Pre- and probiotic overview.

The dynamic relationship between gut microbiota and its human host is also known as a trophic association that might range from commensalism, where only the microbe enjoys a positive effect from the relationship, to intestinal symbiosis where both host and microbe benefit from their interaction. In the last years, we have started to understand how alterations of the gut microbiota composition leading to the disruption of host-microbial interactions are associated and/or predispose individuals to disease conditions ranging from inflammatory bowel diseases to allergy and functional gastrointestinal disorders, such as irritable bowel syndrome. While we await important insights in this field, the microbiota is already a therapeutic target. Based on the actual definitions, prebiotics are defined as substrates that are selectively utilized by host microorganisms conferring a health benefit, while probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. Although their health promoting activities encompasses numerous effects, including immunostimulation, competitive exclusion of pathogens, and gut barrier enhancement, the exact mechanism of action by which these compounds exert their beneficial actions in humans is only partially known. In this review, we highlight the current insights into the clinical applications of prebiotics and probiotics in gastroenterology.