Hathcock John N, Shao Andrew
Council for Responsible Nutrition, 1828 L St., NW, Suite 900, Washington, DC 20036-5114, USA.
Regul Toxicol Pharmacol. 2006 Oct;46(1):23-8. doi: 10.1016/j.yrtph.2006.06.007. Epub 2006 Aug 9.
Carnitine is a conditionally essential amino acid-like compound involved in the transport of long-chain fatty acids into the mitochondria during the beta-oxidation process. Carnitine has become an increasingly popular ingredient in dietary supplements, especially weight loss and some sports nutrition products. A number of clinical trials have been conducted examining the effect of carnitine supplementation on weight loss and energy balance. Regarding safety, systematic evaluation of the research designs and data do not provide a basis for risk assessment and the usual safe upper level of intake (UL) derived from it unless the newer methods described as the observed safe level (OSL) or highest observed intake (HOI) are utilized. The OSL risk assessment method indicates that the evidence of safety is strong at intakes up to 2000mg/day l-carnitine equivalents for chronic supplementation, and this level is identified as the OSL. Although much higher levels have been tested without adverse effects and may be safe, the data for intakes above 2000mg/day are not sufficient for a confident conclusion of long-term safety.
肉碱是一种类似条件必需氨基酸的化合物，在β-氧化过程中参与长链脂肪酸向线粒体的转运。肉碱在膳食补充剂中越来越受欢迎，尤其是在减肥和一些运动营养产品中。已经进行了多项临床试验，研究补充肉碱对减肥和能量平衡的影响。关于安全性，除非采用称为观察到的安全水平（OSL）或最高观察摄入量（HOI）的新方法，否则对研究设计和数据的系统评估无法为风险评估及其得出的通常安全摄入量上限（UL）提供依据。OSL风险评估方法表明，长期补充左旋肉碱当量每日摄入量达2000毫克时，安全性证据充分，这一水平被确定为OSL。尽管已经测试了更高的剂量且无不良反应，可能是安全的，但每日摄入量超过2000毫克的数据不足以得出关于长期安全性的确切结论。
