Vitamins: benefits & CKD-specific cautions
- Andrew Kowalski
- Sep 10
- 2 min read
Vitamin D (D3/D2; calcifediol/calcitriol separately)
Potential benefit: corrects deficiency, improves PTH abnormalities in CKD-MBD; may help bone/mineral parameters. Evidence for hard renal outcomes is mixed.
Key CKD cautions: monitor Ca/P/PTH; avoid indiscriminate “high-dose” use in stages 3–5; active forms reserved for specific indications of secondary hyperparathyroidism.
Practical: check 25-OH-D and treat deficiency; recheck and titrate.
Vitamin A (retinol)
Potential benefit: treat true deficiency (rare in high-income settings).
Key CKD cautions: retinol is renally cleared—accumulates in CKD; avoid routine supplementation due to toxicity risk (bone, liver, intracranial HTN). Prefer beta-carotene from foods if needed.
Vitamin C (ascorbic acid)
Potential benefit: treat deficiency; small doses (e.g., 60–100 mg/day) can help anemia management and iron absorption.
Key CKD cautions: high doses can raise oxalate → oxalate nephropathy and stones; avoid megadoses (>500–1,000 mg/day) in advanced CKD/dialysis.
Vitamin E
Potential benefit: antioxidant; limited CKD-specific outcome data.
Key CKD cautions: can increase bleeding risk with anticoagulants/antiplatelets; avoid high-dose chronic supplementation. (General risk; manage case-by-case.)
Vitamin K (K1/K2)
Potential benefit: theoretical vascular calcification benefits are under study; deficiency possible with restricted diets.
Key CKD cautions: interacts with warfarin; supplementation must be coordinated with anticoagulation clinic.
B-complex (thiamine, riboflavin, niacin, B6, folate, B12)
Potential benefit: water-soluble Bs are commonly used to replace dialytic losses (renal multivitamins); B12/folate correct megaloblastic anemia; B6 sometimes used for neuropathy.
Key CKD cautions: Niacin can worsen insulin resistance and uric acid; very high-dose B6 → neuropathy; folate/B12 won’t improve outcomes unless deficient. Use “renal-dose” multis rather than high-dose single agents.
Magnesium (supplement or Mg-containing antacids/laxatives)
Potential benefit: emerging data suggest Mg repletion may favorably affect vascular calcification parameters in CKD if monitored.
Key CKD cautions: hypermagnesemia with excessive supplements or Mg-containing laxatives/antacids—risk rises with eGFR <30; monitor levels if supplementing.
Potassium (pills, “lite salt,” “K-salt” substitutes)
Potential benefit: BP lowering in the general population.
Key CKD cautions: Avoid OTC K⁺ supplements and K-enriched salt substitutes in CKD due to hyperkalemiarisk—especially with RAASi/MRA/SGLT2 use; always clear with clinician/dietitian.
Omega-3 fatty acids (fish oil, EPA/DHA)
Potential benefit: may reduce triglycerides and CV risk; renal outcomes/proteinuria effects are inconsistent across trials.
Key CKD cautions: bleeding risk with high doses plus anticoagulants/antiplatelets; watch for GI upset.