New tests and studies continue to reveal exciting information about the power of vitamin D in maintaining good health and preventing major illnesses. ‘Why Does Vitamin D Matter?’ not only covers vitamin D basics, but also explores the science of the vitamin D receptor (VDR), the protein that binds to the active metabolite of vitamin D to fulfill biochemical functions, it explains how vitamin D analogs directly activate the VDR. Readers will find this e-book informative, not only from the scientific point of view, but also from the potential applications of the knowledge into one’s daily life. Starting with a brief history of vitamin D and VDR research, followed by a detailed scientific report of how vitamin D and VDR work, this e-book goes on to cover epidemiological studies that investigate the outcome of vitamin D deficiency and the effects of vitamin D supplementation. Issues related to vitamin D supplementation are also addressed from different angles. This e-book continues with a comprehensive report on the numerous vitamin D analogs currently on the market or in development to treat various diseases, followed by exploring the possibility of developing this class of compounds for additional indications. This e-book is suitable for both general readers and scientists involved in vitamin D research or students who are interested in a career in biochemical/medical/nutritional research, especially in the field of vitamin D and the vitamin D receptor.