When healthy, the kidneys are responsible for the continuous filtration of blood in order to maintain fluid, electrolyte, and organic solute balance in the body. However, when the kidneys are damaged, they are no longer able to do this. Dialysis, used in end stage renal disease (also referred to as renal failure, chronic kidney disease, and kidney failure), it is a process where a machine filters the blood since the kidneys are no longer able to. In addition to the inability to filter blood, renal failure results in the body’s inability to make some vitamins and minerals (example: vitamin D), as well as difficulty excreting excessive amounts of certain vitamins and minerals (example: phosphorus).
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The kidney’s role in vitamin and mineral metabolism
Normally, we are able to get adequate amounts of vitamins and minerals by eating a wide variety of foods. However, many patients on dialysis must follow dietary restrictions, making it difficult for them to get the necessary amounts of certain vitamins and minerals to stay healthy. In addition to this, many vitamins and minerals are lost during the process of dialysis. Therefore, many dialysis patients are at risk for vitamin and mineral deficiencies. Since vitamins are necessary for proper metabolism, protein building, and growth it is important for the health of dialysis patients that they are supplemented with any vitamins or minerals that they may be deficient in.
General overview of vitamins and minerals
Vitamins can be divided into two groups: water-soluble vitamins and fat-soluble vitamins. Water-soluble vitamins include vitamin C and the B vitamins (folate, thiamine, riboflavin, niacin, pantothenic acid, biotin, vitamin B6, vitamin B12). Most dialysis patients will need to supplement vitamin C and B vitamins to replace what is lost in the dialysis solution. Fat-soluble vitamins include vitamins A, D, E, and K. Excessive amounts of these vitamins can be harmful for people with kidney failure because they can build up in the body and become toxic so they are not generally supplemented in dialysis patients. However, vitamin D is sometimes an exception to this generalization. A doctor will prescribe vitamin D if it is necessary.
Nutrients to avoid in dialysis
There are some nutrients that are restricted in renal failure patients because of the body’s inability to excrete excessive amounts of them due to the kidneys not functioning properly. In general, these nutrients include:
Vitamins and minerals to supplement in dialysis
Many foods that contain phosphorus and potassium (restricted in dialysis patients) also contain folate, niacin, riboflavin, and vitamin B6 (water-soluble vitamins). Therefore, restricting foods that contain phosphorus and potassium can lead to deficiencies in other important vitamins. In general, the following vitamins and minerals are supplemented in dialysis patients:
Nutrition for patients on dialysis varies on an individual basis. It can be very confusing trying to determine which vitamins and minerals need to be supplemented and which do not so it is important for dialysis patients to speak with a doctor before making any changes to their nutritional plan.