While many people worry about not getting enough vitamins, patients with advanced kidney disease are in the uneasy position of simultaneously lacking some vitamins while having toxic levels of others. Since bodies with impaired kidneys process nutrients differently, working with a renal dietitian or a nephrologist is essential.
Vitamin A
Studies such as the one published by F. Montazerifar and colleagues in the January 2010 "Journal of Renal Nutrition" show that most adult patients on dialysis have abnormally high levels of vitamin A. This finding is also observed in children on dialysis. While extreme toxicity is not common, watch for changes in hair, skin and nails, if you have advanced kidney disease, because these are indications of vitamin A toxicity.
Vitamin C
Vitamin C toxicity is generally not a problem for healthy people because this vitamin is water soluble and any excess is excreted into the urine. However, vitamin C can be a problem for kidney patients who are less capable of producing urine because oxalate deposits can form in bone and soft tissue. Oxalates are a family of chemicals that bind with calcium to form kidney stones and other calcium type deposits. Kidney patients can prevent this problem by limiting their intake of vitamin C to between 60 and 100 mg per day.
Mineral Restriction
Patients with advanced kidney disease also tend to have high serum levels of potassium and phosphorus. High levels of potassium cause nerves to misfire, which can cause the heart to beat irregularly. High levels of phosphorus pull calcium from the bones, causing them to be permanently weakened. Patients who must restrict dietary intake of these minerals often become malnourished because many fruits and vegetables must be eaten sparingly.
Solution
Given that kidney patients can easily be malnourished while simultaneously having too much vitamin A, renal vitamins are specially formulated to supply sufficient amounts of B and C vitamins without including vitamin A. These vitamins also include a biologically active form of vitamin D because kidney patients are not able to use the form of vitamin D found in food or manufactured by the body after exposure to sunlight.
References
- "Journal of Medicinal Food;" Hemodialysis Alters Lipid Profiles, Total Antioxidant Capacity, and Vitamins A, E, and C Concentrations in Humans; F. Montazerifar, et al.; December 2010
- "Journal of Renal Nutrition;" Serum Retinol, Retinol-Binding Protein, and Transthyretin in Children Receiving Dialysis; N. Fassinger, et al.; January 2010
- DaVita: The ABCs of Vitamins for Kidney Patients
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