If you are old enough to remember the hype about resveratrol and sirtuins, that eventually resolved to nothing at all of any great use for human medicine, this

If you are old enough to remember the hype about resveratrol and sirtuins, that eventually resolved to nothing at all of any great use for human medicine, this is basically the same people singing the same song about roughly the same area of biochemistry. On the face of past events, they can't really be trusted to tell you how great it is and how promising it is, so just read the facts and compare with other studies. About the most one can say about this is that manipulation of NAD+ levels is a better exercise mimetic than manipulation of sirtuins proved to be. What it helps to do is explain some of the underpinnings of studies that show a great deal of muscle loss is secondary aging - i.e. disuse. It also suggests that loss of capillaries is a more important mechanism in sarcopenia than other groups believe to be the case, though I think it very possible that this is secondary to stem cell activity loss. The evidence for stem cell decline to be the primary cause of sarcopenia is very good. [1] There is a faction that thinks capillary loss is important in all tissues. [2] Go look at the studies showing resistance training to be pretty effective in seniors before getting excited about NAD+ boosters. The resistance training is probably cheaper and better. One still has studies such as the one showing that dietary nicotinamide doesn't do a great deal in mice [3] - like sirtuin manipulations, it helps fat mice a little, but is distinctly unimpressive otherwise. Remember that calorie restriction extends life by 40% in mice, but probably five years or less in humans - the effects of all these stress response related mechanisms of metabolic manipulation work through a few overlapping core processes, and scale down with species longevity. That's why I see them as a dead end in comparison to other strategies. [1]: https://www.urmc.rochester.edu/news/story/4788/stem-cells-may-be-the-key-to-staying-strong-in-old-age.aspx https://www.urmc.rochester.edu/news/story/4788/stem-cells-ma... [2]: https://doi.org/10.1159/000477402 https://doi.org/10.1159/000477402 [3]: https://doi.org/10.1016/j.cmet.2018.02.001 https://doi.org/10.1016/j.cmet.2018.02.001