Modulating NAD+ metabolism, from bench to bedside.

Discovered in the beginning of the 20th century, nicotinamide adenine dinucleotide (NAD+) has evolved from a simple oxidoreductase cofactor to being an essential cosubstrate for a wide range of regulatory proteins that include the sirtuin family of NAD+-dependent protein deacylases, widely recognized regulators of metabolic function and longevity. Altered NAD+ metabolism is associated with aging and many pathological conditions, such as metabolic diseases and disorders of the muscular and neuronal systems. Conversely, increased NAD+ levels have shown to be beneficial in a broad spectrum of diseases. Here, we review the fundamental aspects of NAD+ biochemistry and metabolism and discuss how boosting NAD+ content can help ameliorate mitochondrial homeostasis and as such improve healthspan and lifespan.