- Recommended dosage:400 IU for children aged 0-1 year (1) 600 IU/day for children aged 1-18 years (1)1500-2000 IU/Day for all men and women older than 18 years (1) To decrease the inconvenience of daily vit. D and pt's non-adherence to vit. D taking, may prescribe weekly vit. D dosage instead (1)

Vitamin D production in the skin declines with advancing age, making elderly populations more dependent on dietary vitamin D. For the average older person, higher dietary intake of vitamin D may be required to achieve optimal serum levels of 25(OH)D. (1)