Skin & Longevity Peptides: GHK-Cu, GLOW, Epitalon, NAD+ and SS-31
GHK-Cu, the GLOW blend, Epitalon, NAD+ precursors, and SS-31 sit at very different points on the evidence ladder. In skin and longevity peptides, popularity and evidence are almost inverses — this guide labels each compound honestly.
"Skin and longevity peptides" is where marketing pressure on peptide science is strongest. The compounds in this space — GHK-Cu, the GLOW blend, Epitalon, NAD+ precursors, and SS-31 — sit at very different points on the evidence ladder, from a peptide with real topical human trials to compounds whose human evidence is nearly zero.
This guide walks each one and labels the evidence honestly.
GHK-Cu
GHK-Cu is a copper-binding tripeptide that occurs naturally in the human body and declines with age. It is the most defensible compound in the skin category: topical GHK-Cu has a modest but real base of human research on skin quality and wound healing, plus broad laboratory work on cell signaling, collagen production, and remodeling.
The scope caveat matters. The human work is dermatological and topical. Claims about systemic anti-aging effects go well beyond what those trials support.
Start with GHK-Cu: the copper peptide your body makes, then GHK-Cu in serums vs. as a research peptide for the formulation differences.
Evidence tier: other human data (topical, dermatological); laboratory for systemic claims.
The GLOW blend
GLOW is a marketed blend combining GHK-Cu with BPC-157 and TB-500. Each component has its own research base — GHK-Cu's is the strongest of the three, and the other two rest mostly on animal and laboratory work (see recovery peptides explained).
The blend itself has no published trials. "Blend" is also not a neutral word: combined compounds have no study establishing their combined behavior, and per-component math is the only honest way to reason about concentrations. We cover both the marketing and the arithmetic in the GLOW peptide blend and GLOW vs. KLOW, and our peptide calculator does the per-component math transparently in blend mode.
Evidence tier: components as above; the blend itself: insufficient.
Epitalon
Epitalon (Epithalon) is a synthetic peptide studied for its effects on telomerase — the enzyme involved in maintaining telomere length — primarily in animal and cell models. The theoretical interest is real: telomere shortening is associated with aging at the cellular level.
The human evidence, however, is minimal — small uncontrolled studies at best, with no large randomized trials. The gap between "activates telomerase in a rodent model" and "slows aging in people" is enormous, and the honest answer is that no one has bridged it. Details in Epitalon: the research, honestly explained.
Evidence tier: animal and laboratory; insufficient for human claims.
NAD+ precursors
NAD+ (nicotinamide adenine dinucleotide) is a coenzyme involved in cellular energy metabolism, and NAD+ levels decline with age. The popular compounds are precursors — NMN and NR — meant to raise NAD+ levels. These are not peptides; they are small molecules often sold in the same market.
Human research exists: small trials have measured NAD+ level changes and short-term safety. What does not exist (yet) is large randomized evidence that raising NAD+ levels improves healthspan outcomes in people. The mechanistic story is attractive, which is exactly why it is marketed hard. We cover the distinction in NAD+ explained.
Evidence tier: other human data (biomarker and safety studies); insufficient for outcome claims.
SS-31 (elamipretide)
SS-31 is the most scientifically serious compound on this list — and the least popular in casual discussion. It targets mitochondrial function, binding to cardiolipin in the inner mitochondrial membrane, and it has been through human clinical trials — including randomized controlled trials in several patient populations, with mixed results by indication.
That trial history means SS-31 is a real investigational drug candidate with a real development record, not a forum favorite. The lesson it teaches about the whole skin-and-longevity category: the compounds with the most credible human trial programs are rarely the ones with the loudest marketing. Background in SS-31/elamipretide.
Evidence tier: human RCTs — for specific clinical indications, with mixed results.
Side by side
| Compound | Category | Human evidence | Most-cited claims supported? |
|---|---|---|---|
| GHK-Cu | Peptide | Topical trials | Skin claims: reasonably; systemic: no |
| GLOW blend | Blend | None as a blend | No |
| Epitalon | Peptide | Minimal | No |
| NAD+ precursors | Small molecule | Biomarker/safety trials | Outcomes: not yet |
| SS-31 | Peptide (drug candidate) | RCTs, multiple indications | For specific indications: partially — mixed |
Notice that the popularity ranking and the evidence ranking are almost inverses. GHK-Cu, with the best skin evidence, is the least hyped; Epitalon, with the least, is among the most.
The honest bottom line
Nothing in this category is proven to slow aging in humans. GHK-Cu has real topical dermatology research; SS-31 has real clinical trial history in specific conditions; the rest is early-stage or mechanistic. That is not a dismissal — it is the current state of the science, and it is more interesting than the marketing.
Where to go next: GHK-Cu deep dive, the peptide comparison tool, the verified study library, and the Academy lesson on reading research.
This guide is for educational and research purposes only. Nothing here is medical advice or a recommendation to use any compound in humans.
Related guides.
GHK-Cu: The Copper Peptide Your Body Already Makes
GHK-Cu occurs naturally in plasma and declines with age. Here's what studies show on skin, collagen, and wound research.
BPC-157: What the Research Actually Says
An honest look at BPC-157 studies — tendon, gut, and angiogenesis findings, what's preclinical, and where the evidence stops.
CJC-1295 + Ipamorelin: What the Research Shows
CJC-1295 and Ipamorelin are studied together for growth hormone release. Here is what the published research actually shows.
TB-500: What the Research Actually Says
TB-500 promotes cell migration and wound healing in animal studies. Here's what published research shows — and where it stops.
MOTS-c: The “Exercise Mimetic” Peptide Getting Longevity Reddit Excited
MOTS-c is the mitochondrial peptide longevity Reddit calls an exercise mimetic. Here is what the research on MOTS-c actually shows, mostly in mice so far.
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