NAD+ is a bulky molecule that is not absorbed orally and needs to be given intravenously. Intravenous administration can be inconvenient and costly. On the other hand, two key NAD+ precursors (see Figure 7), NMN (Nicotinamide Mononucleotide) and NR (Nicotinmaide Riboside), are smaller and cheaper than NAD+, and can be taken orally. Unlike NAD+ whose scientific data in the context of longevity is lacking, NMN and NR have been extensively…