Vitamin D deficiency, atherosclerosis and cancer

Abstract: Recently there has been intense interest to find if vitamin D deficiency may be related to cardiovascular disease, cancer and infection. Inadequate saturation with vitamin D may adversely affect immune and metabolic functions, causing non-skeletal medical disorders. Sunlight exposure induces vitamin D synthesis in the skin from a precursor, 7-dehydrocholesterol. Since the body produces vitamin D, this "vitamin" does not fulfill classical definition for a vitamin, being rather a prohormone. Vitamin D provided in the food has smaller role than the source synthesized in the skin. Vitamin D is hydroxylated in the liver into 25-OH-D. Because this product has a longer biological half life, it is the best indicator of body stores of vitamin D. Biologically active form is the next metabolite, 1-25 (OH)2 D. This product has a high binding affinity to a protein nuclear vitamin D receptor (VDR). Receptors for vitamin D have broad tissue distribution, including vascular smooth muscle, endothelium and even malignant cells. Deficiency of vitamin D in populations is high (30-60% in the USA and Europe). This is particularly true about the northern latitudes where there are insufficient UV-B rays to promote the skin synthesis. In addition, there are campaigns to control sun exposure (fear of skin cancer), together with reduction in outdoor activities. No wonder that in aging people, in chronically ill and in subjects requiring long-term hospitalization, deficiency of vitamin D is very frequent and may adversely affect already compromised immunologic functions and resistance to infection (Fig. 6, Ref. 43).