Introduction Higher flavonoid intakes are beneficially associated with pulmonary function parameters;
however, their association with chronic obstructive pulmonary disease (COPD) is unknown. This study
aimed to examine associations between intakes of 1) total flavonoids, 2) flavonoid subclasses and 3) major
flavonoid compounds with incident COPD in participants from the Danish Diet, Cancer and Health study.
Methods This prospective cohort included 55 413 men and women without COPD, aged 50–65 years at
recruitment. Habitual flavonoid intakes at baseline were estimated from a food frequency questionnaire
using Phenol-Explorer. Danish nationwide registers were used to identify incident cases of COPD.
Associations were modelled using restricted cubic splines within Cox proportional hazards models.
Results During 23 years of follow-up, 5557 participants were diagnosed with COPD. Of these, 4013 were
current smokers, 1062 were former smokers and 482 were never-smokers. After multivariable adjustments,
participants with the highest total flavonoid intakes had a 20% lower risk of COPD than those with the
lowest intakes (quintile 5 versus quintile 1: HR 0.80, 95% CI 0.74–0.87); a 6–22% lower risk was
observed for each flavonoid subclass. The inverse association between total flavonoid intake and COPD
was present in both men and women but only in current smokers (HR 0.77, 95% CI 0.70–0.84) and
former smokers (HR 0.82, 95% CI 0.69–0.97), not never-smokers. Furthermore, higher flavonoid intakes
appeared to lessen, but not negate, the higher risk of COPD associated with smoking intensity.
Conclusion Dietary flavonoids may be important for partially mitigating the risk of smoking-related
COPD. However, smoking cessation should remain the highest priority