People get vitamin D when sun exposure causes the skin to make vitamin D as well as from dietary supplements, vitamin D-fortified foods and the very few foods in which vitamin D occurs naturally. Fat-soluble vitamins, such as vitamin D, are stored in the body for longer periods than water-soluble vitamins and do not require daily replacement. While vitamin D overdose is rare for healthy people eating a well-balanced diet, it can occur if you use larger-than-recommended doses of the dietary supplement. Vitamin D overdose, or toxicity, can have serious health consequences.
Vitamin D
The U.S. Department of Agriculture recommended daily intakes for vitamin D are 10 mcg for infants, 15 mcg for people age 1 to 69 and for lactating or pregnant females, and 20 mcg for adults over 70. Your body uses vitamin D to develop and maintain teeth and bones, which is especially important for children. Vitamin D helps your body increase its absorption of calcium from the small intestines, and it is important for your body's use of phosphorous. Vitamin D-fortified dairy products are the major dietary source of vitamin D. Other food sources are fortified fruit juices, beef liver, oily fish and egg yolk. Cod liver oil is also a source of vitamin D.
Upper Intake Levels and Toxicity
The National Institutes of Health, or NIH, cautions against exceeding recommended upper intake levels, or ULs, which range from 25 mcg to 100 mcg depending on age and refer to the highest daily intake levels of vitamin D your body can safely tolerate. Vitamin D toxicity, which is known as hypervitaminosis D, is a medical condition that occurs when you have dangerously high levels of vitamin D in your body. The NIH reports the threshold for vitamin D toxicity as 10,000 to 40,000 IU/day.
Overdose Risks
Vitamin D overdose is more likely to result from taking high levels of vitamin D supplements. Overdose also can occur when you eat excessive amounts of vitamin D-fortified foods while taking high doses of vitamin D supplements. Regular use of vitamin D supplements is especially risky for children since their bodies make enough vitamin D with just five to ten minutes of sun exposure. People who take high levels of vitamin D supplements to reduce their risk for certain medical conditions could have increased risk of overdose. Serious medical conditions or use of certain kinds of diuretics increases your risk for vitamin D overdose.
Health Concerns
Vitamin D overdose can result in hypercalcemia, which is too much calcium in your blood. The symptoms of hypercalcemia include weakness, confusion, constipation, loss of appetite, nausea, vomiting, kidney stones, frequent urination, tissue calcification and abnormal heart rhythms. Hypercalcemia can damage your kidneys, blood vessels and heart. Toxic levels of vitamin D can retard mental and physical growth and development.
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