The gut and the lungs sit far apart, but a growing body of research ties the bacteria living in one to the health of the other. A 2025 meta-analysis pooling 27 studies and more than 8,000 people combined found consistent bacterial differences in the guts of people with chronic lung disease compared with healthy controls.[1]
| Bacteria | Change in COPD | Evidence |
|---|---|---|
| Bifidobacterium | Notably lower across pooled studies | Moderate |
| Lactobacillus | Also lower in COPD patients | Moderate |
| Bacteroides | Higher in COPD patients | Moderate |
| Overall diversity (Shannon index) | Reduced in COPD; no meaningful change found in asthma | Weak |
Bar length reflects the size of the statistical difference (standardized mean difference) reported for each measure.[1]
One proposed pathway starts in the gut wall itself. Reduced Firmicutes bacteria, which normally produce butyrate, appears to weaken the intestinal barrier and let bacterial fragments enter the bloodstream, triggering inflammatory signaling that reaches the lungs, a pattern with parallels in gut-heart research.[1] The review's authors suggest probiotic supplementation as a possible supportive therapy for COPD patients, alongside standard treatment, though they stop short of calling it a proven replacement for medication.
What to do with this
This research doesn't mean a probiotic can replace an inhaler or prescribed COPD treatment, and no study has shown that yet. What it does suggest is that the same fiber-rich, diverse diet, built around staples like psyllium husk, that supports Bifidobacterium and Lactobacillus levels for general gut health may be a reasonable addition alongside standard respiratory care. If you have COPD or asthma and are curious about a probiotic, bring the pooled evidence up with your pulmonologist rather than trying one on your own first.
