Probiotics – identification and ways of actions

Abstract

Probiotic bacteria are defined as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. While this beneficial effect was originally thought to stem from improvements in the intestinal microbial balance, there is now substantial evidence that probiotics can also provide benefits by modulating immune functions. In animal models, probiotic supplementation is able to provide protection from spontaneous and chemically induced colitis by down-regulating inflammatory cytokines or inducing regulatory mechanisms in a strain-specific manner. In animal models of allergen sensitization and murine models of asthma and allergic rhinitis, orally administered probiotics can strain-dependently decrease allergen-specific IgE production, in part by modulating systemic cytokine production. Understanding the how probiotic bacteria exert their beneficial effect is crucial for the establishment of definitive selection criteria.