Effects of Nicotinamide Mononucleotide on Glucose and Lipid Metabolism in Adults: A Systematic Review and Meta-analysis of Randomised Controlled Trials

Chen F, Zhou D, Kong AP, Yim NT, Dai S, Chen YN · Current Diabetes Reports

Null on every pooled endpoint: no significant effect on fasting glucose, fasting insulin, HbA1c or any lipid fraction. HOMA-IR came closest, a pooled reduction of 0.27 (95% CI -0.01 to 0.55, p=0.06, I-squared 0%) across three trials, and lost even that when one of the three was removed — a trial whose difference the reviewers attribute to the placebo group deteriorating rather than the NMN group improving. Five of the eight trials reported blood NAD+ rising. Adverse events, whatever their attributed cause, tended to be more frequent in arms taking 1,000 mg/day or more.

Population

342 middle-aged and older adults across 8 randomised trials, mainly non-diabetic

Intervention

NMN 250-2,000 mg/day for 14 days to 12 weeks

Comparator

Placebo

Limitations

Eight small trials in mostly healthy adults — the populations least likely to show metabolic improvement — over 14 days to 12 weeks. Heterogeneity was nil for almost every outcome but above 50 per cent for fasting insulin and HbA1c. One trial reported its results only as plots and could not be pooled, and no analysis reached ten trials, so publication bias could not be tested.