Vitamin C Research Today is a free monthly online journal that collates and summarizes the latest research about Vitamin C, including details on benefits, dosage, supplements, information.

Oral high dose ascorbic acid treatment for one year in young CMT1A patients: a randomised, double-blind, placebo-controlled phase II trial.

Verhamme C, de Haan RJ, Vermeulen M, Baas F, de Visser M, van Schaik IN

Department of Neurology and Clinical Neurophysiology, Academic Medical Centre, University of Amsterdam, PO Box 22660, 1100 DD, Amsterdam, The Netherlands. c.verhamme@amc.uva.nl

BACKGROUND: High dose oral ascorbic acid substantially improved myelination and locomotor function in a Charcot-Marie-Tooth type 1A mouse model. A phase II study was warranted to investigate whether high dose ascorbic acid also has such a substantial effect on myelination in Charcot-Marie-Tooth type 1A patients and whether this treatment is safe. METHODS: Patients below age 25 years were randomly assigned to receive placebo or ascorbic acid (one gram twice daily) in a double-blind fashion during one year. The primary outcome measure was the change over time in motor nerve conduction velocity of the median nerve. Secondary outcome measures included changes in minimal F response latencies, compound muscle action potential amplitude, muscle strength, sensory function, Charcot-Marie-Tooth neuropathy score, and disability. RESULTS: There were no significant differences between the six placebo-treated (median age 16 years, range 13 to 24) and the five ascorbic acid-treated (19, 14 to 24) patients in change in motor nerve conduction velocity of the median nerve (mean difference ascorbic acid as opposed to placebo treatment of 1.3 m/s, confidence interval -0.3 to 3.0 m/s, P = 0.11) or in change of any of the secondary outcome measures over time. One patient in the ascorbic acid group developed a skin rash, which led to discontinuation of the study medication. CONCLUSION: Oral high dose ascorbic acid for one year did not improve myelination of the median nerve in young Charcot-Marie-Tooth type 1A patients. Treatment was relatively safe. TRIAL REGISTRATION: Current Controlled Trials ISRCTN56968278, ClinicalTrials.gov NCT00271635.

Published 27 November 2009 in BMC Med, 7: 70.
Full-text of this article is available online (may require subscription).

Articles on Vitamin C published 25 November 2009:

Ascorbic acid for anemia management in hemodialysis patients: a systematic review and meta-analysis.   Am J Kidney Dis, 54(6): 1089-97.

BACKGROUND: Ascorbic acid is believed to improve anemia in patients with end-stage renal disease, but its overall effectiveness is unclear. STUDY DESIGN: Systematic review and meta-analysis. SETTING & POPULATION: Adult hemodialysis patients. SELECTION CRITERIA FOR STUDIES: Randomized clinical trials of ascorbic acid use in addition to standard anemia management. INTERVENTION: Ascorbic acid. OUTCOMES: Weighted mean difference (WMD) for change in hemoglobin level, recombinant human ... [Abstract] [Full-text]

Effect of vitamin C depletion on age-related hearing loss in SMP30/GNL knockout mice.   Biochem Biophys Res Commun, 390(3): 394-8.

Using senescence marker protein 30 (SMP30)/gluconolactonase (GNL) knockout (KO) mice, which cannot synthesize vitamin C (VC), we examined whether modulating VC level affects age-related hearing loss (AHL). KO and wild-type (WT) C57BL/6 mice were given water containing 1.5 g/L VC [VC(+)] or 37.5mg/L VC [VC(-)]. At 10 months of age, KO VC(-) mice showed significant reduction in VC level in the inner ear, plasma, and liver, increase in auditory brainstem response (ABR) thresholds, and decrease in ... [Abstract] [Full-text]

Articles on Vitamin C published 13 November 2009:

Effect of ascorbic acid in patients with Charcot-Marie-Tooth disease type 1A: a multicentre, randomised, double-blind, placebo-controlled trial.   Lancet Neurol, 8(12): 1103-10.

