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A new review of recent human NAD+ research argues that the classic narrative, “NAD+ declines with age”, is probably too simplistic.

Key Points

• Whole-blood NAD+ does not consistently decline with age in newer studies
• Tissue NAD+ (muscle, skin, brain) often does decline with aging
• Physically active older adults can maintain youthful muscle NAD+ levels
• NAD+ response to supplementation varies substantially between individuals
• Blood NAD+ may reflect intervention response better than biological aging itself

This is an important shift in the field. The newer data doesn’t invalidate NAD+ biology but gives it new nuance. The emerging picture is that NAD+ appears to be:

• Tissue-specific
• Highly dynamic
• Influenced by health status, activity level, and disease burden
• More individualized than previously thought

This is a reminder that biomarkers measured in blood don’t always represent what’s happening inside active tissues.

Full Article: https://renuebyscience.com/blogs/scientific-evidence-library/nad-aging-blood-biomarker-human-study

A 2026 trial examined whether combining NR with structured exercise could improve fitness in people with Friedreich’s ataxia, a neurodegenerative condition associated with mitochondrial dysfunction and impaired energy production.

Key Points

• NR + exercise increased VO2 by ~12.7%
• Exercise alone improved VO2 by ~9.5%
• NR alone improved VO2 by ~5%
• Control group declined by ~2.4%

The strongest effects came from combining NAD+ support with exercise, which fits the broader idea that raising NAD+ may work best when paired with mitochondrial activity and adaptation.

Full Article: https://renuebyscience.com/blogs/scientific-evidence-library/nr-exercise-improves-fitness-in-friedreichs-ataxia

A randomized clinical trial in 80 adults with eczema found that 10 mg melatonin nightly for 4 weeks improved both skin symptoms and sleep quality.

Key findings

• Eczema severity improved significantly
• Itching intensity decreased
• Sleep quality improved, including falling asleep and staying asleep

Sleep disruption and inflammation are linked to eczema. The study suggests melatonin may help through multiple pathways, like circadian regulation, antioxidant effects, and modulation of inflammatory signaling. The study represents an interesting example of a compound usually associated with sleep showing measurable dermatological benefits as well.

Full Article: https://renuebyscience.com/blogs/scientific-evidence-library/melatonin-improves-skin-and-sleep-quality

A randomized, double-blind crossover study examined ashwagandha extract (21 mg/day) in overweight men aged 40–70 over 8 weeks.

Key findings

• Testosterone increased by ~14.7% vs placebo
• DHEA-S increased by ~18%
• No significant changes in cortisol or estradiol
• Effects declined after discontinuation

Summary

Participants also reported improvements in fatigue and well-being, though these occurred in both placebo and treatment phases.

The data suggests ashwagandha may provide support for age-related androgen decline, but effects appear dependent on continued use. As always, magnitude and clinical relevance depend on baseline levels and individual response.

Full Article: https://renuebyscience.com/blogs/scientific-evidence-library/ashwagandha-testosterone-human-study

A 2026 meta-analysis of 10 randomized controlled trials evaluated the effects of NMN (250–1500 mg/day) on blood pressure.

Key Points:

• Diastolic blood pressure decreased by about 2.15 mmHg
• Systolic blood pressure showed a downward trend
• Adults 60+ saw ~3.9 mmHg reduction in SBP
• NMN was well tolerated across trials

Details:

Even small reductions in blood pressure can have positive effects at the population level. A ~2 mmHg drop in DBP has been associated with reduced cardiovascular and stroke risk. The data suggests NMN may provide modest support for vascular health, particularly in older adults where NAD+ levels decline.

Full Article: https://renuebyscience.com/blogs/scientific-evidence-library/nmn-supports-healthy-blood-pressure-in-adults-evidence-from-human-trials

A 2026 clinical study examined how NMN and NR (1,200 mg/day) affect NAD+ levels in both blood and brain.

Key Points:

• Blood NAD+ increased gradually and plateaued after ~2 weeks
• Brain NAD+ rose to about 40% above baseline after 4 weeks
• Effects were consistent in both healthy individuals and Parkinson’s patients
• NAD+ declined gradually over 2–3 weeks after stopping

This is one of the clearer human timelines for NAD+ kinetics. The data suggests NAD+ elevation is cumulative, not immediate, and requires consistent intake over weeks to fully manifest, especially in the brain.

Full Article: https://renuebyscience.com/blogs/scientific-evidence-library/nmn-nr-increase-nad-in-blood-and-brain