Nicotinamide: An Update and Review of Safety & Differences From Niacin

Reed Huber, BSc; Aaron Wong, MD, FRCPC

Disclosures

Skin Therapy Letter. 2020;25(5):7-11. 

In This Article

Background

Niacin is synthesized from tryptophan, an essential amino acid obtained from dietary sources, including poultry, salmon, and red meat. In the body, niacin is converted to nicotinamide, and like most water-soluble vitamins, it functions as enzyme cofactors. Nicotinamide is the precursor of NAD+ and the reduced form NADP, which are implicated in oxidative phosphorylation and adenosine triphosphate (ATP) production, and function as enzyme cofactors in at least 200 different biochemical reactions.[5]

Actinic keratosis (AK) and nonmelanoma skin cancers (NMSC) are caused principally by ultraviolet (UV) radiation directly damaging DNA in keratinocytes and by immunosuppression. Nicotinamide works at multiple steps to counteract the carcinogenesis of squamous-cell carcinomas (SCC) and basal-cell carcinomas (BCC) (Figure 2). First, by preventing ATP depletion, nicotinamide boosts cellular energy which counteracts the "energy crisis" in photodamaged skin through an array of protective responses within keratinocytes, including DNA repair, anti-inflammatory effects, and by enhancing local cutaneous immunity.[2] Nicotinamide is also the exclusive substrate for poly-ADP-ribose-polymerase (PARP-1), a key enzyme involved in DNA repair.[6] Moreover, nicotinamide reduces the level of immunosuppression that results from UVB irradiation of lymphocytes in the skin through similar mechanisms by enhancing cellular energy and DNA repair enzyme activity without altering baseline immunity.[7,8]

Figure 2.

Proposed chemoprotective actions of nicotinamide.

Comments

3090D553-9492-4563-8681-AD288FA52ACE

processing....