Total isoflavone intake was estimated from a validated food frequency questionnaire based on five major dietary isoflavones. Key findings include:Higher total isoflavone intake was associated with better overall COPD health status, reflected by lower COPD Assessment Test (CAT) scores. Participants with higher isoflavone intake reported significantly fewer cough and sputum clearance symptoms, as measured by ECSC scores. Higher isoflavone intake may reflect an overall healthier diet and lifestyle rather than a direct effect of isoflavones. Overall, the findings suggest that higher isoflavone intake is associated with improved respiratory health and lower platelet activation in former smokers with COPD.