The role of vitamins and supplements on skin appearance.

Skin appearance is affected by intrinsic factors (eg, aging) and extrinsic factors (eg, UV light). A myriad of treatments has been created to combat the phenotypic effects of these forces, including vitamins and supplements. This article reviews these therapies with a focus on carotenoids; vitamins C, E, and D; as well as collagen, ceramides, and mixed supplements.