什么是胆固醇

存在血浆和所有动物组织内的一种蜡状物质。是一种类固醇，分子式为C2746。胆固醇为生命所必需，它是细胞膜的重要组成，为体内合成胆酸、类固醇激素和维他命D的原料或中间产物。胆固醇并不溶於血，故须附於某些蛋白质复合体（称为脂蛋白）上，方能於血液中运输。它是由肝脏和其他一些器官制造，以饮食摄取量的多寡来调节。血中胆固醇过高会沈积在血管内壁上（参阅arteriosclerosis），导致冠状动脉心脏病。1985年布朗（M. Brown, 1941～）和戈德斯坦（Joseph Goldstein, 1940～）因发现这个过程而共获诺贝尔医学或生理学奖。避免血胆固醇过高的最佳对策为降低饮食中的胆固醇摄取量以及减少动物性脂肪（如饱和或过饱和脂肪）的摄取量。参阅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.