Microbiome Composition and Relationships Among Glycemic Responses Following Resistant Starch Intake from Potatoes

Abstract

Abstract Objectives We explored the relationship between microbiome α-diversity and relative abundance (RA) of resistant starch (RS)-degrading bacteria and glycemic responses following the intake of Russet potatoes with varying amounts of RS. Methods Healthy females who were overweight consumed 250gm of hot (∼8.5 gm RS) or cold potatoes (∼10.8 gm RS) in a randomized crossover study. Stool was collected prior to the intervention and microbiomes were profiled using 16S rRNA gene sequencing. Only bacterial genera prevalent in ≥ 50% of subjects were included. Diet journals were collected for 10 days. Participants had postprandial blood drawn at 15, 30, 60, & 120 min following the potatoes for glucose, insulin, glucose-dependent insulinotropic peptide (GIP), and glucagon-like peptide-1 (GLP-1) analysis. “Responders” to RS were those with a ≥ 20% reduction (mean % difference) in area under the curve (AUC) of insulin following cold vs hot potatoes. Insulin was chosen because it had the most pronounced change among the biomarkers. Spearman's correlation identified relationships between bacteria and the diet and glycemic responses. Wilcoxon signed rank test compared data between Responder groups. Linear mixed models assessed glycemic responses over time. Results Thirty subjects (29.6 ± 6.0 y, BMI 32.8 ± 3.7 kg/m2) completed the study. There were significant reductions in AUC insulin and GIP across the interventions following the cold potato compared to the hot potato: P = 0.012, partial ŋ2 = 0.213 (insulin) and P < 0.0001, partial ŋ2 = 0.875 (GIP). No differences in glucose or GLP-1 were found. Shannon α-diversity score negatively correlated with mean dietary fat (r = -0.776, P < 0.0001) and positively correlated with % kilocalories from carbohydrates and insoluble fiber (r = 0.568, P = 0.001 & r = 0.527, P = 0.003, respectively). Responders (59%) to increased RS intake only differed in the RA of Subdoligranulum (P = 0.011), a butyrate-producing bacterium. Conclusions Most participants responded to RS resulting in lower AUC insulin. Several Ruminococcaceae genera correlated with AUC GIP or GLP-1 following both potatoes, which may glean insight on potential mechanisms that affect insulin response following cold or hot potatoes with varying amounts of RS. Funding Sources The Alliance for Potato Research and Education and the university's Small Grant Program.