Lifespan: The Revolutionary Science of Why We Age—and Why We Don't Have To

by David A. Sinclair

Nicotinamide riboside, or NR, is converted to NMN, so some people take NR instead of NMN because it is cheaper. Cheaper still are niacin and nicotinamide, but they don’t seem to raise NAD levels as NMN and NR do.

NR or NMN.