Vitamin D is an essential nutrient the body uses for a variety of functions, including the regulation of hormone production, healthy growth of bones and proper calcium absorption. Each day, the human body needs between 400 and 800 international units, or IU, of vitamin D to maintain these functions, depending on your age. However, if you consume too much vitamin D, you may be at risk of developing vitamin D toxicity.
Cause
Vitamin D toxicity is primarily caused by the excessive use of vitamin D supplements. Anyone aged 9 or older may be at risk of developing unusually high blood levels of this mineral if they take more than 4,000 IU of vitamin D daily. The tolerable upper intake levels for vitamin D for infants and children up to age 8 range between 1,000 and 3,000 IU. Vitamin D toxicity may occur if infants, children or adults consistently take more than the tolerable upper intake levels for their age group over the course of several months. There is no established vitamin D dosage that causes acute vitamin D toxicity. However, a 2007 article published in "The American Journal of Clinical Nutrition" reports that acute vitamin D toxicity may occur following treatment with a daily dose of 600,000 IU vitamin D for several days. Though your body produces vitamin D naturally when your skin is exposed to sunlight, too much sunlight does not cause vitamin D toxicity.
Signs and Symptoms
Vitamin D helps your body absorb calcium. When your blood levels of vitamin D are abnormally high, your calcium levels also increase significantly. Toxicity symptoms related to vitamin D overdose are typically the result of hypercalcemia, or high blood calcium levels. Such signs and symptoms initially include reduced appetite, unintended weight loss, increased urination, weakness, fatigue and heart rate irregularities. You may also feel nauseated or develop recurrent bouts of constipation. Consult your medical provider as soon as possible if you exhibit vitamin D toxicity symptoms.
Health Complications
Persistently high vitamin D and calcium levels may cause life-threatening health complications. You may develop kidney stones, bone loss or calcification of your vital organs. Unfortunately, kidney damage and organ calcification may cause permanent medical problems.
Treatment Options
The goal of vitamin D toxicity treatment is to lower your blood levels of this mineral. Your doctor will initially recommend ending treatment with any supplements that contain vitamin D. Treatment with corticosteroids and bisphosphonates can help reduce your calcium levels. In addition, your doctor may administer saline solution by IV to help flush excess vitamin D and calcium from your body. Your doctor may also recommend maintaining a low-calcium diet until your blood levels of vitamin D and calcium return to normal.
References
- Linus Pauling Institute at Oregon State University; Dr. Victoria J. Drake; January 2008
- The Merck Manuals Online Medical Library; Vitamin D; Dr. Larry E. Johnson; April 2007
- MayoClinic.com; Vitamin D Toxicity: What if you get too much?; Dec. 11, 2010
- Office of Dietary Supplements; Vitamin D; Feb. 25, 2011
- "The American Journal of Clinical Nutrition;" Risk Assessment for Vitamin D; JN Hathcock, et. al; January 2007
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