The food glycome: a source of protection against pathogen colonization in the gastrointestinal tract

Trillions of microbes inhabit the gastrointestinal tract of humans with significant differences in the composition and distribution of intestinal flora along its length. Normally there is a symbiotic relationship between the intestinal microflora and the host, with mutual advantages for both partners. When this relationship is altered, commensal bacteria can rapidly shift toward pathogenicity resulting in the onset and progression of gastrointestinal infection. Pathogen adhesion and colonization is often a prelude to infection, and intervention at this early stage can help prevent disease. Bacteria have evolved a multitude of adhesion mechanisms commonly targeting surface carbohydrate structures of the host. Here, we review the ability of various dietary carbohydrates to prevent adhesion of pathogens to host cells. Given their significance in disease, and their ability to cause chronic infection, we have focussed on 3 model pathogens, Helicobacter pylori, Campylobacter jejuni and Clostridium difficile, and dietary carbohydrates which can inhibit their adhesion. The discovery of novel anti-adhesive dietary carbohydrates, once developed as nutraceutical ingredients, may serve as a novel method for preventing infectious diseases in the human gastrointestinal tract. Anti-adhesive carbohydrates used in this context are not bactericidal. Therefore, the spread of pathogens with resistance to antibiotics is less likely to occur.