What is the Healthy Gut Microbiota Composition? A Changing Ecosystem across Age, Environment, Diet, and Diseases
UOC di Nutrizione Clinica, Dipartimento di Scienze Gastroenterologiche, Endocrino-Metaboliche e Nefro-Urologiche, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy
Istituto di Patologia Speciale Medica, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
Scuola di Specializzazione in Scienza dell’Alimentazione, Università di Roma Tor Vergata, 00133 Rome, Italy
UOC di Medicina d’Urgenza e Pronto Soccorso, Dipartimento di Scienze dell’Emergenza, Anestesiologiche e della Rianimazione, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy
Istituto di Medicina Interna e Geriatria, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
UOC di Medicina Interna e Gastroenterologia, Dipartimento di Scienze Gastroenterologiche, Endocrino-Metaboliche e Nefro-Urologiche, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy
Author to whom correspondence should be addressed.
Microorganisms 2019, 7(1), 14; https://doi.org/10.3390/microorganisms7010014
Received: 29 November 2018 / Revised: 15 December 2018 / Accepted: 9 January 2019 / Published: 10 January 2019
(This article belongs to the Special Issue Gastrointestinal Microbiota Impacts Human Health and Disease)
Each individual is provided with a unique gut microbiota profile that plays many specific functions in host nutrient metabolism, maintenance of structural integrity of the gut mucosal barrier, immunomodulation, and protection against pathogens. Gut microbiota are composed of different bacteria species taxonomically classified by genus, family, order, and phyla. Each human’s gut microbiota are shaped in early life as their composition depends on infant transitions (birth gestational date, type of delivery, methods of milk feeding, weaning period) and external factors such as antibiotic use. These personal and healthy core native microbiota remain relatively stable in adulthood but differ between individuals due to enterotypes, body mass index (BMI) level, exercise frequency, lifestyle, and cultural and dietary habits. Accordingly, there is not a unique optimal gut microbiota composition since it is different for each individual. However, a healthy host–microorganism balance must be respected in order to optimally perform metabolic and immune functions and prevent disease development. This review will provide an overview of the studies that focus on gut microbiota balances in the same individual and between individuals and highlight the close mutualistic relationship between gut microbiota variations and diseases. Indeed, dysbiosis of gut microbiota is associated not only with intestinal disorders but also with numerous extra-intestinal diseases such as metabolic and neurological disorders. Understanding the cause or consequence of these gut microbiota balances in health and disease and how to maintain or restore a healthy gut microbiota composition should be useful in developing promising therapeutic interventions.
Keywords: gut microbiota; diversity; health; diet; nutrition; age; milk feeding; necrotizing enterocolitis; weaning; enterotypes; irritable bowel syndrome; inflammatory bowel disease; celiac disease; colorectal cancer; obesity; type 2 diabetes; Alzheimer’s disease; Parkinson’s disease; hepatic encephalopathy; autism spectrum disorders; personalized medicine