Probiotics, Live Biotherapeutic Products (LBPs), and Gut-Brain Axis Related Psychological Conditions: Implications for Research and Dietetics

It is well-known that probiotics have key roles in the crosstalk between the gut and brain in terms of nutrition and health. However, when investigating their role in nutrition and health, it can be important to discriminate probiotics used as foods, food supplements, or drugs. For clarification of this terminology, the Food and Drug Administration (FDA) has established a new "live biotherapeutic products" (LBP) category, expressing pharmaceutical expectations and to reduce confusion in the literature. Growing evidence advises that the community of microorganisms found in the gut microbiota is associated with psychological conditions. Hence, it is thought that LBPs may positively affect depression, anxiety, bipolar disorder, and schizophrenia by reducing inflammation, improving gut microbiota, and balancing gut neurometabolites. This review focuses on the specific position of probiotics as LBPs in psychological conditions. Condition-specific potential pathways and mechanisms of LBPs and the prominent strains are discussed in the light of novel studies for future research, dietetic and pharmaceutical applications.