Prebiotics

Abstract

The human large intestine is an intensively colonized area containing bacteria that are health promoting as well as pathogenic. This has led to functional food developments that fortify the former at the expense of the latter. Probiotics have a long history of use in humans as live microbial feed additions. In contrast, a prebiotic is a nondigestible food ingredient that beneficially affects the host by targeting indigenous components thought to be positive. Dietary carbohydrates, such as fibers, are candidate prebiotics, but most promise has been realized with oligosaccharides. As prebiotics exploit nonviable food ingredients, their applicability in diets is wide ranging. Main prebiotic targets at the moment are bifidobacteria and lactobacilli (although this may change as our knowledge of the microbiota diversity and functionality expands). Any dietary component that reaches the colon intact is a potential prebiotic; however, much of the interest in the development of prebiotics is aimed at nondigestible oligosaccharides such as inulin-type fructooligosaccharides (FOS) and trans-galactooligosaccharides (TOS). In Europe, FOS and TOS have been shown to be prebiotics, through numerous volunteer trials, as evidence by their ability to positively change the gut flora composition after a short feeding period. Other prebiotics are emerging. Some prebiotics occur naturally in several foods such as leek, asparagus, chicory, Jerusalem artichoke, garlic, artichoke, onion, wheat, banana, and oats. However, these foods contain only trace levels, so developments have taken the approach of removing the active ingredients from such sources and adding them to more frequently consumed products in order to attain levels whereby a prebiotic effect may occur, for example, cereals, confectionery, biscuits, infant feeds, yogurts, table spreads, bread, sauces, drinks, etc. As gastrointestinal disorders are prevalent in terms of human health, both probiotics and prebiotics serve an important role in the prophylactic management of various acute and chronic gut-derived conditions. Examples include protection from gastroenteritis and some inflammatory conditions.