ABSTRACT
The concept of probiotics was fi rst established in 1907 by Metchnikoff, who suggested that the ingestion of fermented dairy products exerted benefi cial effects on health (Metchnikoff 1907). In 1989, Fuller defi ned probiotics as “a live microbial feed supplement which benefi cially affects the host by improving its intestinal microbial balance” (Fuller 1989). In 2002, the Food and Agriculture Organization of the United Nations and the World Health Organization (FAO/WHO) defi ned probiotics as “live microorganisms which if administered in adequate amounts confer a health benefi t on the host” (FAO/WHO 2002). Based on the fact that probiotics prevent or reverse several pathological conditions by stimulating the immune system, Galdeano et al. suggested that probiotics should be defi ned as “live microorganisms that, when included in foods, can infl uence the composition and activity of the gut microbiota, modulate the infl ammatory response, improve the nonspecifi c intestinal barrier, and reinforce or modulate the mucosal and systemic immune response” (Galdeano et al. 2007).
