Hyaluronic Acid also has many benefits and is one of the most interesting ingredients in skin care, specifically. Naturally found in the body, hyaluronic acid secures moisture and creates fullness—youthful skin naturally abounds with hyaluronic acid. Collagen is the most abundant protein in the human body and is the substance that holds the whole body together. It is found in the bones, muscles, skin and tendons, where it forms a scaffold to provide strength and structure.