Vitamin D for Human Body

Vitamin D is a vital regulatory hormone necessary for healthy human physiology. The official duty of vitamin D is calcium homeostasis; yet, and vitamin D deficiency correlates with both calcium related conditions such as osteoporosis and rickets and non calcemic-related ailments such as autoimmune disease, cardiovascular disease, diatebes, and cancers of the breast, colon, and prostate.

Prostate cancer is of particular concern because African American men are overly affected by both vitamin D deficiency and prostate cancer risk. African Americans not only display prostate cancer at an earlier age, but they are 50% more likely to develop prostate cancer and have twice the mortality compared to European Americans. Skin pigmentation is the largest predictor of vitamin D deficiency in the United States because the UV induced synthesis of vitamin D is the dominant source of the active form of vitamin D and is inhibited by melanin. Therefore, more than 65% of African American men are deficient with serum levels below 20ng/ml over 90% are vitamin D insufficient.

Richards et. al. describes the earliest assessment of the prostatic and vitamin D axis in samples from a disparate cross-sectional group of radical prostatectomy subjects. Vitamin D metabolites were measured in both prostate tissue and serum. Gene expression patterns participating in transport, vitamin D metabolism, and the vitamin D receptor were quantified in the prostatic epithelial tissues.

The results show that African Americans were vitamin D deficient in the serum and had increased amounts of the active form of vitamin D in their prostate tissues. It was also found that the levels of vitamin D receptor mRNA were expressed higher in African Americans compared to European Americans. More importantly, gene expression of Megalin, which binds and internalizes vitamin D along with its carrier protein, significantly positively correlated with West African Ancestry. This is of particular interest because Megalin also binds and internalizes sex hormone binding globulin, which is the carrier protein for testosterone, the precursor to dihydrotestosterone; a known driver of prostate cancer.