Why Does Vitamin d Matter?: Vitamin D and your Body - Paperbackby J. Ruth Wu Wong (Author) 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