This is a comprehensive book that focuses on the prevalence of vitamin deficiencies, particularly vitamin B12 and vitamin D, in the South Indian population. The book delves into the association between vitamin B12 and folic acid with homocysteine levels among individuals with varying degrees of glucose tolerance. The book sheds light on the nutritional status of the South Indian population, including the prevalence of malnutrition, dietary intake, absorption, metabolism, and bioavailability of micronutrients. It explores the impact of vitamin deficiencies on the elderly population, including anemia, osteoporosis, cognitive impairment, and neuropathy. Moreover, the book discusses the association between vitamin deficiencies and chronic diseases such as cardiovascular disease, diabetes mellitus, metabolic syndrome, insulin resistance, hypertension, hyperlipidemia, chronic kidney disease, cancer, inflammation, and autoimmune disorders. It also delves into genetic polymorphism and its impact on vitamin metabolism. The book highlights the importance of screening, diagnosis, and treatment of vitamin deficiencies, including supplementation, fortification, and lifestyle modifications. It emphasizes the need for public health initiatives aimed at promoting awareness of the importance of adequate vitamin intake and the role of health education in improving nutritional status. The book is based on cross-sectional, prospective, and observational studies and intervention studies, providing valuable insights into the epidemiology of vitamin deficiencies in the South Indian population. Overall, this book is an essential resource for healthcare professionals, researchers, and policymakers interested in improving the nutritional status and health outcomes of the South Indian population.