Abstract
Respiratory symptoms like prolonged cough and breathlessness have increased post-COVID-19, even in those with normal chest X-rays and FEV1/FVC ratios. This study assessed the benefits of Lactobacillus plantarum GCWB1001 on such symptoms in individuals without asthma or COPD. In a double-blind, randomized, placebo-controlled trial, 126 participants aged 19-70 were included. Exclusions were for asthma, COPD, abnormal chest X-rays, or recent antibiotic use. The primary outcome was the Breathlessness, Cough, and Sputum Scale (BCSS), with secondary outcomes including Visual Analogue Scale (VAS) scores for respiratory function. The total BCSS score at 12 weeks did not differ significantly between the GCWB1001 and placebo groups. Secondary endpoints such as sputum and breathlessness showed numerical improvements, particularly in males and participants over 40, but these findings were not statistically significant after correction for multiple comparisons. No serious adverse events were reported, indicating safety. Although this study did not demonstrate a clear clinical benefit, the exploratory trends suggest that additional, larger-scale trials may be needed to determine if these observations reflect a meaningful effect.