From Fork to Feelings: How Foods Shape Mental Health via the Microbiota–Gut–Brain Axis

The microbiota-gut-brain axis, defined as the bidirectional communication linking the gut microbiota with the brain, operates through neural, metabolic, immune, and endocrine signals. It plays an important role in mental health, regulating stress response, mood, and cognitive function, and is altered in psychiatric conditions. Although the gut microbiota remains stable during healthy adulthood, it is modifiable by lifestyle, medication, and diet, making it a tractable target for mental health interventions. Diet is emerging as a viable option to improve mental health through gut microbiota modulation. Energy-dense, high-fat, and high-sugar diets have been linked to poor mental health, whereas Mediterranean, fiber-rich, and fermented-food diets show benefits, possibly through provision of specific nutrients and beneficial microbial metabolites such as short-chain fatty acids. However, more human research addressing variability and confounding is needed to unlock these mechanisms and support personalized/precision nutrition. This review discusses current evidence and proposes multidisciplinary, rigorous diet-microbiota-mental health research.