Probiotic Microorganisms for Shaping the Human Gut Microbiota - Mechanisms and Efficacy into the Future

Summary The use of bacteria as beneficial biological agents to be used as food ingredients or as active components of food supplements dates back to the early 1900’s. These bacteria must reach the human gut in a viable form and in numbers sufficiently high to attain a substantial presence amongst the thousands of bacteria inhabiting the gut; they have also to exert some beneficial action. These beneficial actions have been supported by hundreds of papers, the vast majority of them dealing with subjects in which the ratio among the different bacterial groups of the gut were altered by pathological conditions; the administration of probiotic bacteria are able to restore the function of the gut microbiota. In healthy people the action of probiotics is possibly related to different mechanisms, linked to strain-specific action of probiotics and relying on the replacement of some autochthonous bacteria with specifically selected probiotic strains.