發現這個過程而共獲諾貝爾醫學或生理學獎。避免血膽固醇過高的最佳對策為降低飲食中的膽固醇攝取量以及減少動物性脂肪（如飽和或過飽和脂肪）的攝取量。參閲triglyceride。

cholesterol

Waxy organic compound found in blood and all animal tissues. It is a steroid, with molecular formula C27H46O, containing four rings in its structure. Cholesterol is essential to life; it is a primary component of cell membranes and a starting or intermediate material from which the body makes bile acids, other steroid hormones, and vitamin D. It is made in the liver and some other organs, in greater or lesser amounts depending on the amount recently consumed in the diet. It circulates in the blood in compounds called lipoproteins, since it is not water-soluble alone. Excess cholesterol in the blood forms deposits in arteries (see arteriosclerosis), which can lead to coronary heart disease. Michael Brown (born 1941) and Joseph Goldstein (born 1940) won a Nobel Prize in 1985 for their work in discovering this process. Since the body makes cholesterol from fats, blood cholesterol cannot be reduced by limiting only the amount of cholesterol in the diet; the amount of fat, especially saturated fat (see saturation, fatty acid) must also be reduced. See also triglyceride.