BACKGROUND: Charcot-Marie-Tooth disease type 1A (CMT1A) is a hereditary peripheral neuropathy that affects roughly one in 5000 births. No specific therapy currently exists for this degenerative disorder, which is characterised by distal progressive muscle atrophy and sensory loss, although ascorbic acid has been shown to reduce demyelination and improve muscle function in a transgenic mouse model of CMT1A. We tested the safety and efficacy of ascorbic acid in adults with CMT1A. METHODS: This ... [Abstract] [Full-text]

Articles on Vitamin C published 3 November 2009:

Importance of the conserved lysine 83 residue of Zea mays cytochrome b(561) for ascorbate-specific transmembrane electron transfer as revealed by site-directed mutagenesis studies.   Biochemistry, 48(44): 10665-78.

Cytochromes b(561), a novel class of transmembrane electron transport proteins residing in a large variety of eukaryotic cells, have a number of common structural features including six hydrophobic transmembrane alpha-helices and two heme ligation sites. We found that recombinant Zea mays cytochrome b(561) obtained by a heterologous expression system using yeast Pichia pastoris cells could utilize the ascorbate/mondehydroascorbate radical as a physiological electron donor/acceptor. We found ... [Abstract] [Full-text]

Simultaneous electrochemical determination of uric acid, dopamine, and ascorbic acid at single-walled carbon nanohorn modified glassy carbon electrode.   Biosens Bioelectron, 25(4): 940-3.

Single-walled carbon nanohorn modified glassy carbon electrode (SWCNH-modified GCE) was first employed for the simultaneous determination of uric acid (UA), dopamine (DA), and ascorbic acid (AA). The SWCNH-modified GCE displayed excellent electrochemical catalytic activities. The oxidation overpotentials of UA, DA, and AA decrease significantly and their oxidation peak currents increase dramatically at SWCNH-modified GCE. Linear sweep voltammetry (LSV) was used for the simultaneous ... [Abstract] [Full-text]

Articles on Vitamin C published 27 October 2009:

Antioxidants and aging: NMR-based evidence of improved skeletal muscle perfusion and energetics.   Am J Physiol Heart Circ Physiol, 297(5): H1870-5.

We sought to examine the potential role of oxidative stress on skeletal muscle function with advancing age. Nuclear magnetic resonance (NMR) was employed to simultaneously assess muscle perfusion (arterial spin labeling) and energetics ((31)P NMR spectroscopy) in the lower leg of young (26 + or - 5 yr, n = 6) and older (70 + or - 5 yr, n = 6) healthy volunteers following the consumption of either placebo (PL) or an oral antioxidant (AO) cocktail (vitamins C and E and alpha-lipoic acid), ... [Abstract] [Full-text]

Articles on Vitamin C published 5 October 2009:

Beta-catenin regulates vitamin C biosynthesis and cell survival in murine liver.   J Biol Chem, 284(41): 28115-27.

Because the Wnt/beta-catenin pathway plays multiple roles in liver pathobiology, it is critical to identify gene targets that mediate such diverse effects. Here we report a novel role of beta-catenin in controlling ascorbic acid biosynthesis in murine liver through regulation of expression of regucalcin or senescence marker protein 30 and L-gulonolactone oxidase. Reverse transcription-PCR, Western blotting, and immunohistochemistry demonstrate decreased regucalcin expression in ... [Abstract] [Full-text]

Articles on Vitamin C published 28 September 2009:

Ferritin-dependent radical generation in rat liver homogenates.   Toxicology, 264(3): 155-61.

The hypothesis of this study was that mammalian ferritin (FER) has the ability of releasing Fe in the tissue to catalyze the generation of free radicals, such as ascorbyl (A) and hydroxyl radical (OH), that might lead to the damage of FER itself. The rat liver homogenates exhibited an electron paramagnetic resonance (EPR) signal with the spectral features (a(H)=1.88 G, g=2.0054) of A. The addition to the reaction medium of isolated rat liver FER increased by 3-fold the EPR signal, as compared ... [Abstract] [Full-text]

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