A 24-week trial shows that high-dose nicotinamide mononucleotide (NMN) can raise blood NAD levels in older adults—but raising a biomarker did not translate into clearer improvements in strength, walking, hearing, or glucose control.
What changed
Published September 25, 2026, the randomized, double-blind, placebo-controlled trial enrolled 62 healthy Japanese adults aged 65 or older; 58 completed it. Participants received 1,250 mg NMN daily or placebo. NMN produced a 3.6-fold increase in circulating NAD levels after 24 weeks.
How strong is the evidence?
This is peer-reviewed human randomized evidence. The placebo comparison and six-month follow-up strengthen confidence that NMN changed NAD levels metabolism. However, no significant benefit appeared in the primary hearing outcome, physical performance, cardiopulmonary function, blood glucose, or HbA1c.
What remains uncertain
The trial was small and excluded many chronic conditions, limiting relevance to less-healthy older adults. Lean-mass and cholesterol signals were exploratory and generally did not survive correction for multiple comparisons. Adverse-event rates were similar, although one NMN participant had asymptomatic liver-enzyme elevations. Three authors worked for the company that supplied NMN and provided technical support.
Why it matters
The study separates biochemical activity from proven anti-aging benefit: NMN clearly boosted NAD levels, but it did not demonstrate better function or longer life. It does not establish a treatment dose or justify changing medical care.
Sources
Igarashi and colleagues, npj Aging, published September 25, 2026. The article-in-press PDF was reviewed directly.
Illustrative stock photograph; the person shown did not participate in the study. Photo: Age Cymru / Unsplash.
