Objective: Pre-clinical evidence suggests that the gastrointestinal microbiota contributes to mood and behavior disorders. Among humans, diet quality and patterns, which also impact the gastrointestinal microbiota, have been linked to depression, anxiety, and stress. This review summarizes findings from clinical studies using dietary intervention to improve depression, anxiety, or stress and the role the gastrointestinal microbiota may have in these disorders.
Methods: A literature search was conducted using the keywords microbiome, microbiota, depression, anxiety, stress, diet, dietary pattern, diet quality, fiber, prebiotics, probiotics, and mood.
Results: Mood was improved by enhancing diet quality. Fructooligosaccharide and galactooligosaccharide improved anxiety and depression in participants consuming ≥ 5 g/day. Additionally, bifidobacteria were enriched in subjects consuming ≥ 5 g/day. Probiotic consumption improved psychological or biological measures of depression, anxiety, or stress in individuals predisposed to a mood disorder. Probiotics suppressed biological markers of stress in healthy individuals in a strain-dependent manner.
Discussion: High-quality diets, prebiotics, and probiotics may beneficially affect mood. Habitual diets rich in dietary fiber and omega-3-polyunsaturated fatty acids may be linked to reduced risk of developing symptoms of depression, anxiety, and stress; however, additional studies are necessary. Certain probiotics may enhance mood, but their influence on the gastrointestinal microbiota requires further investigation.
There is increasing evidence that the gastrointestinal microbiota influences human health, and metabolic, gastrointestinal, and psychological diseases. Preclinical and clinical evidence suggest that the gastrointestinal microbiota influence mood and behavior, including depression, anxiety, and stress. Similarly, diet, eating behaviors, and consumption of fiber and prebiotic fibers affect the composition and metabolic functions of the human gastrointestinal microbiota. Clinical research has revealed diet quality, as well as specific dietary components and dietary supplements aid in prevention or treatment of symptoms of depression, anxiety, and stress. Specifically, high diet quality, prebiotic fiber consumption, and probiotic supplements reduced anxiety symptoms and had anti-depressant effects in humans. The exact role the gastrointestinal microbiota play in the development of mental disorders is still being elucidated, but its involvement in bidirectional communication between the brain and gastrointestinal tract via the gut-brain axis is presumably a fundamental link between the microbiota and mood disorders. Delineating the relationship between diet, the gastrointestinal microbiota, and mental health is important for future applications of diet therapy for the treatment of depression, anxiety, and stress. Herein, we review and discuss dietary and microbial factors that may influence the symptoms of depression, anxiety, and stress. The primary focus of this article is on the outcomes from dietary intervention trials conducted in human subjects.
Gut microbiota and mood
The brain-gut-microbiota axis is a bidirectional communication network that allows gastrointestinal microbes to convey information to the brain, and for the brain to communicate with the gastrointestinal tract. The mechanisms by which microbes affect mood in humans are not fully known, but pre-clinical studies have demonstrated that the gut microbiota plays an important role in mental health. For example, depression symptoms have been transferred via fecal microbiota transplant from depressed humans to rodents…