|Vitamins C and E: beneficial effects from a mechanistic perspective.
|Year of Publication
|Traber MG, Stevens JF
|Free Radic Biol Med
|2011 Sep 01
|Animals, Antioxidants, Ascorbic Acid, Cytoprotection, Energy Metabolism, Free Radicals, Humans, Hypoxia-Inducible Factor 1, Inflammation, Neoplasms, Randomized Controlled Trials as Topic, Vitamin E
The mechanistic properties of two dietary antioxidants that are required by humans, vitamins C and E, are discussed relative to their biological effects. Vitamin C (ascorbic acid) is an essential cofactor for α-ketoglutarate-dependent dioxygenases. Examples are prolyl hydroxylases, which play a role in the biosynthesis of collagen and in down-regulation of hypoxia-inducible factor (HIF)-1, a transcription factor that regulates many genes responsible for tumor growth, energy metabolism, and neutrophil function and apoptosis. Vitamin C-dependent inhibition of the HIF pathway may provide alternative or additional approaches for controlling tumor progression, infections, and inflammation. Vitamin E (α-tocopherol) functions as an essential lipid-soluble antioxidant, scavenging hydroperoxyl radicals in a lipid milieu. Human symptoms of vitamin E deficiency suggest that its antioxidant properties play a major role in protecting erythrocyte membranes and nervous tissues. As an antioxidant, vitamin C provides protection against oxidative stress-induced cellular damage by scavenging of reactive oxygen species, by vitamin E-dependent neutralization of lipid hydroperoxyl radicals, and by protecting proteins from alkylation by electrophilic lipid peroxidation products. These bioactivities bear relevance to inflammatory disorders. Vitamin C also plays a role in the function of endothelial nitric oxide synthase (eNOS) by recycling the eNOS cofactor, tetrahydrobiopterin, which is relevant to arterial elasticity and blood pressure regulation. Evidence from plants supports a role for vitamin C in the formation of covalent adducts with electrophilic secondary metabolites. Mechanism-based effects of vitamin C and E supplementation on biomarkers and on clinical outcomes from randomized, placebo-controlled trials are emphasized in this review.
|Free Radic. Biol. Med.
|PubMed Central ID
|R01 DK081761-01A1 / DK / NIDDK NIH HHS / United States
R01 DK067930 / DK / NIDDK NIH HHS / United States
HL081721 / HL / NHLBI NIH HHS / United States
DK067930 / DK / NIDDK NIH HHS / United States
R01 HL081721 / HL / NHLBI NIH HHS / United States
R01 DK067930-04 / DK / NIDDK NIH HHS / United States
DK081761 / DK / NIDDK NIH HHS / United States
R01 DK081761 / DK / NIDDK NIH HHS / United States
R01 HL081721-05 / HL / NHLBI NIH HHS / United States