Short answer
An NAD supplement such as NR or NMN raises NAD-related markers in blood, but whether that improves health is unproven. A 2026 review of 33 human studies found the marker rise was consistent, while effects on health outcomes were mixed and often null. In NIH-funded mouse tests, NR did not extend life span. FDA ruled in September 2025 that NMN is not barred from supplements.
What the human trials measured
Most trials measure NAD levels, not health. In a 2018 trial in Nature Communications, 30 healthy middle-aged and older adults took nicotinamide riboside (NR) or placebo for 6 weeks each. NR was well tolerated and stimulated NAD metabolism. Blood pressure and artery stiffness were flagged only as ideas for larger trials.
A 2021 trial in Science gave nicotinamide mononucleotide (NMN) or placebo for 10 weeks to postmenopausal women with prediabetes and overweight or obesity. Muscle insulin sensitivity improved on NMN. That is one group of women and one measure, not proof of slower aging.
What reviews of all the trials show
A 2026 systematic review in Ageing Research Reviews found 33 human studies, 28 of them randomized. Oral NR and NMN consistently raised NAD-related markers and were generally well tolerated over weeks to months. Effects on function, metabolism and blood vessels were mixed and often null. The authors called clinical effectiveness for anti-aging inconclusive.
A 2025 meta-analysis found the evidence does not support NR or NMN for preserving muscle mass and function in adults over 60. A 2026 meta-analysis of 15 NMN trials found no effect on weight, fasting glucose, HbA1c, cholesterol or systolic blood pressure.
The government mouse test
The National Institute on Aging's Interventions Testing Program tests compounds for life span in mice. Its results table, last updated in April 2026, lists nicotinamide riboside, tested in the 2016 cohort, with no increase in median or maximum life span.
That matches our page on longevity supplements, which reports the same result. A null result in mice does not settle the question for people, but it removes one of the main arguments made for NR.
Where NMN stands with the FDA
In October 2022, FDA told a company that NMN was excluded from the legal definition of a dietary supplement, because it had been authorized for study as a drug. On September 29, 2025, responding to a citizen petition, FDA reversed course and concluded that NMN is not excluded.
That ruling is about legal status, not about whether NMN works. FDA also wrote that companies still cannot skip the new dietary ingredient notification requirement. Ask your doctor before adding an NAD product, especially if you take other medicines.
Related questions
Do NAD IV drips or injections work?
There is no outcome evidence. The 2026 review found no eligible outcome trials of intravenous or intramuscular NAD itself for anti-aging or wellness.
Is NMN safe?
In a 2026 meta-analysis of trials lasting 14 days to 24 weeks, NMN did not increase adverse events or liver enzymes. Long-term safety has not been studied.
Does NR extend life in mice?
Not in the NIA testing program. Nicotinamide riboside showed no increase in median or maximum life span.
Read next
Sources
- Gallagher et al., Ageing Research Reviews: NAD+ supplementation for anti-aging and wellness, a PRISMA-guided systematic review (2026)
- Martens et al., Nature Communications: Chronic nicotinamide riboside supplementation in healthy middle-aged and older adults (2018)
- Yoshino et al., Science: Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women (2021)
- National Institute on Aging: Interventions Testing Program, Supported Interventions (updated April 2026)
- FDA: Response to citizen petition on the regulatory status of NMN, Docket FDA-2023-P-0872 (September 29, 2025)
Published 2026-10-07 · Last checked 2026-10-07
Educational content, not medical advice. Made for the United States.