Neurochemicals released by probiotics in the gut may affect the brain and influence mood. Mark Lyte, from Texas Tech University Health Sciences Center (Texas, USA) proposes a new field known as microbial endocrinology, where microbiology meets neuroscience, advancing  new ideas on how neurochemicals delivered directly to the gut via probiotic intestinal microbiota could exert beneficial effects in maintaining gastrointestinal health and psychological well-being.  Acknowledging a variety of health benefits gained from the ingestion of probiotics that have been reported by previous studies, the researcher observes that a definitive mechanism has not yet been identified to account for the ability of orally administered bacteria to modulate a number of biological processes. Proposing that a shared mechanism essentially links the neural and immune responses to probiotic administration that leads to the health effects, the author discusses specific probiotics, such as Lactobacilli and Bifidobacteria, and how the active uptake of neurochemicals, generated by bacteria in the gut and circulated through a patient’s bloodstream, may represent a pathway for probiotics to exert extra-intestinal effects including behavioral changes.  The researcher concludes that: “This unifying microbial endocrinology-based hypothesis, which may facilitate the selection and design of probiotics for clinical use, also highlights the largely unrecognized role of neuroscience in understanding how microbes may influence health.”