Consumption of resistant potato starch produces changes in gut microbiota that correlate with improvements in abnormal bowel symptoms: a secondary analysis of a clinical trial.

Background: Studies have linked a lack of dietary fibre, including resistant starch (RS), to disease-associated changes in intestinal bacteria. Healthy people often report abnormal bowel symptoms (ABS), including bloating, constipation, abdominal pain, and diarrhea, however, connections between these symptoms and the gut microbiota are poorly understood. Determining correlations between ABS and taxonomic groups may provide predictive value for using prebiotics to mitigate ABS in combination with stool microbiome testing.

Methods: Post hoc analysis of a three-arm randomized, double-blind, placebo-controlled clinical trial evaluating the effects of 3.5 g and 7 g resistant potato starch (RPS) doses or placebo was conducted. The study population (n = 70) were healthy adults aged 18-69 years old living in and around Guelph, ON. Participants evaluated their stools using the Bristol Stool Chart and also recorded any ABS daily. The presence of ABS was compared between treatment arms at baseline and changes in ABS were compared within treatment arms over 1- and 4-week periods. Pearson correlation analysis was used to identify significant relationships between changes in ABS and changes in bacterial taxa.

Results: Abdominal pain, belching, bloating, constipation, diarrhea, gas, and feeling unwell were reported by participants at low levels at baseline. Neither RPS nor placebo had significant effects on mean ABS scores. However, we identified positive correlations between treatment-dependent changes in symptoms and changes in Granulicatella, Haemophilus, Lachnospira, Olsenella, Papillibacter, Turicibacter, unclassified Enterobacteriaceae, unclassified Fusobacteriaceae, unclassified Pasteurellaceae, and unclassified Gammaproteobacteria. We also identified negative correlations between treatment-dependent changes in symptoms and changes in Anaerotruncus, Dorea, RFN20, Victivallis, unclassified Coriobacteriaceae, and unclassified Oxalobacteraceae. These Pearson correlations were significant after correction for repeated testing. The mean relative abundance of these taxa did not change in response to treatment. Finally, macronutrient intake was unaffected by RPS or placebo treatments.

Conclusion: Changes in ABS can be positively or negatively correlated with changes in specific gut microbiota, creating opportunities for personalized microbiome-targeted interventions to resolve ABS.

Trial registration: The trial was registered at ClinicalTrials.gov (NCT05242913) on February 16, 2022.