Vitamin D3 or cholecalciferol is a fat-soluble vitamin, usually grouped broadly with other D-complex vitamins as "vitamin D." Vitamin D3 is the only D-complex vitamin that the body produces naturally, which it accomplishes by sun exposure to the skin. If your production of vitamin D3 is insufficient, you must get it from foods, which also satisfies the need for vitamin D2, or ergocalciferol. Foods that contain both vitamins D2 and D3 include fish, eggs, red meats, poultry and organ meats. Many cereals and dairy products are fortified with vitamin D.
Recommended Dosage
The daily recommended dosage of vitamin D3 for everyone under the age of 50 is 5 mcg, equivalent to 200 international units. For those aged 50 to 70, the recommended daily dose is 10 mcg, or 600 international units. Those aged 70 and older should ingest at least 15 mcg per day. Because the body produces both types of vitamin D as a result of sun exposure, individual requirements may be more or less, depending on the amount of time spent in the sunlight.
Excessive doses of vitamin D3 can be toxic. Daily dosages should not exceed 30 mcg, or 2,000 international units. However, this limit modulates based on preexisting conditions; for example, pediatricians may prescribe a single dose of up to 600,000 international units to treat rickets, as the body will store and continue using vitamin D3 over time to treat the illness.
Hypercalcemia
The most serious complication associated with inordinate ingestion of vitamin D3 is hypercalcemia, or excess calcium in the blood. This occurs because vitamin D3 helps manage serum calcium levels. Symptoms include nausea, pain, constipation, poor appetite, vomiting, constipation, muscle weakness and twitching, dementia, apathy, irritability, memory loss, depression, fractures, bone pain, loss of height, spinal curvature and bowed shoulders. A complication associated with hypercalcemia is severe bone loss, resulting in osteopenia.
Renal Complications
Vitamin D3 toxicity can result in renal complications, usually derivative of the impending onset of hypercalcemia. Complications include renal failure, kidney stones, dehydration, hypertension, frequent urination, inordinate thirst and lumbar pain. As a result, treatment for vitamin D3 toxicity often includes dialysis, the use of diuretics, intravenous phosphate, steroids and drugs that prevent calcium resorption. Extremely severe renal complications associated with hypercalcemia or vitamin D3 toxicity can result in coma.
Greater Risk
Although anyone can suffer from vitamin D3 toxicity, those with preexisting habits or conditions are at greater risk. People who receive a lot of sun exposure may not need as much dietary D3 as those who remain indoors most of the time. Those who do not consume much calcium may not incur many of the complications associated with vitamin D3 toxicity, although they may be at greater risk for other health difficulties. Those with conditions such as hyperparathyroidism, sarcoidosis, kidney disease, tuberculosis and histoplasmosis are particularly sensitive to vitamin D3 toxicity, due to the imbalances inherent to these conditions.
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