Dietary flavonoids may mitigate some risk for smoking-related COPD

Higher intake of dietary flavonoids may mitigate some risk for COPD in current and former smokers, according to a study published in European Respiratory Journal.

“Fruit and vegetables, as well as tea, cocoa and other plant-based foods and beverages, are dietary sources of flavonoids, which are bioactive compounds that reduce oxidative stress and systemic inflammation,” Nicola P. Bondonno, PhD, a postdoctoral research fellow at the School of Medical Health Sciences at Edith Cowan University in Perth, Australia, and colleagues wrote. “... Although epidemiological studies investigating the association between flavonoid intakes specifically and COPD are missing, there is some evidence that flavonoid intakes are favorably associated with pulmonary function parameters and less age-related decline in lung function.”

The prospective cohort study included 55,413 participants in Denmark without COPD aged 50 to 65 years at baseline (mean age, 56 years; 47.6% men). Flavonoid intakes were estimated using a food frequency questionnaire. Daily median flavonoid intake was 496 mg.

During a median follow-up of 21 years, 5,557 participants were diagnosed with COPD, of whom 4,013 were current smokers, 1,062 were former smokers and 482 were never smokers.

Participants with the highest total flavonoid intakes had a 20% lower risk for COPD compared with participants with the lowest intakes in multivariable analyses (HR = 0.8; 95% CI, 0.74-0.87). In addition, in each flavonoid subclass, researchers identified a 6% to 22% lower risk for COPD.

The researchers reported that the inverse association between flavonoid intake and risk for COPD remained among men and women, but only among current smokers (HR = 0.77; 95% CI, 0.7-0.84) and former smokers (HR = 0.82; 95% CI, 0.69-0.97), not never smokers. In addition, higher flavonoid intakes appear to have lessened the higher risk for COPD associated with smoking intensity, according to the researchers.

“While the findings of this study suggest an importance of dietary flavonoids in partially mitigating the risk of COPD in people who smoke, both current and former smokers remained at a substantially higher risk of COPD than nonsmokers, indicating that dietary modifications should be secondary to smoking cessation,” the researchers wrote.