Vitamin C dietary supplementation, are people who consume more vitamin C at lower risk for developing cancer, and if so, does an orally consumed supplement have the same benefit? Second, for people diagnosed with cancer, will large amounts of ascorbic acid administered intravenously treat the cancer, reduce the adverse effects of other treatments, and so prolong survival and improve quality of life? A 2013 Cochrane review found no evidence that vitamin C supplementation reduces the risk of lung cancer in healthy people or those at high risk due to smoking or asbestos exposure. A second meta-analysis found no effect on the risk
Chemistry of ascorbic acid titration with an oxidizing agent, and several procedures have been developed. The popular iodometry approach uses iodine in the presence of a starch indicator. Iodine is reduced by ascorbic acid, and, when all the ascorbic acid has reacted, the iodine is then in excess, forming a blue-black complex with the starch indicator. This indicates the end-point of the titration. As an alternative, ascorbic acid can be treated with iodine in excess, followed by back titration with sodium thiosulfate using starch as an indicator. This iodometric method has been revised to exploit reaction of ascorbic acid with iodate and iodide in