Additiva Vitamin C is used to treat vitamin C deficiency in adults. Vitamin C is neither formed nor stored by the body. However, the vitamin is required for the entire metabolism and is also involved in complex, body-specific enzyme activities. Due to its important role in the activation of the metabolism of cells, the conversion of nutrients into body energy and the participation in numerous enzymatic processes, Vitamin C is essential for important tasks in the body, such as the maintenance of the immune system.