NMN has been showing up in a lot of health promotions and studies in the last few years. People say that it "mitigates age-associated physiological decline in mice" (Mills 2016)

Have scientists done studies comparing NMN and VitB3?

The reason I ask pertains to the fact that they are both part of the Kegg Pathway in Biochemistry. There would little reason in supplementing with NMN for people without deficiencies in their Kegg Pathway enzymes, unless there are biochemical pathways that maintain mitochondrial integrity that aren't being discussed in a general biochemistry course.

NMN is a precursor to NAD for Oxid/Phosphorylation efficiency, but there are many NAD precursors. What makes NMN or NR most beneficial if they really are? And much more beneficial are they? There should be quantitative data related to this somewhere...