Associations between Diet, Stress, and Gastrointestinal Health in Endurance Runners

Exercise has been associated with a more diverse and health-promoting gut microbiome. However, endurance exercise, specifically running, causes gastrointestinal distress in some individuals, which is thought to be related to decreased gut blood flow during exercise. A variety of factors modulate the presence of gastrointestinal distress during exercise, including exercise variables and dietary intake. Additionally, diet, exercise, and stress may alter the gut microbiome in ways that impact gut health and the gut’s response to exercise. Therefore, this observational study aimed to assess the associations between dietary factors, gut microbiota composition, psychological stress, and GI symptoms in recreational endurance runners. Data collection included fecal and urine samples, 3-day food and exercise logs, and completion of an online survey. Microbial DNA from fecal samples was extracted and subsequently analyzed via 16S rRNA gene sequencing of the microbiome. Urine samples were analyzed to determine the cortisol level as a biochemical measure of stress. Food and exercise logs were input into NutriTiming software for analysis of overall dietary data. In addition, the survey assessed running habits, gastrointestinal health, and psychological stress. Twelve participants completed the study. Results revealed a trend of higher GI symptom scores during running in individuals who reported consuming food in 1-4 hours prior to a run n=6), compared to individuals who did not (n=6; p=0.011). There were no significant associations between overall dietary intake and GI symptoms. Further research is needed to understand the causes of gastrointestinal symptoms during running, thus allowing for the development of improved nutritional recommendations