The present invention provides an antioxidant, an ROS inhibitor, an antioxidant enzyme production promoter, an antioxidant cosmetic, a UV care cosmetic, a prophylactic or therapeutic agent for gastrointestinal tract inflammation, and an antioxidant food or beverage, each containing an enzymatically synthesized glycogen (ESG) or an α-amylase digest (RG) thereof, as well as use for enhancing an antioxidative effect in vivo.
