Why We Should Speak of the Microbiota–Gut–Brain–Mind Axis: Beyond Reductionisms

Recent discoveries regarding the interactions between the microbiota, intestinal barrier, and nervous system have popularized the concept of the microbiota–gut–brain axis. However, this formulation still risks underestimating the bidirectional causal role played by psychological and sociocultural processes in human health and disease. This paper proposes extending the traditional microbiota–gut–brain axis into a microbiota–gut–brain–mind (M.G.B.M.) axis, to better represent the integrated bio-psycho-social nature of the human holobiont and to avoid reductionistic interpretations that equate psychological phenomena exclusively with neural activity. The M.G.B.M. axis further reinforces the need for a PNEI-oriented interpretation of the microbiota–gut–brain–mind axis, highlighting the reciprocal interactions among psychological states, neural regulation, endocrine responses, immune activity, intestinal permeability, and microbial ecology. The proposed framework may provide a more comprehensive theoretical basis for future microbiota research and for the development of integrative clinical approaches to health and disease.