A randomized, double-blind, placebo-controlled trial of supplementary vitamins E, C and their combination for treatment of haemodialysis cramps

Abstract

Background. Muscle cramps that improve after carnitine or vitamin E therapies are common in haemodialysis (HD) patients. Because vitamin C participates in carnitine biosynthesis, and its levels are reduced in uraemia, subclinical vitamin C depletion may contribute to HD cramps. Our aim was to determine the effects of vitamins C, E and their combination on the frequency and intensity of HD cramps. Methods. In this placebo-controlled, double-blind study, 60 HD-patients were randomized into four therapeutic groups. Each group (n=15) received six identical capsules daily for 8 weeks, containing one of the following: vitamin E (400 mg), vitamin C (250 mg), their combination, or placebo. Results. The frequency and intensity of HD cramps decreased significantly in all three vitamin groups compared with the placebo group at the end of the trial, and compared with the pre-treatment values. At the end of the trial, vitamins E, C, their combination, and placebo produced cramp reductions of 54, 61, 97 and 7%, respectively. The percentage cramp reduction had no significant correlation with age, sex, aetiology of end-stage renal disease, serum electrolytes or HD duration, but showed a positive correlation (r=0.33, P=0.01) with the type of therapy. No vitamin-related adverse effects were encountered during the trial. Conclusion. Short-term treatment with the combination of vitamins E and C is safe and effective in reducing HD cramps; however, its safety for prolonged therapy has yet to be evaluated in HD patients.