Tolerable upper limits of vitamin D, which "should not be exceeded without medical supervision," include the following: 1000 IU/day for infants aged up to 6 months, 1500 IU/day for infants aged 6 months to 1 year old, 2500 IU/day for children aged 1 to 3 years, 3000 IU/day for children aged 4 to 8 years, and 4000 IU/day for everyone older than 8 years. However, the guideline states that for individuals who are vitamin D deficient, higher levels of vitamin D (2000 IU/day for children up to age 1 year; 4000 IU/day for children aged 1 - 18 years, and up to 10,000 IU/day for adults aged 19 years and older) "may be necessary to correct, treat, and prevent vitamin D deficiency," Dr. Holick said. "Both vitamin D2 and vitamin D3 is equally fine in treating and preventing vitamin D deficiency," he added. #vitamin-d #health #pub