Vitamin Toxicity Health Article

Treatment

In all cases, treatment of vitamin toxicity requires discontinuing vitamin supplements. Vitamin D toxicity needs additional action to reduce the calcium levels in the blood-stream because it can cause abnormally high levels of plasma calcium (hypercalcemia). Severe hypercalcemia is a medical emergency and may be treated by infusing a solution of 0.9% sodium chloride into the patient's bloodstream. The infusion consists of two to three liters of salt water given over a period of one to two days.

Prognosis

The prognosis for reversing vitamin toxicity is excellent for most patients. Side effects usually go away as soon as overdoses are stopped. The exceptions are severe vitamin D toxicity, severe vitamin A toxicity, and severe vitamin B₆ toxicity. Too much vitamin D leads to deposits of calcium salts in the soft tissue of the body, which cannot be reversed. Birth defects due to vitamin A toxicity cannot be reversed. Damage to the nervous system caused by megadoses of vitamin B₆ can be reversed, but complete reversal may require a recovery period of over a year.

Prevention

Vitamin toxicity can be prevented by minimizing the use of vitamin supplements. If vitamin D supplements are being used on a doctor's orders, vitamin toxicity can be prevented by monitoring the levels of plasma calcium. The development of hypercalcemia with vitamin D treatment indicates that the patient is at risk for vitamin D toxicity.

BOOKS

Brody, Tom. Nutritional Biochemistry. San Diego: Academic Press, 1998.

Combs, Gerald. The Vitamins. San Diego: Academic Press, Inc., 1992.

Food and Nutrition Board. Recommended Dietary Allowances. 10th ed. Washington, DC: National Academy Press, 1989.

PERIODICALS

Markestad, T., et al. "Intermittent Digh-dose Vitamin D Prophylaxis During Infancy: Effect on Vitamin D Metabolites, Calcium, and Phosphorus." American Journal of Clinical Nutrition 46 (1987): 652-658.

Tzimas, G., et al. "Embryotoxic Doses of Vitamin A to Rabbits Result in Low Plasma but High Embryonic Concentrations of All-trans-retinoic Acid: Risk of Vitamin A Exposure in Humans." Journal of Nutrition 126 (1996): 2159-2171.

Tom Brody, PhD

KEY TERMS

Absorption—The transfer of a vitamin from the digestive tract to the bloodstream.

Ascorbic acid—Another name for vitamin C.

Hypercalcemia—Hypercalcemia is a condition marked by abnormally high levels of calcium in the blood. It is an issue during vitamin D toxicity.

Hypervitaminosis—Another name for vitamin toxicity.

Megadose—A very large dose of a vitamin, taken by some people as a form of self-medication.

Menadione—A synthetic form of vitamin K. It is sometimes called vitamin K₃.

Recommended Dietary Allowance (RDA)—The recommended dietary allowances (RDAs) are the quantities of nutrients in the diet that are needed for good health. RDAs are established by the Food and Nutrition Board of the National Academy of Sciences and may be revised every few years.

Retinol—Another name for vitamin A.