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Placebo-controlled randomized double-blind parallel-group trial of the safety of overdose intake of nicotinamide mononucleotide

Ryota Nakajima, Hidekazu Watanabe, Kunio Nakata, Kei Yamana, Masahiko Tokushima
Fundamental Toxicological Sciences 2025 12(3):67-77

Bibliography

DOI
10.2131/fts.12.67
Competing interests
Ryota Nakajima, Hidekazu Watanabe, Kunio Nakata and Kei Yamana were affiliated with Teijin Limited and NOMON Co., Ltd.; the tested NMN was manufactured by Teijin Limited.

Study snapshot

DesignPlacebo-controlled, randomized, double-blind, parallel-group safety trial.
ModelThirty healthy Japanese adults aged 20–64 years.
Samplen=30; 10 each to 1500 mg/day, 750 mg/day and placebo.
InterventionNMN 750 mg/day, NMN 1500 mg/day, or placebo.
Duration4 weeks.
EndpointsMedical interviews and subjective symptoms; Body weight and BMI; Blood pressure and pulse; Hematology; Blood chemistry; Urinalysis; Blood NAD+; Telomere length

What the study showed, in plain terms

This high-dose safety trial randomized 30 healthy adults to placebo, 750 mg/day NMN or 1,500 mg/day NMN for four weeks.

No participant dropped out and the investigators reported no problematic clinical or laboratory safety findings. Blood NAD+ increased, while telomere length did not change. The study is informative for short-term high-dose tolerability but too small and brief to define long-term safety.

Key findings

  • No dropouts occurred among the 30 participants.
  • No problematic safety findings were identified at doses up to 1500 mg/day for four weeks.
  • Blood NAD+ increased with NMN.
  • Telomere length was not affected.

What this study can and cannot tell us

Thirty participants over four weeks is insufficient to identify rare, delayed or cumulative toxicity. Four of five authors were affiliated with companies that manufacture or sell the tested NMN.

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Dr. Khaled Mahmoud, MBBChCritical Care Medicine, Longevity Science & Editorial Direction Dr. Amr Yasser, PhDCardiometabolic, Musculoskeletal, Gut & Bioavailability Dr. Abdulla Mostafa, PhDCellular Senescence, Neurological, Mitochondrial & Brain-Ageing Biology