A new study indicates that at least 2,000 International Units (IU) of vitamin D3 -- which is currently considered the upper limit of intake -- are needed to ensure adequate blood levels of the vitamin for post-menopausal African-American women.
Over 200 women took part in this three-year, double-blind, placebo-controlled study, which adds to a growing body of evidence suggesting that there is an urgent need to review current recommended daily intake levels of the vitamin.
Vitamin D3 is produced in the skin during exposure to sunlight. However, increased skin pigmentation reduces the effect of UVB radiation, meaning darker-skinned people are more at risk of vitamin D deficiency.
As much as 4000 IU per day may be required for individuals who are already deficient in the vitamin.