As a result of this paper, many believe there’s a transporter that carries NAD+ booster NMN (FAQs and Anecdotes) into cells. Dr. Charles Brenner, who discovered Nicotinamide Riboside “NR” (FAQs) (Anecdotes) as an NAD+ booster vitamin says the notion of the existence of a transporter is mistaken. Below, he makes the case:

DR. Brenner Makes His Case (Podcast):

“It’s not an NMN transporter.

I would be delighted if there were such a thing.

But there’s no evidence in that paper for the transport of NMN.

It gets into technical details.

But, if you basically have 100 micromolar of NMN, which is a high concentration on the outside of cells for an hour, and you don’t see an increase in NMN inside the cells other than in the one minute the first time point which they said they couldn’t properly mix and then when you look at the actual data the error bar on it and it’s just…

There are assays in that paper that simply don’t make sense with a very simple phrase in science and technology and engineering called “garbage in and garbage out”.

So, if you have poor analytical assays and you can’t measure something and you can’t do those time points and you don’t have the methods to detect something, then you can’t say that you detected it.

And the fact of the matter is that the molecule that was reported to be an NMN transporter is in a family of enzymes that transports sodium and potassium.

Sodium and Potassium have no resemblance to any nucleoside or nucleotide. It’s not the class of proteins that would transport a nucleoside or nucleotide.

It would be profoundly amazing if it were true.

But there’s no evidence that it is true.

And, in fact, when you do the experiment which we and many other groups have done where you have NMN on the outside of cells, and you use valid analytical methods that can separate NMN to NR, you see that NMN is converted quantitatively — that means fully — to NR outside of the cell.

Then NR goes into the cell, phosphate gets put on it, and now it’s NMN inside the cell and then it gets converted into NAD”

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