An activated ascorbic acid and compositions thereof are disclosed, especially such essentially anhydrous compositions as embody propylene glycol or a nonionic surface-active agent, which products have increased antioxidant activity in fats, oils, carotenoids, and fatty foods, especially in such materials as are exposed to oxidative stress. Further a method of stabilizing such materials and products against oxidative discoloration is disclosed wherein feeds and foodstuffs are stabilized with such composition, and a method of stabilizing a feed or foodstuff or flavoring with such an antioxidant composition, are all disclosed. Synergistic effects are obtained by the incorporation of a natural antioxidant, such as a Labiatae or tea extract, or a tocopherol therein, and antioxidant power and stabilization effectiveness is frequently further improved by inclusion therein of a second nonionic surface-active agent.