In addition to being a naturally-occurring protein in the human body, collagen is also a popular skincare ingredient. According to the Mayo Clinic, exposure to ultraviolet (UV) light breaks down your skin's connective tissue—collagen and elastin fibers—which lie in the deeper layer of the skin (dermis). As it does, your skin may become less resilient, and the visible signs of aging—such as fine lines and wrinkles—may become more pronounced. Alongside elastin (another protein), it also helps keep...