A Narrative Review of Nicotinamide Adenine Dinucleotide (NAD)+ Intermediates Nicotinamide Riboside and Nicotinamide Mononucleotide for Keratinocyte Carcinoma Risk Reduction

Abstract

Oral nicotinamide (NAM) supplementation has been shown to decrease the incidence of keratinocyte carcinoma (KC) in high-risk skin cancer patients. NAM is a nicotinamide adenine dinucleotide (NAD+) intermediate and thus directly leads to increased NAD+. This increase in NAD+ is believed to be responsible for NAM's impact on keratinocyte carcinoma risk. NAD+ has protective cellular effects and is a necessary cofactor for DNA repair, helping to prevent potentially oncogenic mutations. Nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) are NAD+ intermediates like NAM; however, their protective roles on cellular DNA and effects on cancer have been under-explored. Research into cellular metabolism and aging suggests that NR and NMN can lead to greater increases in NAD+ vs NAM. NR and NMN are safe and well-tolerated and are consequently currently undergoing investigation as agents able to protect against age-associated disease caused by NAD+ depletion. We hypothesize that oral supplementation with NR or NMN may lead to greater reductions in KC than NAM.