Vitamin C disease". Reviews state that "data from epidemiological studies do not support an association between excess ascorbic acid intake and kidney stone formation in apparently healthy individuals", although one large, multi-year trial did report a nearly two-fold increase in kidney stones in men who regularly consumed a vitamin C supplement. Recommendations for vitamin C intake by adults have been set by various national agencies: In 2000 the North American Dietary Reference Intake chapter on vitamin C updated the Recommended Dietary Allowance (RDA) to 90 milligrams per day for adult men and 75 mg/day for adult women, and set a Tolerable upper
Chemistry of ascorbic acid catalytically hydrogenated to sorbitol, which is then oxidized by the microorganism "Acetobacter suboxydans" to sorbose. Only one of the six hydroxy groups is oxidized by this enzymatic reaction. From this point, two routes are available. Treatment of the product with acetone in the presence of an acid catalyst converts four of the remaining hydroxyl groups to acetals. The unprotected hydroxyl group is oxidized to the carboxylic acid by reaction with the catalytic oxidant TEMPO (regenerated by sodium hypochlorite — bleaching solution). Historically, industrial preparation via the Reichstein process used potassium permanganate as the bleaching solution. Acid-catalyzed hydrolysis of this product