Nicotinamide riboside (NR, NR chloride / Niagen) — evidence review

Regulatory status: dietary supplement / novel food / niacin source — not a prescription drug. See section 7.

• Raise NAD+ (blood, muscle, brain) — **surrogate**
• Improve exercise performance / muscle function
• Improve insulin sensitivity / glucose metabolism
• Improve lipids (LDL-C, triglycerides, HDL-C)
• Lower blood pressure / arterial stiffness
• Slow neurodegeneration (Parkinson’s, cognition)
• Improve liver fat / NAFLD
• Reduce inflammation
• Extend human lifespan / healthspan (longevity)

Nicotinamide riboside chloride is a well-characterised oral NAD+ precursor that **reproducibly raises blood NAD+ and the NAD metabolome** at 300–1,000 mg/day, without the flushing of nicotinic acid, in multiple RCTs. That surrogate finding is **strong**. Every marketed clinical claim — insulin sensitivity, lipids, blood pressure, exercise, liver fat, neurodegeneration, longevity — is either **null in the best human trials**, **exploratory and unreplicated**, or **not tested in humans**. The highest-quality metabolic experiment (Dollerup 2018, 2 g/day, 12-week clamp in obese men) is a clean negative. Martens’ 9 mmHg SBP figure is a post-hoc subgroup the authors themselves declined to infer from. NADPARK did not move MDS-UPDRS in the randomised comparison. There is no human longevity trial. Inflammation-marker reductions (Elhassan, Norheim COPD IL-8, HF PBMCs) are the least-bad clinical-domain signal and still are not disease-modifying outcomes.