Postbiotic Intervention Improves Bowel Function and Promotes Systemic Health in Institutionalized Older Adults

Postbiotic interventions represent a promising strategy to modulate gut health, but clinical evidence in older adults is limited. This study aimed to evaluate the effects of a postbiotic supplement consisting of inactivated bacterial cells on bowel function, systemic inflammation, and gut microbiota composition in institutionalized older adults. In this randomized, double-blind intervention study, 48 older adults received either postbiotic or placebo for 8 weeks. Daily assessment of gastrointestinal manifestations, bowel movements, and laxative use were collected, alongside pre- and post-intervention hematological and clinical biochemical assessments. Postbiotic supplementation improved bowel regularity, reduced diarrheal episodes, and decreased laxative reliance, effects that paralleled reductions in systemic inflammatory markers and improvements in red blood cell parameters. These clinical and hematological changes were accompanied by a more favorable gut microbiota profile, characterized by an increase in bacterial groups associated with anti-inflammatory effects in the postbiotic group and of taxa linked to dysbiosis in the placebo group. Our findings suggest that postbiotic supplementation in institutionalized older adults promotes beneficial shifts in gut microbiota, which are associated with reduced systemic low-grade inflammation and consequent improvements in bowel function and inflammation-related anemia, indicating an integrated microbiota-mediated mechanism supporting gut and systemic health.