Cross-over study of influence of oral vitamin C supplementation on inflammatory status in maintenance hemodialysis patients

BACKGROUND Both vitamin C deficiency and inflammation are prevalent in maintenance hemodialysis (MHD) patients. In this study, we aimed to elucidate the effect of oral vitamin C supplementation on inflammatory status in MHD patients with low vitamin C level and high hypersensitive C-reactive protein (hs-CRP) level. METHODS A total of 128 patients were recruited in our present study. Patients were divided into two groups. In group 1 (n = 67), patients were orally administered with 200 mg/day vitamin C in the first 3 months, and then the vitamin C supplementation was withdrawn in the next 3 months. In group 2 (n = 61), patients were not given vitamin C in the first 3 months, and then they were orally administered with 200 mg/day in the next 3 months. Levels of hs-CRP, prealbumin, albumin and hemoglobin as well as the EPO resistance index (ERI) were determined at the baseline and every 3 months throughout the study. Plasma vitamin C level was determined by high-performance liquid chromatography with UV detection. RESULTS Among the 128 patients, 28 of them dropped out of the study before completion. Consequently, a total of 100 patients (group 1: n = 48; group 2: n = 52) were included in the final analysis. At the baseline, the plasma vitamin C level of all patients was less than 4 μg/mL. However, this proportion was decreased to 20% after the vitamin C supplementation for 3 months. Compared with patients without the vitamin C supplementation, a decreased level of hs-CRP and an increased level of prealbumin were induced by the vitamin C supplementation for 3 months in both groups. However, levels of these biomarkers returned to their original state after the supplementation was withdrawn. Same beneficial effects on plasma albumin, hemoglobin and ERI response to vitamin C supplementation were observed in the two groups without statistical significance. CONCLUSIONS The inflammatory status in MHD patients with plasma vitamin C deficiency and high levels of inflammatory markers could be partially improved by long-term oral administration of small doses of vitamin C. TRIAL REGISTRATION The clinical trial number: NCT01356433.