Key Points:
- Dr. Brenner says NR is a more effective than NMN because there are more human studies on NR, but more human studies on a given supplement does not necessarily mean that supplement is more effective.
- Brenner believes NMN does not come from a safe source, however, he provides no evidence for this.
- The anti-aging scientist points out that NMN is converted to NR before entering cells, but this does not mean that NR is more effective.
Charles Brenner, Ph.D. is a biochemist who studies NAD+ metabolism and the NAD+ precursor nicotinamide riboside (NR). He is Chief Scientific Advisor to ChromaDex, a company that sells NR through the brand TRU NIAGEN.
On September 4th, Brenner participated in an “ask me anything” (AMA) on Reddit, where members of the forum asked him questions pertaining to NAD+, NAD+ precursors, and aging. One Redditor called ItsMeBytes asked,
“Hi Dr Brenner. Thanks for this. From what I understand NMN and NR are equally effective. Is there a solid argument for one or the other?”
Brenner replied,
“there’s much less human research with NMN
there’s not a known safe source for NMN
NMN doesn’t get into cells as NMN. it gets in as NR and there’s a safe source of NR so why are we still talking about NMN?”
ItsMeBytes followed up with,
“More research is coming out though, no? I’m currently taking both NR and NMN. Can you expand on what you mean by no known safe source? The tests show my supps as pure NR and pure Nmn. Bryan Johnson took both and says they’re equally effective for raising nad.”
Seemingly dodging the question, Brenner answered,
“the F in FDA stands for food and it governs both food [and] new dietary ingredients
the DSHEA law states that if a substance has entered testing as a drug, it cannot be permitted as a dietary ingredient. Metro Biotech notified FDA that they have been testing NMN as a drug. FDA then told everyone that it cannot be a dietary ingredient
if you are buying NMN as a dietary ingredient, you are dealing with a company that is selling it in the face of a ruling by the US agency trying to keep dietary ingredients safe”
Are Brenner’s Points Valid?
A Higher Number of Human Studies Does Not Imply Effectiveness
One of Brenner’s arguments for NR being more effective than NMN is that “there’s much less human research with NMN.” This argument is built on the false premise that more human studies on a given compound make that compound more effective. This is not true, as demonstrated by a few human NR studies showing negative results.
For example, while NR supplementation increased the activation of proteins associated with NAD+ metabolism in muscle, it did not increase muscle NAD+ levels in older individuals. Another study showed that NR supplementation did not improve the metabolic response to exercise in male subjects. Additionally, in obese middle-aged men, NR supplementation did not improve insulin sensitivity.
Problems also arise with ItsMeBytes’ question, specifically by what is meant by “effective.” If this means more effective at promoting health and slowing aging, then there are more NMN human studies showing positive results for age-associated measures than NR. In any case, Brenner’s point needs elaboration for it to have any validity.
Raising Intracellular NAD+ Levels is What Matters
Another point Brenner makes is that “NMN doesn’t get into cells as NMN. it gets in as NR.” Since an NMN transporter called Slc12a8 that allows NMN to get into cells was recently discovered, it is difficult to grasp Brenner’s point without more elaboration. Even if the Slc12a8 transporter didn’t exist, whether or not NMN directly gets into cells does not determine its effectiveness.
Indeed, before the Slc12a8 transporter was discovered, the only known means of NMN getting into cells was for it to be first converted into NR. However, either way, NMN still gets into cells and is converted into NAD+. Hence, despite differing transport mechanisms, both NR and NMN raise intracellular NAD+ levels. Therefore, Brenner’s argument is based on the false premise that the route of entry for NAD+ precursors determines its effectiveness.
Most NMN and NR Supplments are Pure
It’s unclear what Brenner means by, “there’s not a known safe source for NMN.” The Redditor points out that his supplements are pure, which is the case for most NMN and NR supplements. Since there is no evidence of NMN coming from an unsafe source, Brenner is essentially spreading misinformation by making statements like this.
FDA Concerns
Brenner is right when he says, “the F in FDA stands for food.” Indeed, like Brenner says, the FDA has reversed its decision to acknowledge NMN as a new dietary ingredient (NDI). This is because Metro Biotech made the FDA realize they were investigating NMN as a new drug. But again, this does not mean that NMN is less effective than NR.
The Bottom Line
Whether NR is more effective than NMN remains inconclusive, largely due to a lack of human studies directly comparing the effects of NR to NMN. The closest we have is a study comparing NMN- and NR-containing formulations, which concluded that NMN and NR had similar effects. From this it seems that NMN and NR could be equally effective in countering aging.
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