Honors Program

University Honors, Honors in Health Sciences: Human Health

Date of Award


Thesis Professor(s)

W. Andrew Clark

Thesis Professor Department

Allied Health Sciences

Thesis Reader(s)

Michelle Chandley


The gut microbiota and its metabolites – namely short chain fatty acids (SCFAs) – interact with the digestive, immune, and nervous systems. Microbiota with disrupted composition are highly associated with obesity, gastrointestinal symptoms, and chronic inflammation. Levels of SCFAs in the feces can represent dynamics of the microbiota, and they represent one mechanism by which the microbiota interacts with its host. This study aimed to further our understanding of associations between microbiota bacterial diversity and SCFAs, immune markers, BMI, and GI symptoms and to identify bacteria that are differentially abundant in different BMI groups and with synbiotic supplementation. Data (SCFAs, immunoglobulins, body mass index, fecal fiber, fecal protein, measures of GI symptoms, and 16s RNA sequences, n=11) was extracted from a randomized control trial investigating the effects of synbiotic supplementation in non-celiac gluten-sensitive participants. QIIME2 was used to process 16s RNA data, analyze quantitative, qualitative, phylogenetic quantitative, and phylogenetic qualitative measures of alpha and beta diversity and to perform an analysis of composition of microbiomes (ANCOM) for identification of differential abundances. Multiple metrics of alpha diversity were found to significantly correlate with IgG4, IgM, IL-2, acetate, propionate, isobutyrate, valerate, isovalerate, caproate, heartburn, urgent need to defecate, and feelings of incomplete evacuation. Multiple metrics of beta diversity were significantly different between normal and overweight, normal and obese, and overweight and obese BMI classification groups. Beta diversity was also found to significantly correlate with IgG1, IgG3, IgG4, IgA, IL-6, IL-8, fecal fiber, propionate, butyrate, heartburn, acid regurgitation, nausea and vomiting, bloating, abdominal distension, increased gas, and eructation. The synbiotic intervention did not significantly alter alpha or beta diversity. An ANCOM identified bacterial taxa differentially abundant with BMI shifts and synbiotic supplementation, though these taxa were not those included in the synbiotic. Findings demonstrate alpha and beta diversity associations with various SCFAs, GI symptoms, immune markers, and BMI, and the results of the placebo-controlled intervention suggest careful consideration of placebo contents moving forward. This research supports plans to apply analysis to larger sample sizes to elucidate changes microbial profiles that are associated with clinically relevant biomarkers and symptoms.


East Tennessee State University

Document Type

Honors Thesis - Open Access

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.


Copyright by the authors.