# Site-Specific Gut Microbiome Changes After Roux-en-Y Gastric Bypass in Rats: Effects of a Multicomponent Bovine Colostrum-Based Complex

## TL;DR

This study shows how Roux-en-Y gastric bypass surgery changes gut bacteria in rats and how a colostrum-based supplement affects these changes differently in various gut regions.

## Contribution

The study reveals site-specific microbiome responses to a multicomponent supplement after gastric bypass surgery in rats.

## Key findings

- RYGB surgery caused regional gut microbiome changes, including reduced diversity and increased Proteobacteria.
- CHJ supplementation restored some beneficial bacteria but also promoted harmful ones in different gut regions.
- Serum vitamin B1 levels dropped despite increased thiamine pathway activity, showing absorption issues.

## Abstract

Roux-en-Y gastric bypass (RYGB) surgery induces profound gut microbiota alterations that may impact metabolic outcomes. This study investigated site-specific effects of a multicomponent bovine colostrum-honey-serviceberry (CHJ) complex on post-RYGB microbiome changes in obese rats. Twenty-nine Wistar rats underwent RYGB surgery with CHJ supplementation, followed by mucosal-associated microbiota analysis from five gastrointestinal segments using 16S rRNA sequencing and serum metabolite profiling. RYGB caused regional-specific changes: decreased alpha diversity, systematic Proteobacteria increases (31.2 ± 5.1% in duodenum), and reductions in SCFA-producing bacteria (Romboutsia, Roseburia). CHJ supplementation exhibited dual effects on the microbiome: restoration of beneficial bacteria (Lactobacillus, Bifidobacterium) in distal segments while concurrently promoting Enterobacteriaceae growth in proximal regions. CHJ also maintained alpha diversity levels of the mucosa-associated microbiota comparable to those observed in the control group. Disconnects emerged between predicted microbial functions and systemic metabolites: thiamine pathway activation accompanied 78.5% serum vitamin B1 reduction, indicating severe absorption deficits. Three distinct patterns emerged: pro-inflammatory (proximal), decolonization (widespread Helicobacteraceae loss), and restorative (selective CHJ-mediated recovery). Results demonstrate that post-RYGB dysbiosis exhibits profound regional heterogeneity requiring segment-specific interventions and highlight complex interactions between nutritional supplementation and surgically altered gut ecology in determining metabolic outcomes.