Peptides and retinol for anti-aging: what the skin science actually shows

What did @kristingl actually say?

The creator, who identifies as a "beauty product developer," walked through a six-step Korean skincare routine built around three main anti-aging claims: that NAD+ "pushes your skin to repair itself," that 50 peptides in one formula offer meaningful diversity even if not higher concentration, and that layering retinol with peptides and NAD+ is safe and effective. She also credited bakuchiol as a "retinol alternative" that increases cell turnover, and framed topical collagen as primarily a hydration ingredient rather than a structural one.

She was measured in places, noting that under-eye patches with "a sprinkle of retinol" won't erase fine lines, and acknowledging that peptide count doesn't equal potency. That kind of hedging is rarer than it should be on skincare TikTok, and it's worth noting.

Does the science back this up?

Partially, yes. The peptide and retinol claims are on solid enough ground. The NAD+ topical claim is where things get shakier, and it's also where the most hype lives.

Retinol's effect on cell turnover is one of the better-supported claims in dermatology. Kligman et al. (1986, Journal of the American Academy of Dermatology) established retinoids as effective for photoaging, and that body of evidence has only grown. Bakuchiol's comparison to retinol has some backing too: Dhaliwal et al. (2019, British Journal of Dermatology) found bakuchiol comparable to retinol in reducing wrinkles and hyperpigmentation with less irritation, though the sample was small (44 participants).

Peptides are trickier. Specific peptides like GHK-Cu (copper peptide) have legitimate research behind them for collagen stimulation, but the evidence quality varies widely by peptide. A formula listing 50 peptides tells you almost nothing about efficacy without knowing concentrations and which specific peptides are included.

Topical NAD+ is the weakest link here. The internal NAD+ longevity research, driven by work like Yoshino et al. (2018, Cell Metabolism), involves oral precursors like NMN and NR, not topical application. Skin penetration of NAD+ and its precursors through topical products has very limited published evidence.

What did they get wrong (or right)?

She got the collagen-in-cleanser call right. Saying topical collagen is "more for hydration" is accurate. The collagen molecule is too large to penetrate skin and stimulate dermal collagen synthesis. That's a common misconception she correctly avoided amplifying.

The bakuchiol-as-retinol-alternative framing is mostly fair but leans on one small study. It's not a settled comparison, and calling it "commonly known as a retinol alternative" overstates the consensus slightly.

The NAD+ claim, though, is the problem. Saying NAD+ "pushes your skin to repair itself" as if topical NAD+ replicates the cellular energy and DNA-repair mechanisms studied in oral supplementation research is a significant leap. The mechanism being described, NAD+ as a coenzyme in cellular repair pathways, is real. Whether a topical essence delivers it to functioning skin cells at relevant concentrations is not established. She presented this as settled fact when it is not.

The "you can absolutely layer" retinol with peptides and NAD+ claim is reasonable. There's no strong evidence of harmful interactions between these ingredients at cosmetic concentrations.

What should you actually know?

Retinol remains one of the few topical actives with decades of peer-reviewed support for reducing visible signs of photoaging. If anti-aging is your goal, that's still the most evidence-backed ingredient in this routine by a wide margin.

Peptides are promising but uneven. GHK-Cu specifically has the most published support for collagen-related effects (Pickart and Margolina, 2018, Cosmetics). A product advertising 50 peptides is a marketing number, not a clinical one. Ask which peptides, not how many.

Topical NAD+ is being marketed aggressively right now, but the science driving that excitement is almost entirely based on oral supplementation studies. Treating the ingredient as equivalent to that research in a serum is premature. It may do something useful at the skin surface level, but "repair itself" is a claim that outpaces the available evidence for topical delivery.

Bakuchiol is a reasonable option for people who can't tolerate retinol, but it should not be marketed as a proven equivalent. It's a gentler alternative with early supportive data, not a replacement backed by the same depth of evidence.