Vitamin B3 (Niacin)
vitamin
ApprovedGeneral information about nutrients. No diagnosis, no medical advice. If you take medication, are pregnant or have a medical condition, talk to your doctor before taking supplements.
Overview
Water-soluble B vitamin, available as niacin or nicotinamide. Niacin contributes to normal energy-yielding metabolism. Niacin contributes to normal functioning of the nervous system.
Interactions
The conversion of tryptophan to niacin (B3) requires FAD (the active form of B2) as a cofactor for kynurenine-3-monooxygenase in the kynurenine pathway.
B6 (as PLP) is a cofactor for kynureninase in the tryptophan-to-niacin conversion pathway. B6 deficiency reduces endogenous niacin production.
Research status
Precursor of NAD+. The related forms NR and NMN are being studied in animal models and in humans.
Top 5 food sources
Expert opinions
Bryan Johnson Blueprint
The Blueprint protocol skips classical niacin (to avoid flush and LDL-particle shifts) and instead uses 375 mg nicotinamide riboside (NR) daily — a direct single-step NAD+ precursor that bypasses the need for salvage-pathway enzymes. Johnson pairs it with TMG (trimethylglycine) to buffer the methyl groups consumed when excess nicotinamide is cleared by NNMT. He tracks NAD+/NADH ratio and whole-blood NAD levels quarterly; his reported values sit in the top 1% for his age group. Niacin-equivalent activity is preserved without flushing, hepatotoxic risk, or insulin-resistance signals seen with sustained-release niacin.
Recommended dose: ~50 mg niacin equivalent
Source: Blueprint Protocol
NIH
The 35 mg NIH Tolerable Upper Intake Level applies only to supplemental niacin (nicotinic acid) and is set to avoid the prostaglandin-mediated 'niacin flush', an intense facial redness, itching, and warmth that begins around 50 mg. The UL does not apply to niacin from food, nor to nicotinamide, which does not cause flushing but carries its own risk of hepatotoxicity above 3 g. Sustained-release niacin formulations are more strongly associated with liver injury than immediate-release. RDA is 16 mg NE (niacin equivalents) for men and 14 mg for women.
Recommended dose: 14–16 mg
Source: NIH
Dr. Strunz
Strunz uses niacin (nicotinic acid), starting at 50 mg with food and escalating slowly to build flush tolerance. He also uses niacin as an NAD+ precursor. Niacin contributes to normal energy-yielding metabolism. When NAD+ is the only goal, he may switch to nicotinamide or NMN to avoid the flush.
Recommended dose: 50–200 mg
Source: Dr. Strunz
Expert profiles summarise publicly available statements. The named people do not cooperate with Stackwell and have not authorised these summaries. Not medical advice.
UL varies widely between profiles. Form matters (niacin vs nicotinamide vs NR).