Interaction among vitamin C, vitamin E, and beta-carotene

Abstract

The effects of vitamin C (ascorbic acid), vitamin E (alpha-tocopherol), and beta-carotene as antioxidants and their cooperative action against the oxidation of lipid in solution, membranes, and lipoproteins have been studied and reviewed. Ascorbic acid and alpha-tocopherol act as potent, and probably the most important, hydrophilic and lipophilic antioxidants, respectively. They function at their own site individually and furthermore act synergistically. beta-Carotene has lower reactivity toward radicals than does alpha-tocopherol and acts as a weak antioxidant in solution. It is more lipophilic than alpha-tocopherol and is assumed to be present at the interior of membranes or lipoproteins, which enables it to scavenge radicals within the lipophilic compartment more efficiently than does alpha-tocopherol. The cooperative interaction between vitamin C and vitamin E may be quite probable, that of vitamin C and beta-carotene is improbable, whereas that between vitamin E and beta-carotene may be possible.

Molecular detection of exercise-induced free radicals following ascorbate prophylaxis in type 1 diabetes mellitus: a randomised controlled trial

“…Davies and Timmins [46] showed rate constant reactions of <10 5 dm 3 mol −1 s −1 and 1.3× 10 7 dm 3 mol −1 s −1 for the interactions of α-tocopherol and ascorbic acid respectively with the L· radical. In addition, Niki et al [47] suggested that α-tocopherol cannot stabilise the alkoxyl radical before attacking polyunsaturated fatty acids, as the reaction rate constant for this interaction is relatively slow.…”

Beta Carotene Supplementation and Age-Related Maculopathy in a Randomized Trial of US Physicians

“…The observation that beta carotene is found only in trace amounts in the retina (25)(26)(27)(28) provides some indirect support for this possibility. Nevertheless, a possible indirect effect of beta carotene in the AREDS formulation, mediated through interaction with other trial ingredients (29)(30)(31), cannot be excluded.…”

Inflammation in the vascular bed: Importance of vitamin C

“…Ascorbate can also recycle vitamin E, or α-tocopherol, from its radical form (Niki et al, 1995). The importance of ascorbate recycling of α-tocopherol stems from properties of the latter as a lipophilic antioxidant, capable of interfering with atherogenic oxidative modification of LDL (Esterbauer et al, 1990;Thomas & Stocker, 2000).…”

“…This cooperative relationship has been shown to significantly decrease copper mediated LDL oxidation in vitro (Berliner & Heinecke, 1996;Esterbauer et al, 1990), down regulate expression of endothelial VEGF Rodriguez et al, 2005), and decrease production of reactive oxygen species though down regulation of vascular NADPH oxidase (Chen et al, 2001). While there is ample in vitro evidence that ascorbate spares α-tocopherol in plasma LDL (Frei et al, 1989;Niki et al, 1995), results are mixed as to whether ascorbate protects it in cells. Glascott and co-workers (Glascott, Jr. et al, 1996) found that there was no sparing of α-tocopherol by ascorbate in hepatocytes exposed to an oxidant stress generated by allyl alcohol.…”

“…Effect of Vitamin C: References Direct oxidation of LDL Prevents (Frei et al, 1989;Niki et al, 1995) Recycles α-tocopherol (Frei, 1991) Endothelial cell dysfunction Nitric oxide generation Enhances (Heller et al, 1999;Heller et al, 2001; (Schwartz et al, 1982) Monocyte/macrophages LDL uptake and modification Controversial (Stait & Leake, 1994) Inflammatory markers Inhibits (May et al, 2005b) Nitric oxide release Inhibits (Mizutani et al, 1998) …”