Vitamin D deficiency is a worldwide problem linked to numerous diseases affecting men, women, and children of all ages. Enormous progress in the study of vitamin D has been made since the first edition of this highly-acclaimed book was published nearly 20 years ago, and current research continues to draw headlines. Feldman and Pike’s Vitamin D, Fifth Edition continues to build on the successful formula from previous editions, taking the reader from the basic elements of fundamental research to the most sophisticated concepts in therapeutics. The two comprehensive volumes provide investigators, clinicians, and students with a comprehensive, definitive, and up-to-date compendium of the diverse scientific and clinical aspects of vitamin D, where each area is covered by both basic and clinical experts in the field. In Volume I: Biochemistry, Physiology and Diagnostics, international experts in endocrinology, bone biology, and human physiology take readers through the basic research of vitamin D. This impressive reference presents a comprehensive review of the multi-faceted actions of vitamin D relating both to skeletal and extra-skeletal action. Researchers from all areas of vitamin D will gain insight into how clinical observations and practices can feed back into the research cycle and will, therefore, be able to develop more targeted genomic, proteomic and metabolomic insights into the mechanisms of disease. Volume II: Health, Disease and Therapy authoritatively covers the evidence for new roles of vitamin D, ranging from organ transplantation to cancer, diabetes, inflammatory bowel disease, multiple sclerosis, and renal disease. The coverage is appropriately broad, drawing on aspects of internal medicine, pediatrics, nutrition, orthopedics, oncology, neurology, obstetrics and gynecology, and immunology, as well as, new areas for vitamin D including liver metabolism, veterinary medicine and ICU care – including COVID-19. Clinical researchers will gain a strong understanding of the molecular basis for a particular disease and better understand future directions for research in this still-growing field.