LearningHealth
Research area

Skin & collagen

Cosmetic and dietary peptides aimed at the skin matrix. Legal, low-risk, and the only group here with properly blinded trials you can read — including some that came out negative.

GHK-Cu

copper tripeptide-1, glycyl-L-histidyl-L-lysine copper(II), GHK
L3

A genuine human plasma peptide with a huge mechanistic literature and a surprisingly thin set of clinical trials.

Skin & collagen Cosmetic ingredient; not a drug

Matrixyl (pal-KTTKS)

palmitoyl pentapeptide-4, palmitoyl pentapeptide-3, pal-KTTKS, Matrixyl
L4

A fragment of procollagen that signals "make more collagen". The best-designed cosmetic peptide trial in this collection tested it.

Skin & collagen Cosmetic ingredient; not a drug

Argireline

acetyl hexapeptide-8, acetyl hexapeptide-3, Ac-EEMQRR-NH₂
L4

Marketed as "topical Botox". The mechanism is real, the potency comparison is misleading, and two randomised trials are positive.

Skin & collagen Cosmetic ingredient; not a drug

Collagen peptides

hydrolysed collagen, collagen hydrolysate, gelatin hydrolysate, collagen tripeptide
L5

The one peptide here with dozens of randomised trials — and a 2025 meta-analysis arguing the positive results come from the weaker studies.

Skin & collagen Food / dietary supplement
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