NMNRx a powerful support for healthy aging and vitality NMN (nicotinamide mononucleotide) is a powerful, metabolically active form of vitamin B3. It is naturally found in fruits and vegetables, although most NMN is synthesized by the body from nicotinamide, a form of vitamin B3 found in food. NMN is a promising molecule for rejuvenation of cellular health and for prevention of age-related diseases. In our cells, NMN can easily be synthesized into the potent and essential molecule NAD+ (nicotinamide adenine dinucleotide).