Most people take 400 IU per day, a safe amount for adults. In fact, of all published cases of vitamin D toxicity for which a vitamin D amount is known, only one occurred at a dose under 40,000 IU per day. Nevertheless, people wishing to take more than 1,000 IU per day for long periods of time should consult a physician. People should remember the total daily intake of vitamin D includes vitamin D from fortified milk and other fortified foods, cod liver oil, supplements that contain vitamin D, and sunlight. 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. Certain medications may interact with vitamin D. Refer to the drug interactions summary for a list of those medications. 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.