henry copeland:

Vitamin stops the aging process of organs: Nicotinamide riboside rejuvenates stem cells, allowing better regeneration processes in aged mice -- ScienceDaily

This is why the researchers wanted to "revitalize" stem cells in the muscles of elderly mice. And they did so by precisely targeting the molecules that help the mitochondria to function properly. "We gave nicotinamide riboside to 2-year-old mice, which is an advanced age for them," said the researcher. "This substance, which is close to vitamin B3, is a precursor of NAD+, a molecule that plays a key role in mitochondrial activity. And our results are extremely promising: muscular regeneration is much better in mice that received NR, and they lived longer than the mice that didn't get it."
- www.sciencedaily.com