[ck2]

Note I am not disputing NAD supplementation, only the limits of what it can do and who can benefit from it.

The key to NAD supplementation is the people who need it are older or ill.

There are a lot of other processes in such bodies that become deficient too.

None of the supplement methods for NAD, Niacin, NR, NMN will boost levels beyond what your body will use.

This is what the NAD cycle looks like, you can see NA (niacin) vs NR vs NMN are each closer to production but the end result is the same of what ends up in the blood vs organs like liver.

https://www.lifespan.io/wp-content/uploads/2019/06/NAD_schem...

There are wild arguments, even with scientific rigor, about NR vs NMN ability to get into cells. It is more likely that genetics matters and it varies from person to person and what else is in their diet.