Letters from a Dermatologist · Ingredients
Peptides vs. Proteins: The Tiny Messages in Your Skincare
You flip a jar over and the label reads like a chemistry quiz: hydrolyzed protein, palmitoyl pentapeptide, acetyl hexapeptide. Is your moisturizer secretly a protein shake?
Here's what those names on the label actually mean.
Beads on a String
Start with amino acids. Think of them as beads. Snap a few together and you get a peptide, a short chain. Link hundreds of beads, let the chain fold into a shape, and you have a protein.
The prefixes are just numbers: tri means three, penta means five, and hexa means six. So a "pentapeptide" is a five-bead chain.
The "Hydrolyzed Protein" Line
"Hydrolyzed vegetable protein" is a large plant protein that has been broken down into smaller pieces, mostly short peptides. These short peptides help skin feel soft and smooth. In one human study, skin treated with small keratin peptides extracted from wool was more hydrated and more elastic than nearby skin that received no peptide. The treated skin also held water better.
Your Skin Is Made of Protein
The cells in your outer layer are packed with keratin, a tough protein woven into a network that gives the surface its strength. Deeper down, cells called fibroblasts make collagen, the protein that gives skin its support.
Your skin also deliberately breaks down one protein, filaggrin, into amino acids. Those amino acids become part of the skin's natural moisturizing factor, a built-in mix that keeps the surface supple.
Small Fragments, Big Messages
Collagen starts out as a longer molecule. After it leaves the cell, its ends are cut off. Researchers suspected that these cut-off pieces might work as signals that help control how much collagen gets made. In lab tests, part of one cut-off end did increase collagen production by fibroblasts. To find which part was doing the work, the researchers split that piece into smaller and smaller sections. The smallest section that still worked was only five amino acids long.
From the Lab to Real Faces
Attach a fatty acid called palmitoyl to that five-amino-acid peptide, and you get the palmitoyl pentapeptide you see on labels. In a 12-week study, 93 women applied the peptide moisturizer to one side of the face and an identical moisturizer without the peptide to the other. Measurements showed a bigger reduction in the look of fine lines and wrinkles on the peptide side. The women also rated their own lines as improved.
By the Numbers
Three Things to Try Tomorrow
- Count the beads. Tri-, penta-, and hexa- tell you how long the chain is.
- Spot the word "hydrolyzed." It means a large protein was broken into smaller pieces before going into the jar.
- Think in weeks. The facial study above ran 12 weeks of daily use. When you start a new cream, give it a couple of months before you judge it.
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