#  Dissertation Defense: "High-Quality Diets and Endurance Russing as Ecological Drivers that Shape Human Gut Microbial Structure and Function" 

 



    ![Emily Venable defense poster](/sites/g/files/omnuum1771/files/styles/hwp_5_4__480x385/public/2026-04/Screenshot%202026-04-30%20101330.png?h=205958d6&itok=Q_6edPEs) 

 



 

####  calendar\_today Date and Time 

 **May 7, 2026** 

 11:00AM - 12:00PM EDT 

####  pin\_drop Location 

 **DeVore Room**  



 

 [ Zoom arrow\_circle\_right ](https://harvard.zoom.us/j/91368981997?pwd=Z0gOTgRdE7NaDKQ6YEJxaAS5lLcbBX.1) 

 



 

HEB grad student Emily Venable will defend her dissertation entitled "High-Quality Diets and Endurance Russing as Ecological Drivers that Shape Human Gut Microbial Structure and Function".

**Summary:**

My dissertation studies gut microbiome responses to two human behavioral features: pursuit of a high-quality diet and endurance running. My first chapter argues that human gut microbial communities are unique in part due to our high-quality diets that reduce nutrient flow into the colon, where the vast majority of gut microbes reside. I present a framework, entitled Decoupled Nutrient Status (DNS), rooted in the perspective that as humans shifted toward foods that were more readily digestible in the small intestine, we simultaneously depleted nutrients available to our gut microbes, resulting in host nutrient status being decoupled from, and often negatively correlated with, gut microbial nutrient status. My second chapter tests the hypothesis that ecological changes in the gut lumen during endurance running select for a gut microbiome that contributes more to host energy status, thus buffering the energetic consequences of high physical activity. In both mice and humans, I found that endurance running restructured and stabilized the gut microbiota, increasing gut microbial density and reducing the abundance of mucin-degrading microbes. When transferred to germ-free mice, gut microbiota from runners promoted greater gains in adiposity than did microbiota from non-runners, thus supporting the energy buffering hypothesis. Chapters three and four collectively grapple with a key outstanding problem in studying diet-microbiome interactions: we typically measure diet as it appears on the plate, but survey the microbiome as it appears the colon, where only a fraction of ingested diet remains. I therefore developed and validated methods to quantify the nutrient landscape of the colonic environment using residual dietary DNA in fecal samples. In chapter three, I built a customized DNA reference database from plant foods consumed by the community of Kanyawara chimpanzees (Pan troglodytes schweinfurthii) in Kibale National Park, Uganda. Consistent with the idea that the gut microbiome interacts primarily with the indigestible fraction of diet, I found that diet-derived DNA present in feces was biased toward less digestible components, such as piths and leaves, while underrepresenting fruits. Similarly, in chapter four, which reconstructs diet from fecal samples collected from humans consuming matched plant-based diets in raw versus cooked forms, I found that fecal diet-derived DNA was biased toward low-digestibility substrates, including chia seeds, whereas high-sugar and high-fat substrates were underrepresented relative to consumption. Together, chapters three and four confirm that digestibility shapes the composition of diet in the colon and provides a methodological approach to distinguish between nutrients available to hosts versus microbes. Collectively, my dissertation highlights the unique ecological conditions experiences by our resident microbes as Homo sapiens emerged with implications for microbial contributions to human energy budgets in the past and present.



 

 



 

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