One in seven adults has been reported to be vitamin D deficient. Vitamin D deficiency is particularly common in the elderly. Individuals with sarcoidosis who have elevated blood levels of calcium, and people with hyperparathyroidism should not take vitamin D without consulting a physician. Anyone wishing to take more than 1,000 IU per day for long periods of time should consult a physician. In addition, people who receive adequate sunlight exposure do not need as much vitamin D in their diet as do people who receive minimal sunlight exposure.
Vitamin D increases both calcium and phosphorus absorption.
Vitamin D has also been reported to increase absorption of aluminum. For the convenience of the reader, the information in the table listing the supplements for particular conditions is also categorized. Vitamin D and multiple sclerosis. Vitamin D and pancreatic islet function. Time course for changes in insulin secretion and content during vitamin deprivation and repletion.