Combat sports athletes frequently experience gastrointestinal disturbances during pre-competition weight management. This study aimed to investigate the effects of probiotic supplementation on gut barrier function in combat athletes undergoing rapid weight loss prior to competition. Twenty-four elite male athletes were randomized to receive either a complex sports probiotic (1.5×10^10 CFU, twice daily) or placebo for 4 weeks. Results showed that probiotic supplementation significantly reduced gastrointestinal symptoms and gut permeability markers (Zonulin, intestinal fatty acid-binding protein, D-lactate), increased secretory immunoglobulin A (SIgA) levels, and attenuated systemic inflammation compared to placebo. The intervention enriched beneficial butyrate-producing bacteria (Blautia, Latilactobacillus) while suppressing pathogenic Streptococcus. These findings demonstrate that probiotic supplementation serves as a safe, effective nutritional strategy to maintain gut homeostasis during rapid weight loss in combat athletes.
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