Pet food comprising trisodium L-ascorbic acid-2-monophosphate (STAY-050) or sodium-calcium L-ascorbic acid-2-monophosphate (STAY-C35), or mixtures thereof and, optionally, a polymer (for fixation of the ascorbate on the dental surface) and use 5 thereof as additive to pet food for preventing or treating calculus, plaque, gingivitis and periodontal disease and for enhancing the antioxidative capacity in the whole organism.