The differential impact of three different NAD(+) boosters on circulatory NAD and microbial metabolism in humans

Christen S, Redeuil K, Goulet L, Giner MP, Breton I, Rota R · Nature Metabolism

The first head-to-head human comparison. NR and NMN roughly doubled whole-blood NAD+ and did so comparably — differences versus placebo of 49.4 µM (95% CI 39.5 to 59.3) for NR and 43.1 µM (32.7 to 53.4) for NMN, both p<0.001 — while plain nicotinamide did not (p=0.461), its effect being acute and transient rather than sustained. Ex vivo work traced the effect to gut microbial conversion of NR and NMN into nicotinic acid, which was the potent booster in whole blood; NMN, NR and nicotinamide were not.

Population

Healthy adults, four parallel arms

Intervention

14 days of nicotinamide riboside 1,000 mg/day, NMN 1,000 mg/day, or nicotinamide 500 mg/day

Comparator

Placebo (microcrystalline cellulose)

Limitations

Open-label, 14 days, healthy adults, biochemical endpoints only. Conducted at Nestlé Research by Nestlé scientists. The mechanistic conclusion — that the precursors work through a gut detour — is inferred from ex vivo fermentation rather than measured in vivo.