This up-to-date book presents basic concepts and recent advances in amino acid biochemistry and nutrition, providing comprehensive coverage of developments over the past half-century. It includes information on dietary protein digestion, quality, and requirements, while addressing absorption, transport, synthesis, degradation of amino acids, and intracellular protein turnover in animals. The text integrates cell-, tissue-, and species-specific metabolic pathways of amino acids with health and disease in various organisms. The author also presents a critical analysis of amino acid supplementation to humans and other animals.