Although baseline requirements for nicotinamide adenine dinucleotide (NAD+) synthesis can be met either with dietary tryptophan or with less than 20 mg of daily niacin, which consists of nicotinic acid and/or nicotinamide, there is growing evidence that substantially greater rates of NAD+ synthesis may be beneficial to protect against neurological degeneration, Candida glabrata infection, and possibly to enhance reverse cholesterol transport. The distinct and tissue-specific biosynthetic and/or ligand activities of tryptophan, nicotinic acid, nicotinamide, and the newly identified NAD+ precursor, nicotinamide riboside, reviewed herein, are responsible for vitamin-specific effects and side effects. Because current data suggest that nicotinamide riboside may be the only vitamin precursor that supports neuronal NAD+ synthesis, we present prospects for human nicotinamide riboside supplementation and propose areas for future research.

中文翻译：

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烟酸，烟酰胺和烟酰胺核糖苷：人体营养中NAD +前体维生素的分子评估。

尽管日粮色氨酸或每日烟酸含量少于20 mg（由烟酸和/或烟酰胺组成）可以满足烟酰胺腺嘌呤二核苷酸（NAD +）合成的基线要求，但越来越多的证据表明，NAD +合成速率可能大大提高有助于预防神经变性，光滑念珠菌感染，并可能增强胆固醇逆向转运。色氨酸，烟酸，烟酰胺和新近鉴定的NAD +前体烟酰胺核糖苷的独特的和组织特异性的生物合成和/或配体活性，是维生素特异作用和副作用的原因。由于当前数据表明烟酰胺核糖可能是唯一支持神经元NAD +合成的维生素前体，