Vitamin D in Aging and Chronic Illness

Abstract

The role of vitamin D in calcium homeostasis and its impact on bone is well characterized and validated; however, the role vitamin D plays in non-bone physiology is less concrete. The Vitamin D Receptor (VDR) is expressed throughout the body and regulates many cellular processes. This discovery has led to vigorous research of vitamin D and the role it plays in many illnesses, especially those of high prevalence in the United States. Vitamin D deficiency has been implicated in numerous health conditions and thus is an intriguing target for therapeutic intervention. Studies examining the therapeutic effects of vitamin D in chronic disease and disease prevention have yielded conflicting results. Additionally, many publications on vitamin D result from studies in which vitamin D was not the primary focus. Given the increasing interest in the non-bone effects of vitamin D, we will review and summarize the recent literature related to older adults, a group with significantly increased risk of vitamin D deficiency. Older adults have substantial morbidity and mortality due to dementia, cancer and heart disease, all of which have been linked to vitamin D deficiency. We will explore current evidence of the expression of VDR and the effects of exposure to vitamin D that might impact these illnesses among older adults. We will review the most recent research on cognitive function and depression as a result of vitamin D deficiency. Through this work we aim to summarize the current data that sheds light on the possibility of clinical application of vitamin D therapy.