April 2013, updated December 2014
Erythropoietin (EPO) and iron are commonly used to treat patients suffering from chronic kidney disease (CKD). But should CKD patients use other supplements to maintain and improve their health?
Patients following a CKD diet can experience low levels of vitamins and minerals because they are avoiding high fiber foods, eating more protein, or limiting certain fruits – or in other words, not eating a balanced diet. CKD also changes the body’s ability to make Vitamin D. And dialysis patients lose water soluble vitamins (Vitamins B and C) during dialysis treatments.
The value of nutritional supplementation was affirmed in a recently-published study that found consuming renal-specific oral nutrition supplements at home improved the weight, muscle mass, and bone mass in malnourished CKD patients. Supplementation also reduced EPO dosages and improved measures associated with reduced illness and mortality.
For that reason, physicians recommend that CKD patients take a Vitamin B complex, Vitamin C and Vitamin D supplement. But CKD patients should be aware of the benefits and pitfalls of vitamin and mineral supplements.
Healthy kidneys excrete Vitamin C (ascorbic acid). If kidneys are unable to filter wastes, then oxalate crystals (ascorbic acid by-products) are deposited elsewhere in the body. The oxalate crystals will accumulate in the blood, then in the eyes, bones, muscles, blood vessels, heart and other organs. Oxalosis will become progressively more severe as the blood oxalate concentration remains high, and can lead to death. Among CKD patients, dosages of more than 100 milligrams (mg) daily of Vitamin C can lead to acute and chronic renal failure. The ideal Vitamin C dosage for CKD patients is 75 to 90 mg daily. 
Similarly, when kidneys are unhealthy, they cannot remove excess potassium in the body. If potassium builds in the body, then hyperkalemia (high potassium in the blood) occurs. This can lead to weakness, numbness and tingling, and worse case an irregular heartbeat or even a heart attack. The recommended dietary intake for healthy adults is 4,700 mg daily. A potassium-restricted diet for CKD patients is typically only 2,000 mg daily.
Healthy kidneys convert Vitamin D into the biologically-active form, 25-(OH) Vitamin D, that regulates calcium and bone metabolism. If the kidneys are unhealthy, then insufficient 25-(OH) Vitamin D is synthesized. The result is that even when calcium intakes are adequate, the body will not absorb calcium. Among healthy individuals, experts are now recommending 4,000 International Units (IU) of Vitamin D daily. To overcome a CKD patient’s Vitamin D deficits, dosages of more than 4,000 IU may be required. 
Vitamin and mineral supplementation may help CKD patients maintain better health. But unsupervised self-medication has inadvertently led to acute renal failure and death. For that reason, CKD patients should always consult with a physician before any self-treatment and before taking any supplements.
 See “Link between Kidney Disease, Iron, and Lance Armstrong”, www.anrminerals.com
 Sezer S, Bal Z, Tutal E, Uyar ME, Acar NO, “Long-Term Oral Nutrition Supplementation Improves Outcomes in Malnourished Patients with Chronic Kidney Disease on Hemodialysis, Journal of Parenteral and Enteral Nutrition, January 16, 2014.
 “Nutrition in CKD”, The Renal Association, <www.renal.org/guidelines/modules/nutrition-in-ckd#sthash.uBxDkyXL.dpbs > (accessed Dec 9, 2014)
 “Vitamin C Supplementation and CKD”, Renal & Urology News, <http://www.renalandurologynews.com/vitamin-c-supplementation-and-ckd/article/138500/ > (accessed December 10, 2014)
 “Dietary Reference Intakes (DRIs): Recommended Intakes for Individuals, Elements”, Food and Nutrition Board, Institute of Medicine, National Academies of Science, 2004
 “Potassium and Your CKD Diet”, National Kidney Foundation, <https://www.kidney.org/atoz/content/potassium> (accessed Dec 11, 2014)
 Williams S, Malatesta K, Norris K, “Vitamin D and Chronic Kidney Disease”, Ethnicity and Disease, Autumn 2009.
 Nankivell B, and Murali K, “Renal Failure from Vitamin C after Transplantation”, New England Journal of Medicine, January 24, 2008; McHugh G, Graber M, and Freebairn R, “Fatal vitamin C-associated acute renal failure”, Anaethesia and Intensive Care, pp 585-8, July 2008