What it does
A peptide-based humectant that holds 4-5x more moisture than hyaluronic acid by weight. Sits on top of skin to form a hydrating film.
Best for
Dehydrated skin, layering under richer creams, anyone wanting plumping without the stickiness of pure hyaluronic acid.
The full picture
Polyglutamic acid is a relatively newer humectant gaining attention in K-beauty and Western formulations alike. It binds water much more efficiently than hyaluronic acid (the standing humectant champion) but works mostly on the surface, forming a moisture-retaining film rather than penetrating deeply. The two pair well: HA for deeper plumping, PGA for surface hydration and a softer-feeling finish. Found in Medik8 Pro-Collagen+ Peptide Cream and several newer K-beauty essences.
Evidence
PGA significantly improves skin hydration and elasticity in controlled trials.
Read the source: PubMed: polyglutamic acid hydration ->