Many people get too little Vitamin D. However, there are also health risks for people who get excessive, or toxic, quantities of Vitamin D. While anyone can get too much Vitamin D and experience toxic effects, pregnant women have to exercise particular caution with this vitamin.
Symptoms of Too Much Vitamin D
Excessive dosages of Vitamin D can cause nausea, vomiting, constipation, weakness, a decline in appetite and weight loss, anorexia, bone pain and headaches. Since Vitamin D aids in the absorption of calcium, getting too much of it can cause increased blood levels of calcium, a condition known as hypercalcaemai. Over time, this can lead to hypertension and heart and kidney damage. This condition can cause calcium and phosphate deposits in soft tissues, including kidneys. Of normal adults who get an excessive dose of 100,000 IU a day for several weeks or months, researchers conclude 20 percent will develop hypercalcaemia.
Because of the interrelationship, calcium and Vitamin D are often packaged together in supplement form. One study identified a 17 percent increase in kidney stone risk for postmenopausal women taking high levels of these supplements over many years.
Risks for Pregnant Women
Pregnant women who get too large doses of Vitamin D put their infants at risk for hypercalcaemia. There is also evidence that toxic doses of Vitamin D can inhibit parathyroid function in newborns, which can lead to seizures. Excess doses have also been linked to congenital birth defects.
Sunlight, Food and Vitamin D Toxicity
Excessive sun rays don't lead to Vitamin D toxicity. Normal dietary consumption doesn't either. An exception is very large quantities of cod liver oil regularly ingested. Instead, toxicity is most likely to be caused by excessive supplementation.
According to the Institute of Medicine, Food and Nutrition Board, large doses administered in the short-term don't cause toxicity. But long-term supplementation in excess has been linked to toxicity. This is because excess Vitamin D is stored in our bodies over time.
Knowing How Much is Too Much
The amount of Vitamin D needed to reach toxicity varies from person to person. Daily ingestion of more than 2,000 IU in children or 75,000 IU in adults may produce toxic symptoms. Pregnant women taking 1,000 IU to 4,000 IU per day may pass on toxicity to their newborns. Most known cases of toxicity have been the result of more than 50,000 IU a day over a period of several years.
Recommended Dosage
The current U.S. Department of Agriculture recommended daily dose of Vitamin D is 200 IU for adults 50 and younger, and 400IU for people aged 51 to 70. The Vitamin D Council recommends much higher daily doses for healthy adults of 2,000 IU for those who get a fair amount of exposure to the sun.
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