Urinary excretion of vitamin C depends on body stores, intake and renal function.Ascorbic acid has been found to be involved in a number of biochemical processes.
Since this change takes place readily, vitamin C is very susceptible to destruction through oxidation, which is accelerated by heat and light.
Reversible oxidation-reduction of ascorbic acid with dehydroascorbic acid is the most important chemical property of vitamin C and the basis for its known physiological activities and stabilities (Moser and Bendich, 1991).
In guinea pigs, rats, and rabbits, CO2is the major excretory mechanism for vitamin C.
Primates do not normally utilize the CO2 catabolic pathway, with the main loss occurring in the urine.
6-1), slightly soluble in acetone and lower alcohols.
A 0.5% solution of ascorbic acid in water is strongly acid with a p H of 3.Vitamin C is the least stable and, therefore, most easily destroyed of all the vitamins.Metabolic need for ascorbic acid is a general one among species, but a dietary need is limited to humans, subhuman primates, guinea pigs, fruit-eating bats, some birds (including the red-vented bulbul and related Passeriformes species), insects, fish (such as coho salmon, rainbow trout, and carp), and perhaps certain reptiles (Mc Dowell, 2000).The most clearly established functional role for vitamin C involves collagen biosynthesis.Beneficial effects result from ascorbic acid in the synthesis of “repair” collagen.In its metabolism, ascorbic acid is first converted to dehydroascorbate by several enzymes or nonenzymatic processes and can then be reduced back to ascorbic acid in cells (Johnston et al., 2007).Absorbed vitamin C readily equilibrates with the body pool of the vitamin.Vitamin C occurs in two forms, namely L-ascorbic acid (reduced form) and dehydro-L-ascorbic acid (oxidized form).Although in nature the vitamin is primarily present as ascorbic acid, both forms are biologically active.In experimental animals, highest concentrations of vitamin C are found in the pituitary and adrenal glands, and high levels are also found in the liver, spleen, brain and pancreas.Vitamin C also tends to localize around healing wounds.