She asks: “When comparing niacinamide to Nicotinamide Mononucleotide (NMN), it seems NMN is what we take as a supplement. Can both be taken safely?” What can we tell her?

Both of these substances can be taken orally with safety. When such materials are applied topically, that is simply a strategy for drug delivery that favors getting high tissue concentrations locally of an active material without the need for very high doses that would expose the entire body, potentially, to quite high amounts when taken orally, as that oral dose spreads through a much larger mass of tissue, as well as being subjected to active degradation through metabolism, especially by the liver, so we see no problem with the recommended formula as is.