This Is AuburnElectronic Theses and Dissertations

Mood Disturbance and the Gut Microbiome




Kristen, Smith

Type of Degree

PhD Dissertation


Nutrition, Dietetics and Hospitality Management

Restriction Status


Restriction Type


Date Available



Microbiota residing in the gastrointestinal tract play a crucial role in physical and mental health of the human host. The gut microbiome affects immunity and inflammation, absorption and digestion of nutrients, production of neuromodulators, and central nervous system function. Microbial diversity is theorized to benefit human health through a range of genes expressed by over 1500 species of microbes. Exploration into the relationship between the gut microbiome and human health has considerably grown in recent years, including a focus on mood and mood-related disorders. Gut microbiota influence communication and signaling in the central nervous system along the gut-brain axis, impacting the response to stress, mood, and quality of life. Most supporting data in this area comes from preclinical studies and a limited number of unique human populations. Herein, we explored the relationship between the gut microbiome and quality of life and mood disturbance in breast cancer survivors, free-living adults, and young adults enrolled in a randomized controlled trial. The first study found differences in fecal microbiome composition between obese and non-obese breast cancer survivors. Several genera previously identified as beneficial were associated with quality-of-life components. In the second study, greater microbial diversity was associated with lower mood disturbance in free-living adults. Quality of diet was also associated with mood states in this study. The third study investigated changes in microbial diversity, dietary components, and body composition, and the relationships between these variables, following a 10-week resistance training regimen. Several microbial taxa associated with mood states in the intervention groups, and overall, microbial diversity increased following the training regimen.