Collagen is the most important building block in the entire body. Collagen makes up 80% of connective tissue and 75% of skin, while most people sometimes think of the skin as an inert layer, it is actually in a constant state of change. In fact, the cells of the top layer, known as the epidermis, are completely renewing every two weeks. This layer has very low permeability that only small molecules can pass through, which is why most collagen creams and some beauty products are unable to penetrate it. While topical collagen creams help moisturize and reduce dryness and scaling, they do nothing to renew the structure beneath the skin.