Skin is the most visible measure of how our body is doing, and the one we tend to fuss over most. It's also one of the tissues where NAD+ decline has been most clearly measured in humans, which is partly why skin keeps showing up in the longevity conversation.
What the skin research found
A 2018 paper by Massudi and colleagues, published in PLOS One, measured NAD+ levels directly in human skin samples across a wide age range. The pattern was clear: NAD+ in skin tissue dropped significantly with age, roughly halving between younger and older adults. Multiple groups have since reported similar declines in other tissues, but skin remains one of the cleanest demonstrations of the trend.
This matters because skin cells turn over constantly. The outer layer is in a permanent cycle of replacement, with new cells produced underneath and old ones shed at the surface. That turnover requires energy, and NAD+ is part of how cells produce it. When the raw material drops, the work doesn't stop, but it gets noisier.
The gap between mechanism and "skincare claims"
It's tempting to draw a straight line from "NAD+ declines in skin" to "NMN will give you better skin." We're going to resist that line, because the published human research doesn't yet support it cleanly. What the research currently supports is that NMN at studied doses raises blood NAD+ metabolites, and that NAD+ is involved in cellular processes including those that happen in skin.
That's a meaningful mechanism. It's not a skincare claim. The cosmetics industry has a habit of overpromising, a habit we have no interest in copying. If your skin matters to you, the boring stuff still beats the exciting stuff: sunscreen, sleep, hydration, not smoking, and a basic routine you actually stick to. Those are the interventions that have decades of evidence behind them.
Where NMN fits, honestly
For people in the biohacking community who already take NMN for general cellular wellbeing, the skin angle is one part of a broader rationale. They're not betting on it as a cosmetic intervention. They're paying attention to cellular biology that runs underneath every tissue, including skin, and treating it as one input in a longer-term routine.
NMN as part of a daily routine for people interested in cellular wellbeing as they age. Not a skin product, not a treatment: a precursor to a coenzyme that naturally declines, taken because the underlying biology matters.
One last thing
If anyone (supplement brand, skincare brand, influencer) promises a measurable visible result from a capsule, walk away. The real version of this story is more interesting than the marketing one anyway.
