Can Taking Too Many Vitamins Be Hard on the Kidneys?

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Each of your two kidneys contains nephrons -- specialized filtering structures that support your kidney function. Cells within each nephron form a physical barrier that retains nutrients within your blood, while letting toxins and metabolic byproducts enter your urine. Over the course of your lifetime, exposure to abnormally high levels of nutrients within your blood can lead to kidney strain, eventually increasing your risk for kidney disorders. Some vitamins can have an effect on the health of your kidneys. You should always consult with your doctor before using any type of supplement.

Vitamin D

Taking too much vitamin D can have an adverse effect on the health of your kidneys. Vitamin D toxicity causes a condition called hypercalcemia -- elevated blood calcium levels. Your kidneys must process the added calcium in your bloodstream to help eliminate excess calcium, increasing their workload. If you take too much vitamin D for long periods of time, this can eventually lead to kidney strain and cause kidney stones.


Taking too much niacin could also potentially harm your kidneys in some cases. Moderate niacin proves beneficial, as it helps support your metabolism. However, this vitamin can interact with a number of pharmaceuticals -- and this interaction could harm your kidneys. Specifically, taking nicotinic acid -- a type of niacin supplement -- in combination with some cholesterol-lowering medications can sometimes lead to kidney failure, according to the Linus Pauling Institute. If you take medication to control your blood cholesterol, talk to your doctor about the safety of niacin.

Vitamin C

Too much vitamin C can also negatively affect your kidneys. Excess vitamin C consumption encourages the formation of kidney stones, as this vitamin increases your levels of oxalate, a component of calcium oxalate kidney stones. Only take high doses of vitamin C if instructed by a doctor, and maintain proper hydration throughout the day to help prevent kidney stones.

Other Nutritional Factors and Kidney Disease

In addition to specific vitamins that can cause kidney toxicity, other dietary factors can have an effect on your kidneys. Too much protein, for example, can increase your risk of developing oxalate-containing kidney stones and too much magnesium can cause kidney toxicity. If you suffer from kidney disorders, you should consult a medical professional to determine an appropriate diet to avoid worsening your condition.