The human gut microbiome is a diverse population of microorganisms. The development of native microbiome starts at birth and is highly adaptable to changes with age, food habits, lifestyle, and physiological conditions (ailments). Advanced “omics based” techniques are aiding in identifying and establishing the quantitative and qualitative metabolic profiles, activity profiles, and complex interactions between gut microbiota and many physiological ailments, including obesity, intestinal bowel diseases, type 2 diabetes, and several types of cancers. Several studies have identified a direct relation between gut microbiota composition and subject’s health including in aging and neurologi¬cal ailments. Therefore, internal microbiota composition might become one of the critical factors in maintaining good health as well as a crucial indicator of disease theranostics. This book explores all the dimensions for microbiota composition, in relation with geriatric health issues, and provides insight into the available contemporary medicine and traditional or alternative strategies for the treatment and prevention of diseases.