Collagen is the most important structural protein in the skin which supports connective tissue and maintains skin thickness. By age 25 the average person has begun losing 1% of their skin’s collagen per year. By age 40 some people have lost nearly 25% of their total collagen, and this accelerates to 1.5% loss each year after that. The skin then becomes thinner, drier, and less elastic which contributes to visible signs of aging.