Acetyl Carnosine is a natural imidazole-containing dipeptide that has antioxidant activities in cells, particularly against lipid peroxidation. Formulations containing Acetyl Carnosine may prevent or resolve cataracts when added to the eyes of animals, presumably through the conversion of NAC to another antioxidant, carnosine. Acetyl Carnosine and related dipeptides, delivered in specific formulations, may also have protective effects for skin. N-Acetyl-L-carnosine is used to treat cataracts and to treat UV-induced immunosuppression.