Sustained release Ultra Vitamin C from Vitabiotics is formulate with 25mg of Citrus Bioflavonoids, to assist absorption. Immune & Nervous Systems Vitamin C contributes to the normal function of the immune and nervous systems and overall health Protection of Cells Vitamin C contributes to the protection of cells from oxidative stress. Ultra Vitamin C provides a daily source of vitamin C which is not produced or stored by the body. Collagen Synthesis Vitamin C contributes to normal collagen formation for the normal function of bones, teeth, cartilage, skin and blood vessels. Iron Absorption Vitamin C increases iron absorption and contributes to normal energy release.