Currently, there is no "standard of care" for persons with low vitamin D. At the VA Medical Center, providers use a variety of supplement regimens. The Institute of Medicine (IOM) has published 600 IU per day (4200 IU per week) as the Recommended Daily Allowance (RDA). By definition, the RDA is the amount of a vitamin or supplement that will prevent 97-98% of the population from becoming deficient.