Are Vitamin D Supplements Safe?

As some vitamins and minerals lead to toxicity or adverse reactions when the recommended dosage is exceeded, some people believe that vitamin D supplements are also unsafe. In order to determine whether the dosage that you take is safe, you need to learn about the recommended dietary allowance as well as about the medical conditions that can be prevented with vitamin D. Vitamin D is a generic name for two fat-soluble vitamins, namely ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3).

Vitamin D Effects and Reference Daily Intake

Vitamin D is known to play a very big role in the absorption of dietary calcium and, thus, in the health of bones. Vitamin D is also able to prevent osteoarthritis progression, multiple sclerosis, high blood pressure and several types of cancer.

Osteomalacia, a bone health problem characterized by defective bone mineralization, can be prevented by using the recommended dietary allowance of 5 mcg. However, the prevention of conditions such as secondary hyperparathyroidism and osteoporosis requires greater dosages.

Vitamin D is also considered a hormone, as it is secreted by the body in the presence of sunlight. Exposing the entire body to sunlight will lead to the production of 250 mcg/day of vitamin D. If such exposure is not possible, you are recommended to take vitamin D supplements, with the condition to respect the recommended dosage.

Toxicity and Side Effects of Vitamin D Supplements

Calciferol supplements become unsafe when people take overdoses of vitamin D. Some people are hypersensitive to this vitamin, which can lead to adverse reactions. Some of the most frequent side effects of vitamin D supplements include:

  • Bone pain
  • Constipation or diarrhea
  • Frequent urination
  • Increased sensation of thirst
  • Loss of appetite
  • Metal taste
  • Muscle pain
  • Nausea
  • Vomiting
  • Weight loss

In addition to the above side effects, which usually appear when doses greater than 25 mcg (1000 UI) are administered, vitamin D supplements can also increase the blood pressure and help in the development of arteriosclerosis.

Calciferol toxicity is one of the main causes of hypercalcemia, a medical condition characterized by atypically high serum calcium levels. Some of the signs that may occur as a result of vitamin D toxicity include bone loss, kidney stones, and calcification of kidneys, heart and possibly other organs. Doses ranging between 1,250 and 5,000 mcg/day lead to anorexia and vomiting in many cases.

Hypersensitivity to Calciferol

People who suffer from primary hyperparathyroidism are most likely hypersensitive to vitamin D. If this is the case, calciferol will make hypercalcemia become even worse. Hypercalcemia is also observed in people who take vitamin D supplements while suffering from lymphoma, sarcoidosis and tuberculosis. In these cases, it is recommended to lower the dose or avoid vitamin D sources completely, both in dietary and environmental forms.

Measures to Take

Talk to your health care provider about taking vitamin D supplements. She can help you understand your recommended dosage, therefore reducing your changes of taking too much. In addition, the doctor will let you know if you are hypersensitive to calciferol. By doing so, you will avoid all the adverse reactions presented above. Overall, vitamin D supplements are safe, provided that you are not hypersensitive and that you respect the dosage recommended by your doctor.


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