What did @katgosik actually say?
She described starting GHK-Cu two weeks ago and NAD supplementation three months prior. Her stated reason for NAD: "mental brain function and not having that afternoon crash." For GHK-Cu, she's waiting on results, noting "I think it takes about four weeks to really show in your skin and your hair." She asked her audience what else she should stack.
To be fair, she's not making dramatic medical claims here. She framed both compounds as personal experiments and openly admitted she's noticed nothing from GHK-Cu yet. That kind of epistemic humility is rare in the peptide content space. Still, the video casually invites follower-sourced stacking advice, which carries real risk given that peptide interactions aren't well studied in humans.
Does the science back this up?
Partially, depending on the compound. NAD precursors have decent clinical backing for some energy-related outcomes. GHK-Cu is more complicated.
On NAD: the human data is thin but promising. Yoshino et al. (2021, Science) showed nicotinamide riboside improved muscle insulin sensitivity in older adults. Remie et al. (2020, Nature Communications) found NMN supplementation increased NAD levels in blood. However, most studies use oral NMN or NR, not IV NAD, and "afternoon crash" specifically has not been a primary endpoint in any major trial. The mechanism is real; the specific subjective benefit she describes is plausible but not proven.
On GHK-Cu: the evidence base is almost entirely preclinical. Pickart et al. published extensively on GHK-Cu's role in wound healing and collagen synthesis in cell and animal models, but randomized controlled trials in humans are sparse. A 2015 review by Pickart and Margolina (Journal of Aging Research) summarized tissue repair effects without providing human trial data. Her four-week timeline for skin changes is not drawn from clinical literature; it appears to be community consensus, not science.
What did they get wrong (or right)?
She got a few things right. Acknowledging NAD is not a peptide shows she's done at least some homework. Saying she hasn't noticed GHK-Cu results yet and expecting a longer timeline is more honest than most creators who claim results within days.
Where she's on shakier ground: the four-week skin and hair claim for GHK-Cu has no specific clinical backing. There's no published human trial establishing a four-week onset for visible skin changes from GHK-Cu supplementation. That timeline appears to come from anecdote and forum consensus, not data.
The bigger concern is the open call for stacking recommendations from followers. GHK-Cu combined with other peptides like BPC-157 or TB-500 has zero human safety data as a combination. Crowdsourcing your peptide stack from TikTok comments is not a substitute for clinical oversight, and framing it as casual curiosity doesn't reduce the risk.
What should you actually know?
GHK-Cu is a naturally occurring copper-binding peptide. Its cell-culture and animal data on collagen, wound healing, and inflammation are genuinely interesting. But interesting preclinical data has failed to translate to humans more times than it has succeeded. Until there are well-designed human trials, any specific claim about what it does to your skin or hair in a defined timeframe is speculation.
NAD supplementation has more human evidence behind it, though mostly for metabolic and not cognitive endpoints. If someone reports feeling more alert and less fatigued after three months, that's hard to dismiss entirely. But placebo effects in open-label self-experimentation are substantial, and "afternoon crash" is not a validated clinical outcome.
Both compounds are available through compounding pharmacies and telehealth platforms. Neither is FDA-approved for the uses described. That doesn't make them dangerous by default, but it does mean quality control, dosing standards, and safety monitoring vary widely. Anyone considering these should be working with a licensed clinician, not a comment section.