Researchers at Harvard Medical School gave old mice a precursor the body uses to build NAD+, called NMN, and measured whether it could restore the blood vessel density and exercise capacity that normally decline with age.
In the peer-reviewed study, old mice given NMN showed restored capillary density in skeletal muscle and had better blood flow and more endurance on a treadmill than untreated old mice of the same age. The effect traced to a signaling pathway involving NAD+ and hydrogen sulfide inside the blood vessel lining.
NMN is a precursor molecule the body converts into NAD+, not NAD+ itself, a distinction that matters because the two are not automatically interchangeable in every tissue. Exercise or extra hydrogen sulfide strengthened the effect, and the result comes from mouse experiments, with human trials of NAD+ precursors still working out dosing and long-term safety.
Read the original study
Old vessels, rebuilt in old mice.
Source
- Das, A., Huang, G. X., Bonkowski, M. S., Longchamp, A., Li, C., Schultz, M. B., Kim, L.-J., Osborne, B., Joshi, S., Lu, Y., Treviño-Villarreal, J. H., Kang, M.-J., Hung, T.-T., Lee, B., Williams, E. O., Igarashi, M., Mitchell, J. R., Wu, L. E., Turner, N., . . . Sinclair, D. A. (2018). Impairment of an Endothelial NAD+-H2S Signaling Network Is a Reversible Cause of Vascular Aging. Cell, 173(1), 74–89.e20. https://doi.org/10.1016/j.cell.2018.02.008