Normal, Healthy, and Optimum Level of 25-Hydroxyvitamin D and Required Daily Intake of Vitamin D

There is controversy about the normal blood levels and daily requirement for vitamin D, an essential nutrient that functions like a hormone. The controversy stems from differences in views about the role of vitamin D in optimum health versus lack of disease, scope of tissues affected and processes affected by vitamin D, variations among ethnic groups, differences in exposure to sunlight, and lack of harmonization of analytical methods. The normal value for 25-hydroxyvitamin D, stated by different organizations, ranges from 10-60 ng/mL and the recommended daily intake varies from 400 IU to 4000 IU/day. We address the controversy about normal blood levels and suggest that the approach for establishing normal levels should focus on optimal health rather than lack of disease. We are inclined to recommend 30ng/mL as the lower limit of normal and desirable levels of 25-hydroxyvitamin D to be established as 50ng/mL.Levels consistently higher than 200ng/mLare associated with toxicity, however, given the current state of knowledge the upper limit of normal should be capped at 80ng/mL.Depending on the health status, sun exposure, intake of medications, we recommend that total daily intake of vitamin D should be about 1000 IU/day to prevent bone disease and about 2000 IU/day to promote optimal health. Special populations (e.g. nursing home residents, those with severe deficiency) may require higher doses. Daily supplements of 4000 IU are generally considered safe.