Despite its classification as an anti-aging supplement, there is no evidence to suggest that NMN directly results in a younger appearance. Some people report smoother skin after taking NMN, but this could be due to a placebo effect.
In addition, the main factor contributing to skin ageing is exposure to the sun. Ultraviolet radiation is the most potent skin ageing agent, so using high factor sunscreens and avoiding sunbeds are the most effective means of maintaining a youthful appearance.