ABSTRACT
The concept of probiotic bacteria as therapeutics was proposed more than a century ago by the Russian Nobel laureate Elie Metchnikoff (Metchnikoff and Mitchell 1907). Since then, numerous research groups have studied probiotics and suggested diverse health benefi ts for the human host, i.e., remodeling of the gut microbial community and suppression of pathogens, decreased incidence of diarrhea, competitive exclusion of pathogens, improving cellular immunity, or decreased levels of cholesterol in the blood to name just a few (for a review see O’Flaherty and Klaenhammer 2010). Today, benefi cial microbes applicable by food have become a widely-used and vital component of multi-billion dollar dairy and functional food industry. Despite the strong evidence for the functional claims on probiotics, our knowledge about the specifi c molecular mechanisms, by which these probiotic microbes adapt to the gut environment and elicit specifi c health benefi ts for the human host, is still scarce. Due to the lack of understanding of probiotics action, widespread scepticism about the validity of their health benefi ts appeared (Baugher and Klaenhammer 2011). In order to protect the consumers against misleading information, economical losses and health
* Corresponding author: riedela@uni-greifswald.de
damage, the World Health Organization (WHO) and the European Food Safety Authority (EFSA) have defi ned essential requirements, which need to be fulfi lled before microbial food-additives can be declared as probiotics (EFSA 2007, Food and Agriculture Organization of the United Nations and World Health Organization 2006, van Loveren et al. 2012). In conclusion, potential probiotics and their benefi cial effect(s) on human health need to be thoroughly investigated before they may be introduced to the market (Fig. 1).
