Honors Theses

Date of Award


Document Type

Undergraduate Thesis



First Advisor

Colin Jackson

Relational Format



As different diets continue to grow in popularity within the United States, the effect of these diets upon bacteria in the intestines is only beginning to be understood. This study focused on the effect that a shift to a gluten-free diet has on the human gut microbiome. Three genetically close subjects were selected for observation over a six month time period. One subject observed a consistent gluten-free diet. A second subject started on an unrestrictive diet, switched to a gluten-free diet for three months, then returned to an unrestricted diet for an additional three months. The third subject left an unrestricted diet. Fecal samples were taken at set time intervals from each subject and bacterial DNA extracted. Bacterial communities were characterized by 16S rRNA gene sequencing. The subject on a consistently gluten-free diet showed a wide variation in bacterial community structure across their samples for the length of the study, while the subject on an unrestricted diet had little variation in their gut microbiome from the start to end of the study. The subject that alternated between diets showed a change in intestinal bacteria when switching to the gluten-free diet, followed by a return to something resembling the initial gut microbiome when they went back to an unrestrictive diet. However, the overriding factor was that each subject showed evidence of a characteristic gut bacterial community. This study shows that a substantial change in personal diet yields a detectable change in intestinal bacterial populations and diversity, which can then be reversed by a removal of the diet. However the individual nature of the gut microbiome means that a change in diet may not necessarily result in a gut bacterial community that resembles other individuals on that same diet.

Accessibility Status

Searchable text

Included in

Biology Commons



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