The Effect of Vitamin D on Measures of Bone Health and Gene Expression

Vitamin D, commonly known as the sunshine vitamin, is produced in the skin from sun exposure as well as from dietary sources. However, very few foods naturally contain vitamin D and the amount of vitamin D in fortified foods typically, 100 IU per serving, has been totally inadequate in satisfying adults vitamin D requirement, which is now been estimated to be at least 2,000 IU of vitamin D a day. As a result, vitamin D deficiency is rapidly being recognized world-wide as the most common vitamin deficiency. Upwards of 50-100% of children and adults have been reported as being vitamin D deficient depending on ethnicity, latitude and skin pigmentation. The investigators reported in women at the time of delivery that 76% of mothers and 81% of newborns were vitamin D deficient despite the fact that the mother was taking a prenatal vitamin containing 400 IU vitamin D and drinking two glasses of milk a day. The investigators also reported 30-80% vitamin D deficiency rates in white and black children, healthy young, middle aged and older adults. There have been numerous epidemiologic and clinical observations relating vitamin D deficiency to many chronic diseases and there are many isolated but no comprehensive studies evaluating various genes that are either suppressed or enhanced by 1,25-dihydroxyvitamin D [1,25(OH)2D]. It has been estimated that upwards of 2000 genes are directly or indirectly influence by 1,25(OH)2 D. To date, however, there have not been any genomic signatures identified in humans in response to correction of vitamin D deficiency. The goal of this pilot study is to determine whether or not vitamin D3 supplementation will affect biomarkers for calcium and bone metabolism, and how they alter gene expression biomarkers, especially genes related to the non-skeletal actions of vitamin D.