Vitamin C foods. Among foods classified for mandatory fortification with vitamin C were fruit-flavored drinks, mixes, and concentrates, foods for a low-energy diet, meal replacement products, and evaporated milk. Ascorbic acid and some of its salts and esters are common additives added to various foods, mostly to retard oxidation. The relevant European food additive E numbers are: From the U.S. National Institutes of Health: [In humans] "Approximately 70%–90% of vitamin C is absorbed at moderate intakes of 30–180 mg/day. However, at doses above 1,000 mg/day, absorption falls to less than 50%." It is transported through the intestine via both glucose-sensitive and glucose-insensitive
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