The effects of ascorbic acid toxicity

Overdoses of vitamin C induce perspiration, nervous tension, and lowered pulse rate, WHO recommends that daily intake be less than 0.15 mg/kg.

Massive doses of vitamin C have been shown to reduce serum vitamin B12 levels. In part, this may be due to an effect of ascorbic acid on vitamin B12 in food.

Ascorbic acid destroys B12 in food. Ascorbic acid also inhibits the utilization of beta-carotene.

Some individuals, exhibit accelerated conversion of ascorbic acid to oxalate, probably through greater inducibility of enzymes in the ascorbate-oxalate pathway.

The hyperoxaluria of these individuals, following large doses of vitamin C, increases the risk of urinary stone formation.

Excessive doses of vitamin C can cause diarrhea but the effect is not long lasting. The large excess of vitamin C is promptly excreted in the urine but may cause uricosuria and increased absorption of iron, with the potential for iron reloaded.

Although toxicity is rare, the tolerable upper intake level established by the food and Nutrition Board (FNB) of the Institute of Medicine for vitamin C in adults was set at 2000 mg.
The effects of ascorbic acid toxicity

Toxicity of ascorbic acid

The amount of ascorbic acid in various tissues of the body varies markedly, probably depending on how those tissues use the ascorbic acid. It has been purported to be a prophylactic or treatment for the common cold as well as for cancer.

Ascorbic acid is a water-soluble vitamin and is not usually stored. Thus, there is little evidence of toxicity.

Still, many potentially harmful effects have been attributed to excessive intakes of ascorbic acid, but the frequency of recorded toxicity is quite low.

Excess ascorbic acid intakes in humans and laboratory animals have been reported to produce a variety of toxic signs or symptoms including allergic responses, oxaluria, uricosuria and interference with mixed- function oxidase systems.

Although some investigators have suggested that megadoses of ascorbic acid may be a risk factor in renal oxalate stores, urinary oxalate levels do not change with increasing intakes of ascorbate.

Ascorbic acid toxicity also found to produce rebound scurvy among infants and pregnant women.
Toxicity of ascorbic acid