It is true that convincing human clinical trial data for taking an NMN supplement or NR supplement is lacking. However, given their safety and probable upside potential, NMN and NR might be the perfect solution to extend your health span with a minimum investment.
Can I get NAD+ exclusively from food?
If you think that there are dietary alternatives, you might be disappointed. You cannot adequately boost NAD+ levels by consuming “nmn foods” and “nr foods” like milk. For example, you would need to drink 1,300 glasses of milk per day.
Did the 2022 NMN efficacy clinical trial fail due to suboptimal NMN dose?
David Sinclair, a Harvard faculty member and one of the leading scientists in the NMN community, takes a 1,000mg daily dose of NMN. In contrast, the first human clinical trial completed in 2022 that tested the efficacy of NMN only used a 300mg daily dose, which is probably a suboptimal dose. That might explain why that particular study did not show statistically significant benefits of NMN.
It could take a long time for us to find the “right” doses of NR or NMN in clinical trials. This is because extrapolating doses for humans from doses used in animals–which is also called allometric scaling of drug doses–has always been a challenging process in drug development.
How safe are NMN and NR supplements?
If NMN or NR is indeed a life-changing substance (as it is for the rats and yeasts in published papers in Nature, Science, and Cell), effectively shows that clinical trials could take at least 10-20 more years. At the same time, according to a clinical study on safety conducted in 2021 (J Int Soc Sports Nutr. 2021 Jul 8;18(1):54), “NMN doses up to 1200mg per day over a six-week time course are safe in humans.” Similarly, a clinical study conducted in 2017 (Dellinger et al, npj Aging and Mechanisms of Disease (2017)0:17) showed that NR 500mg daily for 8 weeks is safe.
It comes down to your own benefit-risk analysis
Some experts, such as David Sinclair, are taking a chance themselves by taking NMN on a daily basis while regularly monitoring their own blood tests to detect potential side effects. In fact, in his book Lifespan, Sinclair states “human studies with NAD boosters are ongoing. So far, there has been no toxicity, not even a hint of it.” Perhaps that is why NMN is at the top of David Sinclair’s supplements list.
Whether you take NMN or NR–which has shown to extend the lifespan and the health span of mice and yeast but not yet in humans–is your own decision to make after consulting with your physician. For some people, the upside potential of taking these semi-proven supplements is much greater than the probably minor downside risk. Knowing those clear outcomes of clinical trials might not be available for another 10-20 years, and knowing that taking these supplements is relatively safe, it might not be a bad idea to jump on board.