Your kidneys make up an essential part of your excretory system and prove important to your overall health. Healthy kidneys effectively filter your blood, preventing a buildup of toxins in your body while also protecting against nutrient loss. Your kidneys also have an effect on vitamins within your system, regulating the levels of vitamins present in your blood, as well as the vitamins' activity.
Retain Essential Vitamins
One way that your kidney affects the levels of vitamins in your system is by retaining essential nutrients in your bloodstream. Each kidney contains billions of highly specialized cells, called podocytes. Adjacent podocytes interlock and form molecular filters that allow vitamins, proteins and minerals to remain in your urine. Defects in podocyte health can disrupt this barrier, allowing vitamins to leach into your urine, and potentially leading to vitamin depletion and deficiency. As a result, several patients with chronic kidney disease require regular vitamin supplements to prevent nutrient deficiencies.
Clear Excess Vitamins
While healthy kidneys retain moderate amounts of vitamins in your system, the kidneys also allow excess vitamins to exit your body, preventing a vitamin toxicity. Excess levels of water-soluble vitamins -- such as vitamin C and the eight B vitamins -- pass through the podocyte filter and get excreted from your body. However, your kidney cannot clear excess amounts of every vitamin from your system. It cannot excrete the fat-soluble vitamins A, D, E and K. As a result, over-consuming these vitamins can cause a vitamin toxicity.
Activate Vitamins
In some cases, your kidneys can regulate the activity of vitamins in your system. Your liver contains a store of inactive vitamin D, which it releases into your bloodstream to meet the needs of your body. Cells within your kidneys interact with this inactive vitamin D, chemically converting it into a biologically active form, calcitriol. Once activated, vitamin D can go on to maintain healthy bones, muscles and nerves. As a result, individuals with kidney disease often require calcitriol supplementation, since their kidneys cannot effectively activate vitamin D.
Vitamins in Kidney Disease
While your kidneys can have a range of effects on vitamins in your body, those vitamins can also affect the health of your kidneys. Overdoses of vitamins, such as vitamins A and D, can harm your kidneys -- both vitamins can raise your blood calcium levels, increasing the risk of kidney stones. If you take vitamins or other dietary supplements, talk to your doctor about safe dosages to help protect your kidneys and prevent kidney disorders.
