Chapters authored
The Intricate Relationship between Diabetes, Diet and the Gut Microbiota
The most recent World Health Organization report revealed that the number of adults suffering from diabetes has almost quadrupled since 1980 to 422 million, thus drawing attention to the urgent need to step up prevention and treatment of this disease. This chronic ailment is often associated with serious complications such as increased risk of heart disease, stroke and kidney failure. In 2012 alone, diabetes lead to 1.5 million deaths. This dramatic rise is mainly due to the increased prevalence of type 2 diabetes and factors driving it include overweight and obesity. Novel studies in this area have advanced our understanding regarding the complex relationship between diet, gut microbiota and diabetes. Despite no clear microbiota signature is associated with diabetes, patients harbour a reduction of butyrate-producing species (Faecalibacterium prausnitzii, Roseburia intestinalis) as well as an increase in opportunistic pathogens. Furthermore, the functions of the gut microbiome (i.e., vitamin metabolism, transport of sugars, carbohydrate metabolism, short chain fatty acid (SCFA) synthesis, etc.) are also different in patients with type 2 diabetes, a fact that may significantly alter the course of disease. Diet is one of the most decisive factors that have an impact on the gut microbiome. Nutritional interventions using prebiotics (i.e., inulin-type fructans), polyphenols and arabinoxylans have been employed for the treatment of diabetes. Besides the shifts produced by these dietary components in the microbiome composition, it is worth mentioning their impact on host physiology through modulation of gut peptide production and glucose metabolism. The information presented within this chapter summarizes the most recent advances in the study of the microbiome-diet-diabetes interplay and analyses how these novel findings can be used in order to establish new therapeutic approaches for those with diabetes.
Part of the book: Pathophysiology
Dysbiosis, Tolerance, and Development of Autoimmune Diseases
The pathogenesis of autoimmune diseases (AIDS) is not only attributed to genetic susceptibility, but also to environmental factors, among which, those disturbing gut microbiota have attracted increasing attention lately. Healthy gut microbiota has beneficial effects on the development and activity of the immune system, playing a central role in peripheric tolerance. Compositional and functional changes in gut microbiota were reported in various AIDS, and increasing evidence suggests that disturbed gut microbiota contributes to their immunopathogenesis. Thyroid and intestinal diseases prevalently coexist—for instance, Hashimoto’s thyroiditis and Graves’ disease are the most common autoimmune thyroid diseases and often co-occur with celiac disease. This association can be at least explained by increased intestinal permeability, allowing antigens to cross the barrier more easily and activate the immune system. The passage of microbial antigens into the internal environment may break the self-tolerance, generating the production of autoantibodies and/or autoreactive T cells. In this chapter, we briefly present the roles of intestinal microbiota in human physiology, with a focus on the role of microbiota in immune tolerance.
Part of the book: Immunology of the GI Tract