Modulating the Gut–Lung Axis via Multi-Strain Probiotic Supplementation in Patients with Chronic Obstructive Pulmonary Disease: A Randomized Controlled Trial

People living with Chronic Obstructive Pulmonary Disease (COPD) endure relentless airway inflammation and frequent disease flare-ups. Mounting clinical evidence points to a vital, bidirectional conversation between the digestive tract and the respiratory system—known as the gut-lung axis. When the gut microbiome falls into dysbiosis, the loss of key microbial metabolites like short-chain fatty acids (SCFAs) can spill over into systemic inflammation, worsening lung injury. This study was conducted to explore whether daily oral supplementation with a high-potency multi-strain probiotic could restore microbial balance, calm systemic inflammation, and ultimately shield patients with moderate-to-severe COPD from acute exacerbations over a full year. In a 12-month, multi-center, double-blind, randomized controlled trial, 240 patients with stable COPD (GOLD Grade II–III) were randomly assigned (1:1) to receive either a daily multi-strain probiotic (Lactobacillus rhamnosus GG, Bifidobacterium animalis subsp. lactis BB-12, and Lactobacillus plantarum at 1 x 1010 CFU/day) or a matching placebo. We tracked annual acute exacerbation (AECOPD) rates, spirometry metrics (FEV1, FVC), circulating inflammatory cytokines (IL-6, TNF-alpha), fecal/serum SCFA profile via gas chromatography-mass spectrometry, and stool bacterial diversity using 16S rRNA gene sequencing. Over 52 weeks, patients receiving the probiotic experienced significantly fewer acute exacerbations compared to those on placebo (0.67 vs 1.85 events per patient-year; incidence rate ratio [IRR] = 0.36, 95% CI: 0.24–0.54, p < 0.001). Probiotic therapy led to a pronounced drop in serum IL-6 (-4.12 pg/mL vs +0.85 pg/mL, p < 0.001) and a substantial increase in total fecal SCFAs (+24.2 μmol/g vs -2.8 μmol/g, p < 0.001). Furthermore, spirometric decline in FEV1 was noticeably attenuated in the active arm (+1.2% predicted vs -2.8% predicted, p = 0.004). Targeted oral probiotic intervention effectively nurtures the gut-lung axis, blunts systemic cytokine cascades, boosts protective SCFA production, and significantly reduces disease exacerbations in stable COPD.