Which is why NA has been documented as an effective NAD+ precursor for ages. You must really dislike that flush? Let's keep this on topic guys!
No my wife will not take 500mg of niacin or any dosage in-between and she's not alone, I have no such aversion and back in my 20s I enjoyed the flush. Now I take a deliberate approach and use inversion as a vasotonic to reach all the tissues spaces of my body and increase Vaso-Muscular tone.
I've seen that paper and Dr. Charles Brenner was involved and is currently the researcher involved in the new PK study just commencing. Let me tell you guys I don't mess around and have forwarded our questions directly to the source asking for the "long" explanation. Who knows we may influence the questions in this new study. They may or may not answer us, in fact I've already received a statement that falls short of directly answering our questions but I'm told a definitive answer will be forthcoming within the next 12 months. And I know this isn't helpful for those on the fence.
So what can I tell you, if you ask an (NR) researcher "today" the best approach to raising NAD levels, they are going to say; "Nicotinamide Riboside!"
Are there alternative paths, yes. Which NAD precursor will give you the highest possible NAD levels within the cytoplasm of the cell. This is the true question. Researchers have already established NAD levels did not raise equally in all tissue samples across the different NAD precursors. So far I'm hitting a unified front indicating (NR) is the precursor of choice for all tissues.
Oh . . . I did get an unquotable response to the "Is (NR) broken down into nicotinamide (NAM) before it's absorbed?
And I've been told;
"NR does not digest or metabolize into NAM"
& "NR is superior in every way."
So from a group of researchers who all have some skin in the game "Nicotinamide Riboside" is heralded as the NAD solution.
And I will quote someone when they agree to go on the record. Until then I will respect privacy until that person is willing to have their name mentioned.