since the 1930s when milk was first fortified with vitamin d to prevent rickets the usual recommendation has been 200 iu to 400 iu daily during times of inadequate sun exposure. women above age 50 should be receiving 400 iu to 800 iu. recently experts in the area have been lobbying for a new recommended level of 1 000 iu daily among adults. the food and nutritional board at the institute of medicine began reviewing the published studies in 2008. . . for comparison the upper tolerable limit (adverse results begin to appear) has been reputed to be 2 000 iu/day. many researchers in the field have suggested that the toxic level is closer to 10 000 iu/day over a more prolonged period of time.
how much vitamin d is recommended?