Vitamin A hugely supports the skin’s immune system, fighting harmful bacteria, pollutants, and infections. It also assists in maintaining a healthy dermis and epidermis, the top two layers of your skin. In fact, vitamin A skin treatments work to promote and maintain a healthy dermis and epidermis, the top two layers of the skin. By strengthening the skin barrier, this powerful vitamin protects the skin from harmful irritants that attempt to attack and harm the surface.