The physiological role of dehydroascorbic acid

Abstract

Dehydroascorbic acid (DHA) is abundant in the human diet and also is generated from vitamin C (ascorbic acid, AA) in the lumen of the gastrointestinal tract. DHA is absorbed from the lumen of the small intestine and reduced to AA, which subsequently circulates in the blood. Utilization of AA as an antioxidant and enzyme cofactor causes its oxidation to DHA in extracellular £uid and cells. DHA has an important role in many cell types because it can be used to regenerate AA. Both physiological (e.g. insulin, insulin-like growth factor I, cyclic AMP) and pathological (e.g. oxidative stress, diabetes, sepsis) factors alter the transport and metabolic mechanisms responsible for this DHA recycling. ß 2002 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.

Adverse effects of antioxidative vitamins

“…Also, vitamin C has a slightly stimulating activity, so its night-time taking is not recommended [2,4]. A range of adverse effects are induced by the oxidized form of vitamin C (formed in high concentrations when the reduced form of this vitamin is intensively, oxidative stress-dependently expended) [15,44,84]. It can lead to the inhibition of the transport of different substances and the impairment of some metabolic processes.…”

Vitamin C in the Treatment and/or Prevention of Obesity

“…Several relevant functions have been ascribed to VC: wound healing, iron absorption collaboration, collagen biosynthesis participation, and hemoglobin activation (40). Besides, this vitamin acts as an enzymatic cofactor for the biosynthesis of collagen, carnitine, cathecolamines, and peptide neurohormones (41). However, the most acclaimed feature of this molecule relies on its antioxidant properties, since it has been reported that plasma and cell VC acts as a potent oxygen and nitrogen free radical scavenger (37).…”

Protective effects of vitamin C against biochemical toxicity induced by malathion pesticides in male albino rat

“…Vita- min C is an important water-soluble chain-breaking antioxidant and enzyme cofactor (Wilson, 2002). Supplementation with vitamin C (500 or 1000 mg/day) during 13 weeks in 48 healthy men and women, has shown to increase the lymphocyte ascorbate by 51%, accompanied by an increase of lymphocyte glutathione by 18% (Lenton et al, 2003).…”