Glossary
Short chains of amino acids (2-50 amino acids long) used in skincare to signal skin cells to perform specific functions: stimulating collagen production, reducing muscle contraction (reducing expression lines), strengthening the barrier, or providing antimicrobial defense.
Peptides are fragments of proteins. Collagen, for example, is a protein made of long chains of amino acids. When collagen breaks down (from UV damage, aging, or enzymes), it produces peptide fragments. These fragments act as signals to fibroblasts: "Collagen has been broken down here; produce more." Skincare peptides exploit this signaling system by applying synthetic versions of these signal fragments to tell fibroblasts to increase collagen production even when no actual breakdown has occurred.
Signal peptides (Matrixyl/palmitoyl tripeptide-1, Matrixyl 3000): Tell fibroblasts to produce more collagen and elastin. The most well-studied category with genuine clinical evidence of wrinkle reduction. Carrier peptides (copper peptides/GHK-Cu): Deliver trace minerals (copper) to skin cells to support enzymatic processes involved in wound healing and collagen synthesis. Copper peptides also have antioxidant and anti-inflammatory properties. Neurotransmitter-inhibiting peptides (Argireline/acetyl hexapeptide-3): Reduce the release of neurotransmitters that cause muscle contraction, theoretically reducing expression lines through a mechanism similar to (but much milder than) botulinum toxin. Antimicrobial peptides (AMP): Kill bacteria and fungi, relevant to acne management and wound care.
Signal peptides (particularly Matrixyl) have the strongest clinical evidence: multiple studies demonstrate measurable collagen increase and wrinkle reduction with consistent use over 8 to 12 weeks. The effects are real but modest compared to retinoids or professional treatments. Peptides work best as part of a comprehensive anti-aging routine, not as a standalone miracle ingredient.
Different, not better. Retinol has stronger evidence and more dramatic effects on collagen, cell turnover, and overall skin renewal. Peptides are gentler, have no irritation period, and can be used by people who cannot tolerate retinoids. Many dermatologists recommend using both: retinol at night for heavy lifting, peptides in the morning for supplemental stimulation.
Peptide penetration depends on molecular size and delivery technology. Small peptides (2-5 amino acids) penetrate the stratum corneum reasonably well. Larger peptides may need delivery enhancement (liposomal encapsulation, fatty acid conjugation like palmitoylation). Product formulation quality significantly affects whether the peptides reach their target cells.
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