Chronic Obstr Pulm Dis
Soy isoflavones linked to lower COPD symptom burden
Clinical takeaway: Higher intake of isoflavones—found in foods such as tofu and soy milk—was associated with modest but clinically relevant improvements in COPD symptoms, suggesting dietary patterns may complement standard COPD management.
Diet is increasingly recognized as a modifiable factor in chronic lung disease, yet specific nutritional components that may influence COPD morbidity remain understudied. Isoflavones, plant‑derived compounds common in legumes, have anti‑inflammatory and antiplatelet properties that could plausibly affect COPD symptoms.
In a prospective observational study of 99 former smokers with moderate to severe COPD, higher average dietary isoflavone intake was associated with better patient‑reported respiratory outcomes over 6 to 9 months of follow‑up. Participants had a mean age of 66 years, a mean FEV₁ of 49.8% predicted, and low socioeconomic status.
After adjustment for clinical and demographic factors, higher isoflavone intake was linked to improved patient‑reported COPD symptoms. Each standard‑deviation increase was associated with a 2‑point lower COPD Assessment Test score (p=0.011), meeting the minimal clinically important difference. Smaller but significant improvements were also seen in the Clinical COPD Questionnaire and cough/sputum scores, while dyspnea and exacerbation rates were unchanged.
Although total isoflavone intake was assessed, the associations were driven largely by genistein and daidzein, the predominant soy‑derived isoflavones in human diets. Other isoflavones, typically found in red clover rather than common foods, showed weaker or no associations.
Higher isoflavone intake was also associated with a 7% reduction in urinary 11‑dehydro‑thromboxane B₂, a marker of platelet activation. This finding suggests that reduced platelet activity may be one mechanism by which isoflavone‑rich foods help improve COPD symptoms, independent of other dietary factors such as omega‑3 intake.
Higher intake of isoflavone‑rich foods was linked to better COPD health status, fewer cough and sputum symptoms, and lower platelet activation, suggesting diet may influence COPD morbidity through biologically plausible pathways, the study authors conclude.
Source: Belz DC, et al. (2026, February 23). Chronic Obstr Pulm Dis. Isoflavone intake is associated with decreased chronic obstructive pulmonary disease morbidity