TKI is a blend of vitamins A and C that helps to maintain good health. Vitamin C has important roles in the body, including the prevention of free radical damage to DNA and the production of collagen, the primary structural protein in connective tissue. Collagen is also the main protein involved in wound healing, and deficiencies in vitamin C may lead to impaired healing of wounds.  Vitamin A contributes to skin health by helping to maintain the barrier function of skin cells.  It increases the proliferation of dividing cells in the epidermis, compacts the outer epidermal layer that consists of dead cells, and increases the number of glycosaminoglycans – polysaccharides that help hydrate the skin. Vitamin A helps maintain immune function by stimulating the development of immune cells, and deficiencies of vitamin A result in a decreased ability of macrophages to ingest and destroy bacteria.  The polyphenolic and flavonoid content in dandelions is three times greater in the leaves than the roots.