[Regulation of the intestinal flora by food]

Abstract

The purpose of probiotics is to regulate the bacterial colonisation of the digestive tract. In contrast to antibiotics, with the probiotics it is not a certain metabolic product of bacteria or fungi with a known spectrum of antimicrobial activity which, for example when used as performance enhancers under the conditions permitted according to the EEC guidelines for feed additives, reduce the numbers of bacteria, which appear in the small intestines of domestic animals and compete with the host for nutrients and vitamins, but there it is rather the living micro-organisms themselves which are intended to, to help to improve the performance of domestic animals on the basis of a fundamentally different mechanism of action. Recent findings on the effect of the phenomena of bacterial competition on the processes of an infection, with penetration, adhesion, and multiplication as prerequisites for development of the parasitic mechanism of a pathogen, have shown that by controlling the processes of colonization of the intestines with micro-organisms and also their metabolic activity it is possible to at least reduce the incidence of the diarrhoeal diseases which are responsible for the the greatest economic damage. The numerical displacement of bacterial pathogens is not the only effect of the bacterial competition resulting from the orally administered micro-organisms. The fact that antagonistically acting bacteria or yeasts prevent the pathogenic species from entering the intestinal epithelial cells plays a role here. As a result of which, especially the small intestines are not colonized by pathogens (E. coli and others), the liver is largely relieved of substances accumulating in the course of bacterial protein metabolism, the absorption of fatty acids and other energy-providing compounds is increased, and not readily soluble salts are transformed into soluble compounds. Effects comparable to those obtained with small amounts of antibiotics added to the feed of farm animals as regards increased growth rate and improved feed conversion, can also achieved with the addition of probiotics.