A short-chain sugar produced enzymatically from plant sucrose and maltose. Where a postbiotic delivers the useful fragments of bacteria, a prebiotic takes the opposite approach: it is food — a carbohydrate selected because the skin’s beneficial resident bacteria can metabolise it more readily than the problematic ones can.
How it works
The skin’s surface hosts a stable community of microorganisms that competes for space and nutrients. Research on alpha-glucan oligosaccharide has associated it with selectively supporting beneficial residents such as Staphylococcus epidermidis over less desirable colonisers — shifting the competitive balance by feeding one side. A balanced surface community, in turn, is linked with a better-maintained barrier and a less reactive skin state.
Because it is a sugar, it also behaves as a mild humectant, holding a little water at the surface.
In formulation
Appears in microbiome-positioned masks, moisturisers and cleansers, often paired with a ferment or lysate so that the prebiotic and postbiotic approaches work together. It is gentle, non-exfoliating and non-photosensitising, with no meaningful sensitivity concerns of its own.
What to expect
Like most microbiome ingredients, its case is built on the ecosystem rather than the instant result — the visible payoff is skin that stays comfortable and even-tempered over time.
