Along with its most commonly known role in bone growth and development, vitamin D is believed to aid in the prevention and treatment of some cancers, diabetes, hypertension and multiple sclerosis. Some people choose to supplement with vitamin D in order to reap its perceived benefits. These supplements are typically safe at low doses, however high doses should be taken under a doctor's supervision. Although bone tumors are not a reported symptom of vitamin D toxicity, other serious health conditions such as hypercalcemia are.
Vitamin D Sources
Vitamin D is a fat-soluble vitamin and hormone that the body produces when in contact with the ultraviolet B rays of the sun. In addition, other sources of vitamin D include fatty fish, cheese, eggs, fortified milk and supplements. Vitamin D toxicity does not typically occur from foods or sun exposure, however, overdoing it with supplements is possible.
Vitamin D Dosage
The recommended dietary allowance for vitamin D is 600 International Units per day for children and adults up to age 70. In addition, the RDA indicates the tolerable upper limit for adults is 4,000 IU/day. Some believe these recommendations are conservative. For example, The Linus Pauling Institute states that research has shown toxicity to be rare in healthy adults at levels up to 10,000 IU/day.
Vitamin D Toxicity and Bone Tumors
The American Academy of Orthopaedic Surgeons, National Cancer Institute and the Office of Dietary Supplements do not indicate that too much vitamin D causes bone tumors. Still, care should be taken as toxicity can occur from high dose supplementation. Excessive vitamin D intake can lead to hypercalcemia -- high levels of calcium in the blood -- which could lead to heart, kidney and blood vessel damage. The Office of Dietary Supplements indicates that toxicity may occur at supplementation levels between 10,000 to 40,000 IU/day.
Precautions
Although vitamin D has health benefits, It is not advisable to take high dose supplements without your doctor's supervision. If you feel that you are in need of vitamin D, have your doctor measure your 25(OH)D levels. The 25(OH)D is the form vitamin D takes after it has been processed by your liver and is circulating in the blood. From this information, your doctor will be able to determine if you are in need of vitamin D supplements and will be able to suggest a safe dose for your condition.
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