Is there pandemic vitamin D deficiency in the black population? A review of evidence

Although 1,25-dihydroxyvitamin D [1,25(OH)2D] is the biologically active form of vitamin D, measurement of the total serum 25-hydroxyvitamin D [25(OH)D] level is the gold standard used to define vitamin D status. Currently, it is widely accepted that serum 25 (OH) D levels below 20 ng/ml defines vitamin D deficiency. According to this definition, there appears to be pandemic vitamin D deficiency in the Black population. However, there is no evidence of higher-thannormal rates of common complications and symptomology of true vitamin D deficiency in the Black population. What is going on? We researched the MEDLINE databases to find studies, from 1967 to present, that directly compare between Blacks and Caucasians the following: serum vitamin D level, serum calcium level, serum parathyroid hormone level, bone mineral density and health, and non-skeletal risks associated with vitamin D deficiency. The available studies consistently show that Blacks tend to have serum 25(OH)D levels in the deficient range while their serum 1,25(OH)2D level is similar to, if not even slightly higher than that of Caucasians, and that the serum Ca level in Blacks is virtually identical to that in Caucasians. Therefore, it appears that the serum 25(OH)D level is not the best marker of vitamin D sufficiency or deficiency in Blacks. In the future, clinical evaluation of the vitamin D status in the Black population needs to consider other serum biomarkers such as 1,25(OH)2D and/or bioavailable 25(OH)D.