There are a number of different types of collagen; the most prevalent two in the human body are types i and iii. In fact, type i collagen is the most abundant protein in the human body - it is present in almost every type of tissue.1 bone contains almost exclusively type i collagen. The collagen network in bone confers structural strength to bone tissue and prevents bone fragility. Deficient or defective collagen production, as can occur with aging, is a risk factor for fractures and other bone deformities. Type i collagen is also the major protein found in skin connective tissue where it is responsible for providing skin with its tensile strength and resiliency. Type iii collagen is found at high levels in cardiovascular tissue and also in newly developing skin. It is essential for the proper development of the cardiovascular system and skin tissue. Types i and iii collagen are often found together in the same tissues, as each form complements the structural integrity of the other. Vitamin c is required for the synthesis of collagen and participates at nearly every step of the process.