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| The Importance of Vitamin C |
METABOLISM AND EXCRETION
The fate of vitamin C depends on demand, route of administration and dose supplied. In all
species initial metabolism involves the conversion of ascorbic acid to dehydroascorbic
acid. In the guinea pigs this is delactonised to diketoglutaric acid, which is then
decarboxylated to produce carbon dioxide and other products. Exhalation of CO2 is a major
route of elimination in the guinea pig, other routes being the faeces and urine.
TOXICITY
Excess vitamin C is rapidly eliminated through faeces, urine and expired air, and is
deemed relatively non-toxic. However, persistently high intakes may lead to diarrhoea
(osmotic effect of carbohydrate within the intestine) or the formation of kidney stones
(oxalic acid). In addition blood and urine tests that rely on oxidation-reduction
reactions may be affected. |
