Human body has since been shown to be crawling with bacteria, human microbiome includes skin, gut and you guessed it, mouths. Stomach, which hosts the largest colony, prevents invasion from bugs , also manages many bodily functions like vitamin and hormone secretion.Father of modern medicine, Hippocrates, Said that ‘all disease begins in the gut. http://www.drstevenlin.com/how-bacteria-solved-the-french-paradox