Why Don't NAD+ Levels Increase Significantly in Humans?

[LightningInAJar]

TL;DR Summary

Can NAD+ conversion in humans be increased?

As I understand it only in mice do precursors like nmn and nr readily get turned into NAD+ in the cells. But not so much in humans? What keeps NAD+ levels from increasing in people in any meaningful way?

 

[atyy]

I googled and found:

https://www.semanticscholar.org/paper/NAD+-homeostasis-in-health-and-disease.-Katsyuba-Romani/9970f02833257350da64318d54e075c203701c69
NAD+ homeostasis in health and disease
Elena Katsyuba, Mario Romani, Dina Hofer and Johan Auwerx
Nature metabolism 2:9–31 (2020)
"In preclinical settings, various strategies to increase NAD+ levels have shown beneficial effects, thus starting a competitive race to discover marketable NAD+ boosters to improve healthspan and lifespan. Here, we review the basics of NAD+ biochemistry and metabolism, and its roles in health and disease, and we discuss current challenges and the future translational potential of NAD+ research."