Polysaccharide sugar derived from yeast or oats. It has some antioxidant properties and is a skin-soothing agent. Beta-glucan is considered an excellent ingredient for improving the look of redness and other signs of sensitive skin.
References for this information:
Phytotherapy Research, February 2014, pages 159-166
Journal of Drugs in Dermatology, February 2007, issue 2, pages 167-170