Original ContributionHigh-dose vitamin C supplementation increases skeletal muscle vitamin C concentration and SVCT2 transporter expression but does not alter redox status in healthy males
Section snippets
Subjects
Healthy male participants (n=8) ages 18–40 years were recruited for the study through local community- and university-wide advertising. Potential participants completed a prior medical screening session and questionnaire to rule out any cardiovascular, pulmonary, renal, or metabolic disease. Individuals were excluded if they were smokers, if they suffered from a bleeding disorder or heart murmur, if they were highly trained athletes, or if they were consuming any vitamin supplements. This study
Participants
All eight enrolled participants completed the trial as outlined. Participants were aged 25.9±2.3 years and had a mean height and weight of 178.9±3.8 cm and 81.8±4.2 kg, respectively. Baseline plasma vitamin C concentrations of participants were 58.1±6.7 µmol/L, and skeletal muscle concentrations were 2.9±0.2 mg/100 g wet weight. All participants had adequate baseline plasma vitamin C concentrations according to plasma cutoff levels reported by Jacob and Sotoudeh [37]. Baseline skeletal muscle
Discussion
A major finding of the present study was that 7 days of supplementation with vitamin C (500 mg twice daily) was required for vitamin C concentrations in skeletal muscle to significantly increase in healthy males with adequate baseline vitamin C concentrations. Vitamin C concentration did not increase further in skeletal muscle after 7 days of vitamin C supplementation, although the increase compared to placebo was greatest (~1.3 times placebo) at 42 days. In contrast, plasma vitamin C was more
Acknowledgments
We gratefully thank our medical doctor, Dr. Andrew Garnham, for his medical support and consultation throughout the trial, as well as for performing all muscle biopsy and blood collection procedures.
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2016, Free Radical Biology and MedicineCitation Excerpt :Unfortunately, there is a paucity of studies specifically investigating effects of chronic vitamin C supplementation in isolation of other antioxidants on force production during exercise in healthy individuals. Moreover, given that it might take up to seven days of supplementation with high dose oral vitamin C (1 g/day) to significantly increase muscle vitamin C concentrations [131], it is unclear what effect an acute dose would have in muscle. Acute vitamin C infusion (2 g) was shown to improve knee extensor fatigue resistance during repetitive exhaustive knee extensions in patients with chronic obstructive pulmonary disease (COPD), as demonstrated by improved maintenance of maximal and magnetic femoral nerve stimulated knee extensor force production [136].