Vitamin deficiencies may be very common in certain population groups like elderly people, pregnant women, or children. Recent developments in laboratory methods have helped to discover deficiencies that were previously overlooked. This book provides up-to-date knowledge on the role of B and D vitamins in metabolic pathways, gene regulation, risk management, and the prevention of human diseases which have become increasingly important to physicians, clinical chemists, specialists in nutrition, and researchers. It may also help students in studying this special and very interesting field of applied science.