Green tea (Camellia sinensis) has been traditionally consumed for its general health benefits, but recent research has explored its potential in supporting respiratory health, including Chronic Obstructive Pulmonary Disease (COPD). The scientific rationale is primarily attributed to its high content of polyphenols, especially epigallocatechin gallate (EGCG), which exhibit potent antioxidant and anti-inflammatory properties. Oxidative stress and chronic inflammation are central to the pathophysiology of COPD, and compounds that mitigate these processes may offer therapeutic benefits.

Several preclinical studies have shown that green tea polyphenols can reduce inflammation and oxidative damage in lung tissues, potentially slowing the progression of COPD. A few small observational studies and cross-sectional surveys have found an association between green tea consumption and improved lung function or reduced risk of COPD, particularly in Asian populations where green tea intake is common. However, robust clinical trials directly evaluating green tea or its extracts as a treatment for COPD are limited, and the existing human evidence is mostly indirect or preliminary.

In summary, while there is scientific interest and some supportive mechanistic and observational data, the clinical evidence for green tea's efficacy in treating or managing COPD is weak at present. Therefore, its use is best considered as complementary and not a substitute for established medical therapies.