Vitamin D and cardio-metabolic health in the elderly

Abstract

Abstract Chapter 1 of this thesis introduces the reader to the background of the main topic – vitamin D, its metabolism and physiological effects. Since its discovery vitamin D has been recognized as an important factor in calcium homeostasis and bone metabolism. Recently, there has been extensive research performed on possible extra-skeletal effects of vitamin D. Nowadays vitamin D deficiency has been linked to a higher risk of many prevalent diseases such as cardio-vascular disease or type 2 diabetes mellitus. Based on this new research it is considered that improving vitamin D status may be a cost-effective tool to improve public health. The main objective of this thesis was to investigate the association of vitamin D and cardio-metabolic health. Chapter 2 presents a systematic review and meta-analysis of observational studies and randomised controlled trials (RCTs) on vitamin D and the risk of mortality. The objective was to evaluate the extent to which circulating biomarker and supplements of vitamin D are associated with mortality under various circumstances. With this meta-analysis we found that the evidence from observational studies shows inverse associations of circulating 25-hydroxyvitamin D with risks of vascular, cancer and nonvascular-noncancer deaths. Further we found that supplementation with vitamin D3 reduces overall mortality among older adults significantly; however, further investigations are required to establish the optimal dose and duration, and whether vitamin D3 affects mortality risk differently than vitamin D2. In chapter 3 we investigated the associations between vitamin D and metabolic outcomes. More specifically, in chapter 3.1 we focused on possible association between vitamin D status and prevalence of metabolic syndrome in the elderly since the findings on this topic in the elderly are inconsistent. The aim was to evaluate the association between vitamin D status and the metabolic syndrome in the elderly, as well as between vitamin D status and the components of metabolic syndrome (i.e. serum glucose, triglycerides (TG)