Oat has one of the longest histories of any skincare ingredient, and unusually for a traditional remedy, a reasonable body of modern evidence behind it.
The active constituents
Oat's effects are attributed to several groups of compounds rather than one. Avenanthramides are polyphenols largely unique to oats, studied for their antioxidant activity and for reducing the appearance of redness. Beta-glucan is a polysaccharide that forms a hydrating film on the skin surface. Oat also contains saponins with mild cleansing properties, and lipids and proteins that contribute to its emollient feel.
How it works
Research associates avenanthramides with reduced inflammatory signalling and with an effect on the itch response. Beta-glucan works more simply, holding water at the surface and reducing the rate at which it evaporates.
Colloidal oatmeal versus oat extract
Worth distinguishing, because the names are used loosely.
Colloidal oatmeal is finely milled whole oat, and in the United States it is a recognised over-the-counter skin protectant with a defined monograph. Oat kernel extract is a solvent extraction of specific constituents from the kernel. They are related but not equivalent, and only colloidal oatmeal carries that regulatory recognition.
A product listing oat kernel extract is using a cosmetic ingredient, not a monographed skin protectant.
Gluten
Oats do not naturally contain gluten but are frequently contaminated with it during growing and processing. For coeliac disease, this matters for ingestion rather than topical application, as gluten is not absorbed through intact skin. People with a separate wheat allergy may still react topically.
