University of Illinois Urbana-Champaign

Effects of hydration physiology on aspects of the gut-brain axis

Willis, Nathaniel

Content Files
WILLIS-DISSERTATION-2023.pdf

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https://hdl.handle.net/2142/121412

Description

Title
Effects of hydration physiology on aspects of the gut-brain axis
Author(s)
Willis, Nathaniel
Issue Date
2023-06-12
Director of Research (if dissertation) or Advisor (if thesis)
Khan, Naiman A
Doctoral Committee Chair(s)
Hoslcher, Hannah D
Committee Member(s)
  • Burd, Nicholas A
  • Muñoz, Colleen
  • Wolf, Patricia G
Department of Study
Nutritional Sciences
Discipline
Nutritional Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
  • hydration
  • copeptin
  • gut microbiota
  • executive functions
  • cognition
  • short chained fatty acids
  • working memory
  • inhibitory control
  • cognitive flexibility
  • intestinal mucus
  • gut barrier
Abstract
Hydration status is an easy-to-measure marker of kidney and general health. This is important as most people in the United States are sub-optimally hydrated despite enjoying free access to safe drinking water. Water intake has been linked to aspects of metabolic syndrome (i.e., obesity, glucose regulation, hypertension), and cognitive performance; suggesting a role in maintaining metabolic and neural homeostasis. Indeed, one of the primary physiologic aims in water regulation is to maintain circulatory function via homeostatic blood volume, pressure, and concentration4; fluctuations in which affect all organ systems in the body. Despite the known importance of water intake, it remains an understudied nutrient. This work has aimed to delineate the effects of variable water intake on cognitive and gastrointestinal function in humans through three primary aims: 1) how fecal microbial metabolites relate to specific domains of executive functioning; 2) relationships between fecal microbial abundance, markers of gut barrier integrity, and biomarkers of hydration status; and 3) how increasing plain water intake alters fecal microbiota community composition and impacts executive functioning in adults. These studies have revealed correlations between fecal butyrate concentration and inhibitory control in subjects with obesity, suggesting that fluctuations in gut saccharolytic fermentative activity may impact cognitive control in the context of metabolic disease. Further, these studies exposed relations between hydration biomarkers, fecal microbiota relative abundance, and circulating LPS in adults; indicating that modulations in water consumption may impact digestive homeostasis and microbiota community composition5. Finally, a single-arm water intake intervention was conducted to further investigate these relationships longitudinally. The findings supported the established literature in demonstrating improvements in attention and memory abilities and subtle shifts in gastrointestinal microbiota relative abundance over the water intake intervention. While this work is hardly a comprehensive view of hydration physiology or the impact it has on the gut-brain axis, it shows the potential for water, as a relatively cheap and easily accessible nutrient, to modulate important aspects of the gut-brain axis. This is an area of research that warrants continued investigation.
Graduation Semester
2023-08
Type of Resource
Thesis
Handle URL
https://hdl.handle.net/2142/121412
Copyright and License Information
Copyright 2023 Nathaniel B Willis

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