A Cochrane review [Abstract] 1 included 6 study with a total of 702 subjects. They compared the effect of oral ascorbic acid (1 to 4 grams) and placebo treatment in Charcot-Marie-Tooth disease type 1A (CMT1A). In 5 trials the adults with CMT1A (n= 622) received ascorbic acid or placebo. Ascorbic acid did not improve the course of CMT1A as measured by the CMT neuropathy score (0 to 36 scale) at 12 months (MD -0.37; 95% CI -0.83 to 0.09; 5 studies; n = 533), or at 24 months (MD -0.21; 95% CI -0.81 to 0.39; 3 studies; n = 388). Ascorbic acid treatment showed a positive effect on the nine-hole peg test versus placebo (MD -1.16 seconds; 95% CI -1.96 to -0.37), but the clinical significance of this result is probably small. Meta-analyses of other secondary outcome parameters showed no relevant benefit of ascorbic acid. In one trial, 80 children with CMT1A received ascorbic acid or placebo. The trial showed no clinical benefit of ascorbic acid treatment. Adverse effects did not differ in their nature or abundance between ascorbic acid and placebo.
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