Rebouche C J
Department of Pediatrics, University of Iowa, Iowa City 52242.
FASEB J. 1992 Dec;6(15):3379-86.
L-Carnitine has been described as a "conditionally essential" nutrient for humans. Segments of the human population suggested as having a requirement for carnitine include infants (premature and full-term), patients on long-term parenteral nutrition, and perhaps children. The evidence to support these claims includes 1) low circulating carnitine concentrations; 2) abnormal (or at least different) circulating metabolite concentrations (free fatty acids, triglycerides, ketone bodies), and 3) very limited and inconsistent growth data. A number of subjective observations and anecdotal case reports have been offered in support of a requirement for carnitine. Exogenous carnitine is required to maintain "normal" (in the epidemiologic sense) plasma or serum carnitine concentrations in humans of all ages. But "functional carnitine deficiency," defined by abnormal clinical presentation correctable by carnitine administration, has not been demonstrated in an otherwise normal (nonpathologic) population. On the other hand, nutritional or pharmacological intervention with carnitine or its esters may be beneficial for very premature infants, infants and children with various clinical conditions associated with low circulating carnitine concentrations, and in some chronic diseases associated with the aging process.
左旋肉碱被描述为人类的一种“条件必需”营养素。被认为需要肉碱的人群包括婴儿（早产儿和足月儿）、长期接受肠外营养的患者，可能还包括儿童。支持这些说法的证据包括：1）循环中肉碱浓度低；2）循环代谢物浓度异常（或至少不同）（游离脂肪酸、甘油三酯、酮体）；3）非常有限且不一致的生长数据。也有一些主观观察和轶事性病例报告支持对肉碱的需求。外源性肉碱是维持各年龄段人类“正常”（从流行病学意义上讲）血浆或血清肉碱浓度所必需的。但是，在其他方面正常（无病理状态）的人群中，尚未证实由肉碱给药可纠正的异常临床表现所定义的“功能性肉碱缺乏”。另一方面，用肉碱或其酯进行营养或药物干预可能对极早产儿、患有各种与循环中肉碱浓度低相关临床病症的婴儿和儿童以及一些与衰老过程相关的慢性疾病有益。
