Patients will be randomized in a 1:1 ratio to Vitamin C 500mg orally once daily or matching placebo for 3 months. Randomization codes will be kept by the Research Pharmacy and investigators and patients will be blinded to treatment. Patients currently taking vitamin C supplements (excluding the 100mg of vitamin C contained in a B and C complex vitamin, a supplement used by all peritoneal dialysis patients), will be taken off the vitamin C and then randomized to one of the treatment arms after a 1 month washout period. At the end of 3 months, the effects of vitamin C on the change in transferrin saturation from baseline will be evaluated to identify which patients, if any, benefited from treatment. Hemoglobin, serum iron, total iron binding capacity, ferritin, transferrin saturation and erythropoietin dose will also be assessed. The dose and formulation of recombinant erythropoietin and oral iron will be adjusted during the study period according to standard practice algorithms currently used in the clinic. The addition of vitamin C does not pose any risk to the patients and will be dispensed to the patient by the Research Pharmacy at St. Michael's Hospital free of charge.