ABSTRACT
Probiotics are live microorganisms, generally bacteria but also yeast which, when ingested in adequate amount, interact with the gut microfl ora and host, having a positive effect on the health of an individual. These bacteria can help to maintain internal microbial balance and defend against harmful bacteria; three mechanisms of promoting human health have been described: (i) providing end-products of anaerobic fermentation of carbohydrates such as organic acids that can be absorbed by the host, these end-products being able to infl uence human mood, energy level and even cognitive abilities, (ii) successfully competing with pathogens, and (iii) stimulating host immune responses by producing specifi c polysaccharides (Saier and Mansour 2005). Probiotics should not cause disease in humans; they should be completely non-pathogenic and should not be able to evolve into pathogenic variants.
