The present invention relates to ascorbic acid single-phase solution compositions that provide enhanced stability, enhanced solubility and an enhanced photoprotective effect as compared to prior compositions. The compositions comprise L-ascorbic acid; a cinnamic acid derivative such as p-coumaric acid, ferulic acid, caffeic acid, sinapinic acid, a derivative thereof, and a combination thereof; a solvent comprising a glycol ether and an alkanediol; and water; the composition having a pH of no more than about 3.5. The compositions may also comprise a form of Vitamin E and are useful for treatment of radical-induced damage to a subject, particularly the skin of a subject.