NAD and its possible role in gut microbiota: Insights on the mechanisms by which gut microbes influence host metabolism.

Nicotinamide adenine dinucleotide (NAD) is an enzyme cofactor, co-substrate, and redox factor in all living cells and is necessary for maintaining cell metabolism. It has been shown that appropriate supplementation of NAD precursors or inhibition of NAD-depleting enzymes can promote mitochondrial oxidative phosphorylation and improve host energy utilization efficiency. In addition, increasing evidence indicates that the gut microbiota plays a pivotal role in host metabolism. Theoretically, there should be a close correlation among NAD, gut microbiota, and host metabolism; however, the information is limited. In this review, we summarize the metabolic process of NAD and its impact on host metabolism, the link between gut microbiota and host metabolism, as well as the potential effects of NAD on microbial metabolism, providing a new perspective on the interaction between gut microbiota and host metabolism.