Recommended Vitamin C Dose in CKD
For adults with CKD at risk of vitamin C deficiency, supplement with at least 90 mg/day for men and 75 mg/day for women to meet recommended intake levels 1.
Dosing Algorithm by CKD Stage
CKD Stages 1-5 (Non-Dialysis)
- Target dose: 90 mg/day (men) or 75 mg/day (women)
- This represents the standard RDA and should be achieved through diet or supplementation if dietary intake is inadequate 1
- Recent evidence shows vitamin C inadequacy/deficiency affects 80% of CKD stage 4-5 patients, with median plasma levels of only 22 μmol/L (normal >35 μmol/L) 2
CKD Stage 5D (Dialysis Patients)
- Target dose: Consider 1000 mg twice daily (2000 mg/day total) to maintain normal plasma concentrations 3
- Rationale: Vitamin C is cleared during dialysis with a sieving coefficient of ~1.0, meaning it passes freely through dialysis membranes
- Conventional hemodialysis removes 58 mg per session; nocturnal hemodialysis removes 128 mg per session 2
- Despite higher supplementation rates (median 113 mg/day), 58% of dialysis patients still have inadequate/deficient plasma levels 2
- The 2 g/day dose has a solid pathophysiological rationale and good safety profile in critically ill patients on RRT 3
Post-Transplant
- Target dose: 90 mg/day (men) or 75 mg/day (women)
- 48% of kidney transplant recipients have inadequate/deficient vitamin C status despite adequate kidney function 2
Key Clinical Considerations
Assessment approach:
- Periodically assess dietary vitamin C intake through 24-hour dietary recalls 1
- Consider multivitamin supplementation for those with sustained inadequate dietary intake 1
- Monitor for clinical signs of deficiency (fatigue, poor wound healing, bleeding gums)
Important caveats:
- Do NOT exceed recommended doses without clear deficiency, as excessive vitamin C (>1000 mg/day chronically) theoretically increases oxalate production, though short-term high doses have not shown increased stone risk 3
- Vitamin C enhances iron absorption and mobilization, which may benefit anemic dialysis patients on erythropoietin 4
- The inverse relationship between dietary vitamin C intake and CKD prevalence suggests adequate intake may have protective effects 5
Practical implementation:
- For CKD 1-5 (non-dialysis): Start with dietary optimization; supplement if intake <75-90 mg/day
- For dialysis patients: Strongly consider supplementation with 1-2 g/day given persistent losses and high deficiency rates
- For post-transplant: Assess intake and supplement to RDA levels if inadequate
The KDOQI 2020 guidelines provide conservative recommendations based on expert opinion, while emerging pharmacokinetic data in dialysis patients suggests higher doses may be necessary to overcome dialysis-related losses and achieve normal plasma concentrations 3, 2.