Associations Between Health Behaviors, Gastrointestinal Symptoms, and Gut Microbiota in a Cross-Sectional Sample of Cancer Survivors: Secondary Analysis from the Chemo-Gut Study

Background: Health behaviors, such as diet and exercise, are actions individuals take that can potentially impact gastrointestinal (GI) symptoms and the gut microbiota. Little is known about how health behaviors impact GI symptoms and the gut microbiota after anti-cancer therapies. Methods: This is a secondary analysis of a cross-sectional study that investigated relationships between GI symptoms, gut microbiota, and patient-reported outcomes in adult cancer survivors. Gut microbiota was assessed from stool samples using 16 S rRNA gene sequencing. GI symptoms and health behaviors were measured via self-report. Descriptive statistics, multiple regression, and correlation analyses are reported. Results: A total of 334 cancer survivors participated, and a subsample of 17 provided stool samples. Most survivors rated their diet as moderately healthy (55.7%) and reported engaging in low intensity exercise (53.9%) for <= 5 h/week (69.1%). Antibiotic use was associated with more belly pain, constipation, and diarrhea (P < .05). Survivors consuming a healthier diet had fewer symptoms of belly pain (P = .03), gas/bloating (P = .01), while higher protein consumption was associated with less belly pain (P = .03). Better diet health was positively correlated with Lachnospiraceae abundance, and negatively with Bacteroides abundance (P < .05). Greater exercise frequency positively correlated with abundance of Lachnospiraceae, Faecalibacterium, Bacteroides, Anaerostipes, Alistipes, and Subdoligranulum (P < .05). Conclusion: Results provide evidence for associations between antibiotic use, probiotic use, dietary health behaviors, and GI symptoms. Diet and exercise behaviors are related to certain types of bacteria, but the direction of causality is unknown. Dietary-based interventions may be optimally suited to address survivors' GI symptoms by influencing the gut microbiota. Larger trials are needed.