Nicotinamide riboside (NR): the best-trialled NAD+ precursor, and what it has shown

What it means

Nicotinamide riboside is a form of vitamin B3 discovered in milk and converted to NAD+ via the NRK enzymes. It is sold under the Niagen trade name and in generic capsules, usually 250–1,000 mg per day. It has generally recognised-as-safe status in the US and a novel-food authorisation in the EU, which NMN does not.

Like NMN, it raises whole-blood NAD+ within days; the two are compared in detail on the NAD+ entry.

Why it matters for longevity

NR matters mostly as the test case for the NAD+ hypothesis. If raising NAD+ in people produced the metabolic and mitochondrial benefits seen in old mice, NR trials would have shown it. They have raised NAD+ reliably and shown small or no functional changes, which is informative in itself.

What the evidence says

Martens 2018 (Nature Communications): 24 adults aged 55–79, 1 g/day for six weeks, crossover. Blood NAD+ up about 60%; no significant change in blood pressure, arterial stiffness or exercise capacity. Dollerup 2018: 40 obese men, 2 g/day for twelve weeks; no change in insulin sensitivity, mitochondrial respiration or body composition. Elhassan 2019: 12 older men, 1 g/day for 21 days; raised muscle NAD+ metabolites, no change in mitochondrial function, some reduction in inflammatory cytokines.

A 2023 trial in Parkinson's disease reported mild symptom improvement on 1 g/day; a heart-failure pilot showed improved mitochondrial respiration in blood cells. Nothing on lifespan or disease prevention.

How to measure or use it

• NR is safe across trials at 1–2 g/day for up to twelve weeks; the common side effects are mild nausea and flushing.
• Judge a trial of it on HOMA-IR, hs-CRP, performance or subjective energy over 8–12 weeks, then decide.
• The NAD+/NADH ratio responds to training and fasting without a supplement; see the NAD+ entry.

Related

• Mitochondria and energy — the NR trials next to the exercise data
• Supplements that have evidence — the ranking
• NAD+ IV and injections — the infusion alternative, graded