Does vitamin C supplementation influence the levels of circulating oxidized LDL, sICAM-1, sVCAM-1 and vWF-antigen in healthy male smokers?

Abstract

Objective: To examine the effects of vitamin C supplementation on the concentration of oxidation markers, in particular, circulating oxidized LDL (OxLDL) and on endothelial activation markers. Design: Randomized double-blind, placebo-controlled crossover trial. Setting: Belgian population of the city of Leuven. Subjects: A total of 34 healthy male smokers aged 26-73 y. Intervention: Smokers were randomly assigned to receive either vitamin C (250 mg twice daily) or placebo capsules, each to be taken for 4 weeks. After a 1-week washout period, participants then crossed over to the alternative capsules for further 4 weeks. Mean outcome measures: Markers of oxidation (bilirubin, uric acid, a-tocopherol, retinol, malondialdehyde, circulating Oxidized LDL (OxLDL)) and markers of endothelial activation (sICAM-1, sVCAM-1, vWF-antigen) were analysed. Results: Plasma ascorbate concentrations significantly increased from 46.6717.6 to 70.1721.2 mmol/l after a 4-week treatment with 500 mg vitamin C per day. The other plasma antioxidants concentrations, including bilirubin, uric acid, a-tocopherol and retinol, were similar in both treatment periods. Vitamin C did not change plasma malondialdehyde and circulating OxLDL compared with placebo (vitamin C 0.7370.25 mg/dl OxLDL; placebo 0.7270.21 mg/dl OxLDL). After vitamin C supplementation, neither sICAM-1 and sVCAM-1 levels nor the concentration of vWF-antigen significantly differed from placebo condition. Conclusions: Oral supplementation of vitamin C is not associated with changes in markers of oxidation or endothelial activation in healthy male smokers.

Smoking, Oxidative Stress and Cardiovascular Diseases-Do Anti-Oxidative Therapies Fail?

“…In another small study (8 participants), however, application 1 g of vitamin C per day did not improve smoking-caused alterations of FMD [110]. Similarly, in a study of 34 healthy male smokers, intake of 250 mg of vitamin C twice a day did not reduce serum soluble adhesion molecules or markers of oxidation (malondialdehyde, oxLDL) [111]. However, in a combination study comprising 44 smokers who received 60 mg of vitamin C or 60 mg of vitamin C plus 480 mg Enzogenol (a flavonoid extract from Pinus radiata) per day for 12 weeks, vitamin C alone improved FMD.…”

Effects of dietary factors on oxidation of low-density lipoprotein particles

“…While some studies found that ascorbic acid supplementation was associated with a reduction of the susceptibility of LDL particles to oxidation [80,81], another study failed to find an effect of ascorbic acid supplementation (at least 500 mg/day) [63]. Moreover, one study failed to find a significant effect of ascorbic acid supplementation on circulating LDL concentrations [82]. Even if ascorbic acid is water soluble and is not incorporated in LDL particles, it has been proposed that this vitamin may prevent LDL particle oxidation by scavenging free radicals and other reactive species in aqueous milieu [76].…”

The influence of vitamin C on systemic markers of endothelial and inflammatory cell activation in smokers and non-smokers

“…We also extend the studies of Tousoulis et al [65] and Van Hoydonck et al [67] by examining two other major inflammatory molecules, (i) neutrophil elastase, a marker of neutrophil activation, and (ii) neopterin, a marker of monocyte activation. There was no statistically significant difference in neopterin or elastase concentrations between smokers and non-smokers at baseline.…”