NMN and NR are effective NAD precursors because they are smaller molecules that can be taken up into cells, with NR being smaller and better absorbed than NMN.

“Even in yeast if you give them NAD it doesn't work because it's too big, it doesn't get taken up into the cells.”

“obviously one of the most popular types of supplements being offered on the market today and there are several of them are supplements that are aimed at delivering precursors to nad production”

“a portion of the nicotine MN nicotine my mononucleotide a portion of that becomes NR and then gets comes back to n MN and I don't know exactly why but I think it's like a pressure release valve”

“nicotinamide mononucleotide i think may be able to enter cells directly or nicotinamide ribosides these are partially broken down forms of nad but that are nevertheless meaningfully closer to nad than the normal things that circulate in good amounts in our bloodstream and that does partially i would say short circuit the route to cells making nad so they kind of can break down partially the nad in the bloodstream take these partially broken down nad precursors into cells and rebuild nad in a shortcut manner that probably has a good chance to bolster nad levels”

“So NMN and NR are two molecules. So it stands for nicotinamide mononucleotide, which is essentially the precursor, the immediate precursor to NAD. If you'd give a cell NMN, it will be taken up by a transporter, which was just discovered by my buddy Shin Imai, we used to work together at MIT. Now he's at WashU. A few weeks ago, he wrote about it. I wrote about it, that there's a transporter that sucks up NMN, and the NMN is converted within one step to NAD in the cell, and now it's locked. It's a big molecule, it's locked inside the cell. And that step is carried out by an enzyme. It's got a name, it's called NAMPT.”