Vitamin D Source Levels

Vitamin D plays an important role in overall health. However, many people have low vitamin D levels. These individuals may take vitamin D supplements to boost their vitamin levels. While vitamin D supplements are generally safe, high amounts of vitamin D can cause health problems.

Normally, your body is able to regulate vitamin D levels on its own. However, if you take excessive vitamin D supplements, you may develop toxic amounts of the vitamin in your body. Too much vitamin D results in hypercalcemia, or too much calcium in your blood. Vitamin D toxicity is also known as hypervitaminosis D.

Can I Get Too Much Vitamin D?

You much ingest very large quantities of vitamin D to develop vitamin D toxicity – for example, 50,000 IU (international units) a day over several months. Currently, the Institute of Medicine recommends that adults get no more than 2,000 IU per day to avoid the risk of vitamin D toxicity.

Interestingly, while spending too much time in the sun can cause certain health problems (such as skin cancer or sunstroke), vitamin D toxicity is not one of them. In addition, most food does not contain enough vitamin D for toxicity to be an issue, unless you are frequently ingesting large amounts of cod liver oil. Usually, if your vitamin D intake increases, your body is able to store that excess vitamin D for later use. Only extremely large quantities of vitamin D can result in vitamin D toxicity.

Who Is at Risk for Vitamin D Toxicity?

Taking vitamin D supplements can increase your risk of developing vitamin D toxicity. In addition, certain people may be at greater risk of vitamin D toxicity, including people who:

  • Have kidney problems
  • Have liver conditions
  • Take certain types of diuretics.

People with hyperparathyroidism, sarcoidosis, tuberculosis or histoplasmosis may also be at increased risk for vitamin D toxicity.

Symptoms of Vitamin D Toxicity

Signs of vitamin D toxicity include:

  • Abnormal heart rhythm
  • Constipation
  • Excessive urination
  • Excessive thirst
  • Kidney stones
  • Nausea
  • Nervousness
  • Poor appetite
  • Renal failure
  • Vomiting
  • Weakness.

A blood test can determine if you have too much vitamin D in your body. Usually, blood levels greater than 200 nanograms per milliliter (ng/mL) are considered toxic.

The first step in treating vitamin D toxicity is stopping all vitamin D supplements. Calcium intake may also be restricted, and hydration and medications may also be necessary. People with serious vitamin D toxicity may need to be hospitalized. In severe cases, kidney damage from vitamin D toxicity may be irreversible.

Resources

Mayo Clinic. (2009). Vitamin D. Retrieved December 27, 2009 from the Mayo Clinic website: http://www.mayoclinic.com/health/vitamin-d/NS_patient-vitamind.

Merck Manual for Healthcare Professionals. (2007). Vitamin D. Retrieved December 27, 2009 form the Merck website: http://www.merck.com/mmpe/sec01/ch004/ch004k.html.

National Institutes of Health, Office of Dietary Supplements. (2009). Dietary Supplement Fact Sheet: Vitamin D. Retrieved December 15, 2009 from the National Institutes of Health website: http://ods.od.nih.gov/factsheets/vitamind.asp.

Zeratsky, K. (2009). Vitamin D toxicity: What to do if you get too much? Retrieved December 27, 2009 from the Mayo Clinic website: http://www.mayoclinic.com/health/vitamin-d-toxicity/AN02008.