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

This 2026 systematic review searched six databases through May 13, 2026 and included 15 parallel randomized adult NMN trials.

Short-term NMN did not show a clear increase in overall, serious, withdrawal-related or system-specific adverse events, and ALT and AST were not significantly elevated. At the same time, pooled analyses did not show significant benefits for body weight, BMI, fasting glucose, HbA1c, lipid profiles or systolic blood pressure.

A small diastolic-blood-pressure reduction and a non-significant HOMA-IR trend were reported, but the authors characterized these as preliminary signals requiring larger and longer trials.

• Fifteen parallel randomized trials were included; ten contributed to safety analyses.
• Doses ranged from 250 to 2,000 mg/day and durations from 14 days to 24 weeks.
• No clear increase was found in overall, serious, withdrawal-related or system-specific adverse events.
• ALT and AST were not significantly elevated.
• Body weight, BMI, fasting glucose, HbA1c, lipid profiles and systolic blood pressure showed no significant pooled benefit.
• Diastolic blood pressure decreased slightly; HOMA-IR showed a non-significant downward trend.

• The longest included trials lasted 24 weeks, so long-term safety remains unknown.
• Trials were generally small and heterogeneous.
• Some NMN-related formulations may not be identical to standard NMN supplements.
• Many metabolic outcomes were secondary endpoints.
• Rare adverse events cannot be ruled out by the current sample sizes.