NMN / NAD+ Precursors Research

This systematic review with meta-analysis pooled data from randomized controlled trials examining the effects of oral NMN supplementation on glucose and lipid metabolism in adults. The review searched multiple databases for studies comparing NMN to placebo in human participants, focusing on metabolic outcomes including fasting blood glucose, insulin, and lipid panel markers.

The meta-analysis found that NMN supplementation significantly reduced fasting blood glucose levels compared to placebo. Improvements were also observed in lipid metabolism markers, suggesting NMN may have meaningful metabolic benefits beyond its established role in boosting NAD+ levels. Subgroup analyses indicated that the effects were influenced by dosage and supplementation duration.

These findings provide the first pooled quantitative evidence from human RCTs supporting NMN's role in metabolic health. The results strengthen the case for NMN as a metabolic intervention, though the authors note the relatively small number of available trials and the need for larger, longer-duration studies to confirm these effects.

This systematic review synthesized evidence from randomized controlled trials examining the effects of NMN supplementation on physical performance parameters in humans. The review identified and analyzed multiple RCTs that measured outcomes such as aerobic capacity, walking endurance, grip strength, and exercise performance in participants taking NMN compared to placebo.

The findings consistently demonstrated improvements in physical performance across the included studies. Participants taking NMN showed enhanced aerobic capacity, improved walking endurance (six-minute walk test), and better grip strength. These benefits were observed across different populations including healthy middle-aged adults and older individuals, suggesting NMN may counteract age-related physical decline through its role in boosting NAD+ levels and supporting mitochondrial function.

The review highlights that while the evidence is promising and directionally consistent across studies, the field is still limited by a small number of available RCTs, relatively short intervention periods, and modest sample sizes. The authors conclude that NMN shows genuine potential as an intervention for maintaining physical function but call for larger and longer trials to establish definitive clinical recommendations.

This rigorous multicenter, double-blind, placebo-controlled trial investigated the dose-dependent effects of NMN supplementation in healthy middle-aged adults aged 40-65. Participants were randomized to receive 300 mg, 600 mg, or 900 mg of NMN per day, or placebo, for 60 days. The study measured blood NAD+ concentrations, clinical safety markers, and physical performance outcomes including the six-minute walk test.

All three NMN doses significantly increased blood NAD+ levels compared to placebo, confirming oral NMN bioavailability in humans. The 600 mg and 900 mg groups showed the most pronounced increases. Notably, the study demonstrated improvements in walking endurance as measured by the six-minute walk test, suggesting functional physical benefits from NMN supplementation.

Safety assessments showed NMN was well-tolerated at all doses with no serious adverse events. Clinical laboratory values, vital signs, and adverse event profiles were comparable between NMN and placebo groups. This study is particularly valuable as one of the first well-designed dose-response trials in humans, providing evidence for both the safety and efficacy of NMN at commonly used supplement doses.

This randomized, placebo-controlled trial examined NMN's effects on physical function in healthy older men.

Protocol:

• 42 healthy older men (65+ years)
• 250mg NMN daily for 12 weeks
• Measured physical performance and blood NAD+ metabolites

Key findings:

• Blood NAD+ and related metabolites increased significantly
• Gait speed improved in NMN group
• Grip strength improved
• No significant adverse effects
• Hearing and body composition unchanged

Significance:

Provided evidence that NMN supplementation may improve age-related physical decline, with measurable functional improvements in gait and strength - meaningful outcomes for aging populations.

This landmark study from Washington University was the first rigorous double-blind, placebo-controlled trial of NMN in humans.

Protocol:

• 25 postmenopausal women with prediabetes
• 250mg NMN daily for 10 weeks
• Hyperinsulinemic-euglycemic clamp (gold standard for insulin sensitivity)

Key findings:

• Muscle insulin sensitivity increased ~25%
• Muscle NAD+ metabolite (NMN) increased in NMN group
• No significant changes in body composition
• No adverse effects reported
• Blood NAD+ levels did not change (tissue levels more relevant)

Significance:

Provided first rigorous human evidence that oral NMN supplementation has metabolic effects, though the specific population (prediabetic women) limits generalizability.

This randomized, double-blind, placebo-controlled crossover trial examined NR supplementation in healthy middle-aged and older adults.

Protocol:

• 24 lean, healthy adults (55-79 years)
• 500mg NR twice daily (1,000mg total) for 6 weeks
• Crossover design with placebo

Key findings:

• NAD+ in PBMCs increased ~60%
• Well-tolerated with no serious adverse events
• Trend toward reduced systolic blood pressure (-5 mmHg)
• Trend toward reduced arterial stiffness
• No significant changes in metabolic markers

Significance:

Established that oral NR can effectively raise NAD+ levels in humans and suggested cardiovascular benefits warranting larger trials.