Is Vitamin C Intake too Low in Dialysis Patients?

Abstract

Vitamin C has several well-established roles in physiology including synthesis of collagen, carnitine and epinephrine, absorption of dietary iron, and mobilization of storage iron for erythropoeisis. Loss of several of these functions explains the pathology of scurvy, where defective collagen synthesis and anemia are major symptoms. Vitamin C deficiency is very common in dialysis patients and may arise from dialytic vitamin C clearance, restricted intake of vitamin C-rich foods, and increased vitamin C catabolism in vivo from inflammation. In the dialysis population, greater vitamin C intake may be needed for optimal health. Relationships between intake, body distribution, inflammation, and dialytic losses are complex and need further study. Concern about vitamin C metabolism leading to accumulation of tissue oxalate has led to the recommendation that vitamin C intake equals, but not exceeds, the intake recommended for the general population. Vitamin C deficiency in dialysis patients may have clinical consequences; a study in Renal Research Institute clinics found an association with periodontal disease. Data also support a role for vitamin C in prevention of dialysis-related anemia. New research questions are proposed in this editorial, with a discussion of strategies to determine the optimal provision of vitamin C for CKD patients.

Plasma vitamin C levels in ESRD patients and occurrence of hypochromic erythrocytes

“…Vitamin C can be measured prior to start of therapy, and patients with chronically low levels of vitamin C are of special interest in this regard, which highlights the utility of adding routine vitamin C assessment to the ESRD clinical panel. Potential oxalic acid toxicity must be considered, although this problem has not been seen with any frequency since the establishment of 3×/week high‐flux HD treatment . Hepcidin levels, although characteristically elevated in ESRD, have not been shown to be a useful indicator of the response to ESA and iron therapy.…”

“…ESRD patients often have very low plasma levels of vitamin C and vitamin C was previously shown to aid mobilization of stored iron . Low levels of vitamin C observed in ESRD may contribute to the impaired iron delivery that leads to hypochromic RBC.…”

Oxidative stress in hemodialysis: Causative mechanisms, clinical implications, and possible therapeutic interventions

“…Vitamin C deficiency is common among dialysis patients and greater intake may contribute to better health . On the other hand, the aforementioned studies were diverse in terms of population, follow‐up length, doses used, and parameters measured.…”

Vitamins (A, C and E) and oxidative status of hemodialysis patients treated with HFR and HFR-Supra

“…Vit. C deficiency is very common in dialysis patients mainly because of low dietary intake, losses during dialysis and accelerated catabolism [4–6]. Low levels of Vit C may have clinical consequences and associations with increased cardiovascular morbidity and mortality have been found [7, 8].…”