所有高等动物的主要固醇 the principal sterol of all higher animals, 分布在身体组织中 distributed in body tissues, 特别是大脑和脊髓 especially the brain and spinal cord, 以及动物油脂中。构成。游离或酯 and in animal fats and oils. Constit. either free or as esters, 鱼肝油 of fish liver oils, lard, 乳脂 dairy fats, 蛋黄和麸皮 egg yolk and bran 每天约20-25％的胆固醇产生于肝脏；高合成率的其他部位包括肠道 About 20?25% of total daily cholesterol production occurs in the liver; other sites of high synthesis rates include the intestines, 肾上腺和 器官。体内的合成始于一分子乙酰可可脂和一分子乙酰乙酰可可脂 adrenal glands and reproductive organs. Synthesis within the body starts with one molecule of acetyl CoA and one molecule of acetoacetyl-CoA, 甲基紫罗兰酮是用于香料的最通用的材料之一。尽管它以多种不同的异构体形式出现-当今最广泛使用的质量是伽马（异-α）形式或占主导地位的异构体混合物。有异味，介于花香之间 which are dehydrated to form 3-hydroxy-3-methylglutaryl CoA (HMG-CoA). This molecule is then reduced to mevalonate by the enzyme HMG-CoA reductase. This step is an irreversible step in cholesterol synthesis and is the site of action for the statins (HMG-CoA Reductase Inhibitors).; Cholesterol is a lipidic, 蜡状类固醇存在于细胞膜中，并在所有动物的血浆中运输。它是哺乳动物细胞膜的重要组成部分，需要建立适当的膜渗透性和流动性。此外 waxy steroid found in the cell membranes and transported in the blood plasma of all animals. It is an essential component of mammalian cell membranes where it is required to establish proper membrane permeability and fluidity. In addition, 胆固醇是 酸生物合成的重要前体分子 cholesterol is an important precursor molecule for the biosynthesis of bile acids, 类固醇激素 steroid hormones, 和几种脂溶性维生素。胆固醇是动物合成的主要固醇 and several fat soluble vitamins. Cholesterol is the principal sterol synthesized by animals, 但其他真核生物中少量合成 but small quantities are synthesized in other eukaryotes, 例如植物和真菌。在原核生物中几乎完全没有 such as plants and fungi. It is almost completely absent among prokaryotes, 其中包括细菌。胆固醇是一种固醇（类固醇和醇的混合物）和在所有 体组织的细胞膜中发现的脂质 which include bacteria.; Cholesterol is a sterol (a combination steroid and alcohol) and a lipid found in the cell membranes of all body tissues, 并在所有动物的血浆中运输。这个名字起源于希腊的胆（ ）和立体声（固体） and transported in the blood plasma of all animals. The name originates from the Greek chole- (bile) and stereos (solid), 和化学后缀-ol -ol表示醇 , as 研究 员 研究 researchers 第一 first identified cholesterol (C27H45OH) in 固体 solid form in 胆结石 gallstones in 1784. Cholesterol is 运输 运输 transported 始终 通过 throughout the body via 脂蛋白 lipoprotein 粒子 粒子 particles. The 最大的 大 largest 脂蛋白 脂蛋白 lipoproteins, 主要将脂肪从肠粘膜转运到肝脏 which primarily transport fats from the intestinal mucosa to the liver, 评估控制措施以实现在食用新鲜切碎的卷心莴苣时达到每克小于100 cfu单核细胞增生李斯特氏菌的食品安全目标。 are called chylomicrons. They carry mostly triglyceride fats and cholesterol (that are from food and especially internal cholesterol secreted by the liver into the bile). In the liver, 乳糜微粒会释放甘油三酸酯和一些chylomicron particles give up triglycerides and some cholesterol, 并转化为低密度脂蛋白（ldl）颗粒 and are converted into low-density lipoprotein (LDL) particles, 将甘油三酸酯和胆固醇带到其他 体细胞。在健康个体中，ldl颗粒较大且数量相对较少。相反 which carry triglycerides and cholesterol on to other body cells. In healthy individuals the LDL particles are large and relatively few in number. In contrast, 大 large 数字 数 numbers of small 低密度脂蛋白 LDL 粒子 粒子 particles are 强烈地 strongly 关联的 associated with 促进 promoting 动脉粥样化的 动脉粥样硬化 atheromatous 疾病 disease 中 within the 动脉 arteries. (缺乏 Lack of information on 低密度脂蛋白 LDL 粒子 particle 数 number and size is one of the major 问题 problems of 常规 conventional lipid 测试 tests.). In 条件 健康）状况 conditions with 高架 elevated 浓度 浓度 concentrations of oxidized 低密度脂蛋白 LDL 粒子 粒子 particles, 特别是小ldl颗粒 especially small LDL particles, 胆固醇促进动脉粥样硬化斑块沉积 cholesterol promotes atheroma plaque deposits in the walls of arteries, 一种称为动脉粥样硬化的疾病 a condition known as atherosclerosis, 这是导致冠心病和其他形式的心血管疾病的主要因素。 （相反 which is a major contributor to coronary heart disease and other forms of cardiovascular disease. (In contrast, hdl颗粒是从动脉粥样硬化中清除胆固醇的唯一确定机制。大型高密度脂蛋白 HDL颗粒浓度增加 , 不是总的高密度脂蛋白 HDL粒子 , 与较低的动脉粥样硬化进展相关 correlate with lower rates of atheroma progressions, 甚至回归。）。世界范围内都有一种趋势认为总胆固醇水平降低与动脉粥样硬化事件发生率降低相关（尽管许多研究都驳斥了这一想法）。由于这个原因 even regression.). There is a world-wide trend to believe that lower total cholesterol levels tend to correlate with lower atherosclerosis event rates (though many studies refute this idea). Due to this reason, 胆固醇已成为科学研究者的一大重点，他们试图确定健康饮食中所需的胆固醇含量。