NMN

What it is

NMN (nicotinamide mononucleotide) is a molecule the body uses as a direct precursor to NAD+, the essential coenzyme involved in energy metabolism and cellular repair. Because NAD+ levels appear to decline with age, NMN became one of the most popular "longevity" supplement ingredients as a way to try to raise NAD+.

What it does

• Reliably raises blood NAD+. This is the well-supported, repeatable finding across human trials — NMN supplementation increases circulating NAD+.
• Shows early, modest functional signals. Some trials report improvements in things like walking performance or muscle insulin sensitivity, often in specific populations.

What it does NOT do

• It is not proven to "reverse aging." Whether raising NAD+ produces meaningful health or longevity benefits in people is still unsettled, with mixed and modest human results.
• Bigger isn't clearly better. In at least one trial, benefits peaked around a mid-range dose rather than the highest.
• Its dramatic reputation is largely from mice. Rodent results have not fully translated to humans.

Forms and doses

• Sold as capsules, tablets, or powder (usually beta-NMN).
• Studied at roughly 250–1,200 mg/day (some short-term use up to 2,000 mg); well tolerated up to ~900 mg/day over weeks to months, though long-term safety data are lacking.
• Regulatory note: the US status of NMN as a dietary supplement is contested — the FDA has taken the position that NMN is excluded from the supplement definition, and its status has been disputed. Availability may vary by market and over time.

Sources

1. Yoshino M, et al. NMN increases muscle insulin sensitivity in prediabetic women. Science, 2021.
2. Song Q, et al. The safety and antiaging effects of NMN in human clinical trials: an update. 2023.