Safety and Metabolism-Related Outcomes of Oral Nicotinamide Mononucleotide Supplementation in Adults: A Systematic Review and Meta-Analysis

Yang W, Huang J, Tang Z, Chen C, Sun Y · Nutrients

NMN did not increase overall adverse events, serious adverse events, withdrawals, system-specific events, ALT or AST. No effect on body weight, BMI, fasting glucose, HbA1c, lipids or systolic pressure. Diastolic pressure fell by 2.43 mmHg (95% CI -4.21 to -0.66, p=0.007, I-squared 0%) across 11 comparisons in 339 participants, and HOMA-IR trended down without reaching significance.

Population

Adults across 15 randomised trials (10 contributing safety data), NMN 250-2,000 mg/day for 14 days to 24 weeks

Intervention

Oral NMN or NMN-containing preparations

Comparator

Placebo, blank control or matched background intervention

Limitations

Maximum trial duration 24 weeks — this establishes short-term tolerability, not long-term safety. GRADE certainty came out moderate for the liver enzymes, weight, BMI, fasting glucose, triglycerides and total adverse events; low for HbA1c, LDL-C and both blood pressures; and very low for HOMA-IR and for serious adverse events, which is the outcome a safety synthesis most needs. The reviewers themselves treat the diastolic fall as an exploratory signal, since blood pressure was not a primary endpoint in most of the pooled trials and many outcomes were compared.