PeptideCompareNAD+ — Precursors
NAD+ is a coenzyme involved in energy metabolism, DNA repair and sirtuin activity, and its levels are reported to decline with age. This topic covers NAD+ and its precursors NMN, NR, niacin and niacinamide.
The pathway at a glance
NMN, NR, nicotinamide (NAM) and nicotinic acid (niacin, NA) are all precursors that cells convert into NAD+ through different biosynthetic routes.
The precursors
NMN. Nicotinamide mononucleotide sits one step before NAD+ in the salvage pathway. Human trials exist but are mostly small and short, and long-term outcome data are limited. Product quality varies, so researchers check the COA for purity and assay value.
NR. Nicotinamide riboside is converted to NMN and then to NAD+ inside cells. Human trials have measured its effect on blood NAD+ levels. A patented form is sold as Tru Niagen.
Niacin (NA). Nicotinic acid is the longest-known precursor, with decades of clinical use as a lipid-modifying drug. A well-known side effect is skin flushing.
NAM. Nicotinamide does not cause flushing. In laboratory studies it inhibits sirtuins at high concentrations, which is why it is discussed separately from the other precursors.
NAMN. A newer precursor entering via the Preiss-Handler pathway. Early research suggests it may avoid NAMPT bottlenecks that limit NMN efficacy. Limited human data so far. Watch this space.
NRH. A reduced form of NR that some studies show raises NAD+ more powerfully than NMN or NR in mice. Very new, limited human data. Not widely commercially available yet.
How the precursors compare
NMN and NR have the strongest direct human evidence. NMN is the most expensive to produce and quality varies, so a verified COA matters; NR is a well-studied alternative at lower cost. NA and NAM are inexpensive but come with caveats: NA commonly causes flushing, and NAM can inhibit sirtuins at high intake. NAMN and NRH are still at the research stage. This article describes the research and does not recommend any product or intake.