Does NR cause the same NAM accumulation as NMN is converted to NR in the body?
Some NMN clearly does utilize the SLC12A8 transporter to enter cells, so does not have to be converted to NR. That is a myth that Dr Brenner can’t let go of.
That research also shows the CD73 enzyme that resides on the cell membrane does convert some NAD and NMN to NR, for another pathway into the cells. That NMN is not prone to further conversion to NAM, as it is at the cell membrane already.
The research also shows both SLC12A8 and CD73 is upregulated when NAD+ is low, and turned off when NAD+ is high, as cells open multiple pathways to bring in more NAD and precursors.
Lastly, this research shows when taken orally and not protected, much NMN is actually metabolized to NaMN, and takes a totally different pathway to NAD, so will not result in NAM (until after it becomes NAD and is recycled).