Disruption of the gut microbiota in kidney transplant recipients has been linked to an increased risk of post-transplant infections and gastrointestinal symptoms, including diarrhoea. Dietary supplementation with resistant starch may mitigate these risks by promoting the growth of commensal gut bacteria that produce beneficial bioactive metabolites.

Faecal microbiome profiles, gastrointestinal symptoms, and dietary habits were assessed in 13 individuals with kidney failure before and after transplantation, using 16S rRNA V4 amplicon sequencing, a modified Gastrointestinal Symptom Rating Scale (mGSRS) and a food frequency screener. The effect of resistant starch supplementation on the gut microbiota pre- and post-transplant was evaluated using a preclinical in vitro fermentation model with high amylose maize starch.

Gut microbiota diversity (based on richness and Shannon diversity index) declined significantly following kidney transplantation. This loss correlated with a higher frequency of gastrointestinal symptoms, including rectal pain. Significant shifts in microbiota composition were observed, including depletion of butyrate-producing Lachnospiraceae species, a change previously associated with post-transplant diarrhoea. These microbiota changes occurred independently of dietary patterns, which remained consistent throughout the study. Fermentation of high amylose maize starch in vitro by pre- or early post-transplant gut microbiota did not result in significant expansion of commensal bacterial populations.

Alterations in the gut microbiota following kidney transplantation are associated with gastrointestinal symptoms. High amylose maize starch supplementation did not produce beneficial effects on the gut microbiota in preclinical model studies, either before or after transplantation.