This book addresses the causes and effects of nutrient deficiencies along the cell-to-communities continuum. The book is primarily concerned with a lack or deficiency of one or more micro- or macronutrients in connection with malnutrition, under nutrition, and starvation. Embedded within the deficiency states is acute restriction whereby food is withdrawn completely for short periods, as when individuals are adhering to religious requirements or undergoing surgical procedures. Further downstream is the consumption of a fraction of the normal diet, as when individuals are dieting or when there is restriction in the amount or variety of food available. The causes of such reductions in dietary intake are varied and also include the social context of poverty, financial limitations, and famine. Refugees and displaced persons may also be vulnerable to under nutrition or total starvation. Diseases may also impact on the total food consumed, such as when there are physical impediments (intestinal obstruction or dysphagia) or anorexia (induced by organic disease or as a disease process per se, ie, anorexia nervosa). This book, organized as approximately 125 chapters in 17 major sections, covers the variable manifestations of dietary restrictions on cells, whole organs, the individual, and societies.