In the United States the Recommended Dietary Allowance for vitamin C is 90 mg per day for adult men and 75 mg per day for adult non-pregnant women.
Many potentially harmful effects have been attributed to excessive intakes of ascorbic acid, but the frequency of recorded toxicity is quite low.
A number of toxicity symptoms and signs have been attributed to large intakes of ascorbic acid by humans and laboratory animal.
These include, oxaluria, uricosuria, hypoglycemia, excessive absorption of iron, diarrhea, and allergic response, destruction of vitamin B12, and interference with hepatic mixed function oxidase systems.
Oxalic acid is an end product of normal ascorbic acid metabolism. Excessive intake of vitamin C may produce oxalate kidney stones, although this may occur only in persons predisposed to oxalate stone formation.
Excess vitamin C can promote repetitive free radical generation by iron. In the presence of iron overload, can mobilize such an enormous amount of iron from high body iron stores that the binding capacity of iron-binding proteins is over-whelmed and potentially lethal free iron is released into circulation.
Large doses have been consistently observed in humans are gastrointestinal disturbances and diarrhea occurring at leave intake nearly 20-80 times the RDA.
Ascorbic acid toxicity
