Effects of functional dietary fiber supplementation combined with home-based exercise on gut microbiota diversity and low-grade inflammation in urban sedentary adults

Introduction Sedentary behavior is associated with gut microbiota dysbiosis and low-grade systemic inflammation, both of which contribute to increased cardiometabolic risk. However, the combined effects of functional dietary fiber supplementation and home-based exercise on these outcomes remain unclear. This study aimed to investigate whether a combined intervention could improve gut microbiota diversity and reduce systemic inflammation in urban sedentary adults. Methods In this 24-week parallel-group randomized controlled trial, 140 sedentary adults were randomly assigned to an intervention group (functional dietary fiber supplementation providing 15–20 g/day of resistant starch, inulin, and beta-glucan combined with home-based moderate-intensity exercise, five sessions per week) or a control group maintaining their usual lifestyle. Gut microbiota diversity was assessed using 16S rRNA gene sequencing, and inflammatory markers (hs-CRP, IL-6, TNF-α, IL-10) were measured using immunoassays. Results The intervention significantly increased gut microbiota alpha diversity, with Shannon index rising from 3.82 ± 0.48 to 4.31 ± 0.49 ( p < 0.001), while minimal changes were observed in controls. Significant reductions were observed in hs-CRP (−42.1%), IL-6 (−35.4%), and TNF-α (−28.6%), alongside an increase in IL-10 (+31.8%) (all p < 0.001). Butyrate levels increased by 50%, and changes in Shannon diversity were negatively correlated with reductions in hs-CRP ( r = −0.52, p < 0.001). Conclusion Combined functional dietary fiber supplementation and home-based exercise significantly improved gut microbiota diversity and reduced low-grade inflammation in sedentary adults. These findings support integrated lifestyle interventions as effective strategies for reducing cardiometabolic risk.