ANABIOTICASubmit a source
Research

NAD+ Precursors

Nicotinamide riboside and NMN reliably alter NAD-related biomarkers, but human trials have not established broad improvements in function, disease prevention, or longevity.

Emerging
Evidence rating
Evidence review

What the evidence says

Nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) are vitamin B3-related precursors intended to raise nicotinamide adenine dinucleotide, a cofactor involved in energy metabolism and cellular signaling. Raising a blood metabolite is target engagement, not proof of rejuvenation.[1]

A six-week crossover trial in 24 healthy middle-aged and older adults found that NR raised NAD-related metabolites and was generally tolerated, with exploratory blood-pressure and arterial-stiffness signals. The sample was too small and short to establish cardiovascular protection.[1]

In insulin-resistant men with obesity, 12 weeks of NR raised NAD metabolites but did not improve insulin sensitivity, glucose metabolism, lipid accumulation, or body composition. A small mild-cognitive-impairment trial found biochemical changes without a significant improvement in cognition.[2][3]

Meta-analyses of NR and NMN trials do not show a consistent improvement in muscle mass, strength, physical function, glucose control, or lipid outcomes. Different compounds, doses, assays, and enrolled populations should not be collapsed into a single proven anti-aging effect.[4][5]

Potential benefits

  • Reliably raises selected NAD-related metabolites, confirming oral bioavailability and biological activity.[1]
  • Provides a useful human research tool for testing whether NAD biology translates into clinical benefit.[3][5]

Side effects and cautions

  • Short trials report mostly mild gastrointestinal symptoms, headache, fatigue, or no clear excess, but are underpowered for rare harms.[2][5]
  • Long-term high-dose safety, medication interactions, and effects in cancer or major organ disease remain uncertain.[4]
How we scored it

Evidence breakdown

Short randomized trials demonstrate bioavailability and generally acceptable near-term tolerability, while clinical outcomes are inconsistent, small, and product-specific.

Clinical relevanceLow

Most studies prioritize NAD metabolites and short-term surrogate outcomes rather than disability, disease, or survival.

Study qualityModerate

Randomized placebo-controlled trials exist, but they are usually small and brief.

Safety dataLow

Near-term trial safety is reassuring; chronic high-dose use and diverse older populations remain under-studied.

References

Full source list

  1. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults

    Nature Communications · 2018

  2. Nicotinamide riboside supplementation is not associated with altered methylation homeostasis or insulin sensitivity in obese men

    American Journal of Clinical Nutrition · 2018

  3. Nicotinamide riboside supplementation in mild cognitive impairment: a randomized controlled trial

    GeroScience · 2024

  4. The Effect of Nicotinamide Mononucleotide and Riboside on Skeletal Muscle Mass and Function: A Systematic Review and Meta-Analysis

    Journal of Cachexia, Sarcopenia and Muscle · 2025

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

    Current Diabetes Reports · 2024