Benefit
Safety & Drug Interactions
Methylation, sirtuin inhibition, and co-therapies.
Moderate human evidence
Long-term NAD+ supplementation draws down methyl donor pools (via nicotinamide methylation to MNA). High-dose nicotinamide can inhibit sirtuins — the opposite of the intended effect. Interactions with cancer therapy, statins, and metformin are actively studied.
Key studies
Scientific Reports · 2019 · PMID 31316207
Safety and metabolism of long-term administration of NIAGEN (Nicotinamide Riboside Chloride)
Conze D, et al.
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Editorial note
NADFaq grades evidence on a 4-tier scale based on human trial quality, sample size, reproducibility, and mechanistic plausibility. This is a conservative framework — many published benefits of NAD+ precursors rest on preclinical (rodent or cell) work that has not yet translated to humans.
How we grade evidence