然而 cholesterol has become a very large focus for scientific researchers trying to determine the proper amount of cholesterol needed in a healthy diet. However, 动脉粥样硬化与胆固醇的主要联系一直是胆固醇转运模式 the primary association of atherosclerosis with cholesterol has always been specifically with cholesterol transport patterns, 不是总胆固醇本身。例如 not total cholesterol per se. For example, 总胆固醇可能很低 total cholesterol can be low, 但是主要由小ldl和小hdl颗粒组成，动脉粥样硬化的增长率很高。相反 yet made up primarily of small LDL and small HDL particles and atheroma growth rates are high. In contrast, 然而 however, 如果ldl粒子数少（大多数是大粒子），而hdl粒子的很大一部分很大（hdl主动逆向转运胆固醇） if LDL particle number is low (mostly large particles) and a large percentage of the HDL particles are large (HDL is actively reverse transporting cholesterol), 那么动脉粥样硬化的增长率通常很低 then atheroma growth rates are usually low, 甚至消极 even negative, 对于任何给定的总胆固醇浓度。内皮中不对称二甲基精氨酸（adma）的相对浓度使这些作用更加复合物 for any given total cholesterol concentration. These effects are further complicated by the relative concentration of asymmetric dimethylarginin (ADMA) in the endothelium, 因为adma会下调一氧化氮的产生 since ADMA down-regulates production of nitric oxide, 内皮的松弛剂。从而 a relaxant of the endothelium. Thus, 高水平的阿德玛 high levels of ADMA, 紫草叶提取物婆罗门叶提取物m叶提取物紫罗兰叶提取物小叶紫苏叶提取物紫苏叶的提取物。 associated with high oxidized levels of LDL pose a heightened risk factor for vascular disease. -- Wikipedia; Given the well-recognized role of cholesterol in cardiovascular disease, masoprocol是一种新型抗肿瘤药。尚不清楚马索普洛尔是如何工作的。实验室实验表明，马索普洛尔可以阻止类似于光化性角化酶中发现的细胞的增殖。 masoprocol从美国撤出。 1996年6月上市。 it is surprising that some studies have shown an inverse correlation between cholesterol levels and mortality in subjects over 50 years of age?an 11% increase overall and 14% increase in CVD mortality per 1 mg/dL per year drop in cholesterol levels. In the Framingham Heart Study, 研究 员将此现象归因于患有严重慢性疾病或癌症的 的胆固醇水平往往低于正常水平。福拉尔贝格州健康监测和促进计划不支持此解释 the researchers attributed this phenomenon to the fact that people with severe chronic diseases or cancer tend to have below-normal cholesterol levels. This explanation is not supported by the Vorarlberg Health Monitoring and Promotion Programme, 其中所有年龄段的男性和50岁以上胆固醇极低的女性越来越可能死于癌症 in which men of all ages and women over 50 with very low cholesterol were increasingly likely to die of cancer, 肝病 liver diseases, 和精神疾病。该结果表明，即使在年轻的受访者中，胆固醇含量也较低 and mental diseases. This result indicates that the low cholesterol effect occurs even among younger respondents, 呋喃-2-基辛酸甲酯2-呋喃基辛酸甲酯2-呋喃基甲基辛酸酯糠酸癸酯α-糠基辛酸2-糠酸辛酯 contradicting the previous assessment among cohorts of older people that this is a proxy or marker for frailty occurring with age.; Mevalonate is then converted to 3-isopentenyl pyrophosphate in three reactions which require ATP. This molecule is decarboxylated to isopentenyl pyrophosphate, 1-甲氧基-2-甲基-邻甲苯基甲基醚邻甲苯基甲基醚1-甲氧基-2-甲基苯1-甲氧基-2-甲基苯2-甲氧基甲苯基-甲氧基甲苯甲苯基-甲氧基甲苯甲基2-甲基苯基醚2-甲基苯甲醚-甲基苯甲醚2-甲基苯甲醚天然2-甲基甲氧基苯甲基邻甲苯基醚甲基邻甲酚醚2-甲基邻甲苯基醚2-甲基茴香醚-甲基茴香醚或邻甲基茴香醚 which is a key metabolite for various biological reactions. Three molecules of isopentenyl pyrophosphate condense to form farnesyl pyrophosphate through the action of geranyl transferase. Two molecules of farnesyl pyrophosphate then condense to form squalene by the action of squalene synthase in the endoplasmic reticulum. Oxidosqualene cyclase then cyclizes squalene to form lanosterol. Finally, 羊毛甾醇然后转化为胆固醇。细胞内 lanosterol is then converted to cholesterol.; Within cells, 胆固醇是几种生化途径中的前体分子。在肝脏 cholesterol is the precursor molecule in several biochemical pathways. In the liver, 胆固醇转化为 cholesterol is converted to bile, 然后将其储存在胆囊中。 中含有胆盐 which is then stored in the gallbladder. Bile contains bile salts, 可以溶解消化道中的脂肪，并帮助肠道吸收脂肪分子以及脂溶性维生素 which solubilize fats in the digestive tract and aid in the intestinal absorption of fat molecules as well as the fat soluble vitamins, 维生素A Vitamin A, 维生素D Vitamin D, 维生素E和维生素k K。胆固醇是维生素D和类固醇激素合成的重要前体分子 , 包括肾上腺激素皮质醇和醛固酮以及性激素黄体酮 including the adrenal gland hormones cortisol and aldosterone as well as the sex hormones progesterone, 雌激素 estrogens, 和睾丸激素及其衍生物。 and testosterone and their derivatives.