Understanding the Dynamics of Gut Microbiota Composition and Function Following Short-Term Resistant Starch Supplementation

OBJECTIVES: Increased dietary fiber intake is recommended as a potential gut microbiota-targeted nutritional strategy to reduce the risk of metabolic diseases. However, individuals’ gut microbiome composition can change differently in response to specific dietary fibers. The objective of this study is to assess, through a resistant starch intervention, the factors that could be responsible for this heterogeneity in gut microbial alterations such as baseline gut microbiota and usual dietary fiber intake. METHODS: Healthy adults (n = 75) were enrolled in a 7.5-week randomized crossover dietary intervention study consisting of three 10-day treatment periods during which they consumed resistant starch type 2 (RS2), resistant starch type 4 (RS4), or a control digestible starch, in the form of crackers. The three treatment periods were separated by 5-day washouts with no cracker consumption. We performed 16S rRNA gene sequencing on fecal samples to characterize the gut microbiota, and measured fecal short-chain fatty acids (SCFA) and bile acids. We used QIIME2 to identify amplicon sequence variants (ASVs) in the 16S rRNA sequence data, MaAsLin2 to evaluate the effect of predictor variables on differential abundances of microbes, and linear mixed models to analyze changes in fecal SCFA and bile acids. RESULTS: We found significant changes in microbial composition after RS consumption but not after the control. Specifically, six ASVs were enriched including R. bromii and F. prausnitzii, which have been associated with butyrate production, after RS2 but not after RS4. Twelve ASVs increased after RS4, including Parabacteroides distasonis, which has been shown to be associated with protection against diseases like type 2 diabetes. There were no ASVs that significantly differed after the control. For all reported significant findings, q < 0.05. CONCLUSIONS: A short-term RS intervention resulted in RS type-specific gut microbial composition changes in healthy individuals. Ongoing analyses will further evaluate the predictors of gut microbiome changes in response to RS consumption by incorporating usual dietary intake, baseline gut microbiome composition, and host genetics. FUNDING SOURCES: NIH NIDDK T32 Award and the President's Council of Cornell Women.