Dysbiosis

Dysbiosis refers to a disruption in the composition, diversity, and function of the microbial communities that inhabit the human body — most notably the gut microbiota — typically marked by a loss of beneficial microorganisms, an overgrowth of potentially harmful ones, and/or reduced overall microbial diversity. Within nutritional psychology, gut dysbiosis is of particular interest because it can disrupt signaling along the microbiota–gut–brain axis, contributing to neuroinflammation, altered neurotransmitter and short-chain fatty acid production, and increased intestinal permeability — processes implicated in depression, anxiety, and other mental health conditions. Diet is among the most powerful modifiable drivers, with ultra-processed, low-fiber Western patterns promoting dysbiosis and fiber-rich, plant-forward diets supporting microbial balance.