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.