Can nucleotides lower your biological age?
NAD+ supplements measurably raise NAD+ levels in your blood and, in one study, prevented biological age from rising, but did not actively lower it. The evidence is still too thin for firm conclusions, but 600-900 mg of NMN per day appears safe and also improved walking ability in that same study.
NAD+ is a substance found in every cell of the body and plays a central role in energy production, DNA repair and keeping inflammation in check. As we age, NAD+ levels fall, and this appears to affect all the known processes of ageing. Taking NAD+ building blocks such as NMN or NR measurably raises NAD+ levels in the blood and in cells. That biological effect has been found consistently across several studies in people.
Whether that rise also lowers your biological age is a different matter. In one study with eighty participants, the biological blood age in the group taking a dummy pill rose after 60 days, while it stayed the same in the groups taking NMN. NMN may therefore have prevented the rise, but it did not actively lower biological age. That same study did find a clear improvement in walking ability: people taking 600 or 900 mg per day walked notably further on a six-minute walk test than those taking the dummy pill. This is, for now, one study lasting two months, but it is an encouraging signal.
For other measurable health outcomes, such as metabolism and energy levels, results in people are mixed. Some measures improve, others do not. The impressive findings from animal studies, where substances that raise NAD+ consistently improved lifespan and muscle function, have so far translated only partially to people.
Up to 900 mg of NMN per day appears safe and well tolerated; no notable side effects occurred in the available studies. Whether it is safe to take over many years has not yet been established. NAD+ infusions given through a vein, popular in wellness clinics, have not been studied at all in people for either effectiveness or safety: no studies in people have been done on this. An interesting newcomer is trigonelline, a substance also found in coffee that may help the body make more NAD+. In animal and cell studies it improved muscle strength and how well the cell's energy-producing units worked, but studies in people do not yet exist.
This answer draws on several review articles and one study in people with a dummy-pill comparison group (80 participants, 60 days, NMN 300-900 mg per day). The fact that NAD+ supplements raise NAD+ levels is well supported. The effects on biological age and other health outcomes in people rest on much weaker evidence: one short study with a limited number of participants and a computer-calculated age measure. The researchers behind the overview article themselves stressed that the available studies in people are small and short, and that larger and longer studies are needed. Animal studies are consistently positive but do not automatically translate to people.