Date of Award

Summer 2023

Project Type

Thesis

College or School

COLSA

Departments (Collect)

Agriculture, Nutrition, and Food Systems

Program or Major

Nutritional Sciences

Degree Name

Master of Science

First Advisor

Maria Carlota Dao

Second Advisor

Sherman Bigornia

Third Advisor

Kelley Thomas

Abstract

The gut microbiome has a significant influence on chronic diseases, potentially through mediating inflammation and the gut-brain axis, yet underlying pathways remain unclear. Microbiomes are highly variable and can be influenced by a variety of lifestyle and environmental factors, like diet and medication use. The study of both the composition and function of the gut microbiome is warranted, yet many gaps remain particularly in our knowledge about the gut microbiome function in the context of chronic diseases. Refugee groups in the US, such as the Bhutanese refugee population in New Hampshire, are at higher risk for chronic diseases but underrepresented in current research. Therefore, this project sought to characterize the gut microbiome composition and functional potential among Bhutanese refugee adults in NH in regard to glycemic status, inflammation, satiety regulation, fiber intake, and medication use. Data on health information and dietary intake was previously collected from (n=50) Bhutanese refugee adults, with a high prevalence of overweight, obesity and type 2 diabetes (T2D). Inflammation and satiety biomarkers were measured in plasma samples using electrochemiluminescence immunoassays. Microbiome data was examined via shotgun sequences of fecal samples and analyzed using validated bioinformatic pipelines and R packages. Compositional richness and diversity were lower in those with T2D, while functional diversity was not significantly different. Protein-coding genes related to the biosynthesis of lipopolysaccharide (LPS) were predictive of plasma C-reactive protein, lipopolysaccharide binding protein (LBP, a marker of intestinal permeability), fasting plasma glucose, and insulin. Further, LBP was positively associated with Hemoglobin A1c, fasting plasma glucose, and Homeostatic Model Assessment for Insulin Resistance. While there were no significant associations between gut microbiome composition or function with satiety regulation and fiber intake, findings suggest an association between microbially produced LPS, inflammation, and glycemic regulation that could be a potential target of future therapeutics or interventions.

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