Bach A C
Z Ernahrungswiss. 1982 Dec;21(4):257-65. doi: 10.1007/BF02020743.
The oxidation of long-chain fatty acids is carnitine-dependent. Indeed, only when they are bound to carnitine, in the form of acyl-carnitines, do fatty acids penetrate into the mitochondria to be oxidized. To meet the need for carnitine, animals depend on both endogenous synthesis and an exogenous supply. A diet rich in meat supplies a lot of carnitine, while vegetables, fruits, and grains furnish relatively little. Although it has a low molecular weight and acts at low doses in a vital metabolic pathway, carnitine should not be considered a vitamin, but rather a nutritive substance. Indeed, it seems that the diet of the adult human need not necessarily furnish carnitine: the healthy organism, given a balanced nutrition (sufficiently rich in lysine and methionine), may well be able to meet all its needs. Furthermore, it seems that a reduction of the exogenous supply of carnitine results in a lowering of its elimination in the urine. However, dietary carnitine is more important during the neonatal period. The transition from fetal to extrauterine life is accompanied by an increased role of lipids in meeting energy needs. This change is accompanied by a rise in the body of the levels of carnitine, which is mainly supplied in the maternal milk. Finally, this review briefly surveys the illnesses in which a dietary carnitine supplement proves useful.
长链脂肪酸的氧化依赖于肉碱。实际上，只有当脂肪酸以酰基肉碱的形式与肉碱结合时，它们才能穿透线粒体进行氧化。为了满足对肉碱的需求，动物既依赖内源性合成，也依赖外源性供应。富含肉类的饮食能提供大量肉碱，而蔬菜、水果和谷物提供的肉碱相对较少。尽管肉碱分子量低且在重要代谢途径中低剂量起作用，但它不应被视为维生素，而应被视为一种营养物质。事实上，成年人的饮食不一定需要提供肉碱：健康的机体在摄入均衡营养（富含赖氨酸和蛋氨酸）的情况下，很可能能够满足其所有需求。此外，似乎肉碱外源性供应的减少会导致其在尿液中的排泄量降低。然而，在新生儿期，膳食肉碱更为重要。从胎儿期到宫外生活的转变伴随着脂质在满足能量需求方面的作用增加。这种变化伴随着体内肉碱水平的升高，而肉碱主要由母乳提供。最后，本综述简要概述了膳食补充肉碱被证明有用的疾病。
