Purpose
To evaluate the association between flavonoid intake and incident primary open‐angle glaucoma (POAG).
Methods
We followed 65 516 women from the Nurses’ Health Study (from 1984) and 42 156 men from the Health Professionals Follow‐up Study (from 1986) biennially to 2012, who were 40+ years old, free of POAG, and reported eye examinations. Dietary flavonoid intake was assessed with validated repeated semi‐quantitative food frequency questionnaires. Incident POAG cases (n = 1575) were confirmed with medical record review. Cohort‐specific multivariable‐adjusted relative risks (RRs) and 95% confidence intervals (CIs) were calculated and meta‐analysed.
Results
Total flavonoid intake was not associated with risk of POAG development [RR for highest (Q5: median ~645 mg/day) versus lowest quintile (Q1: ~130 mg/day) = 0.91 (95% CI = 0.77, 1.08); p for trend (p‐trend) = 0.19]; the flavonoid subclasses of flavones, flavanones, polymeric flavanols or anthocyanidins were also not associated (Q5 versus Q1 comparison p‐values ≥0.05 and p‐trend ≥0.09). Higher intakes of flavonols and monomeric flavanols were nominally associated with lower POAG risk, based on the Q5 versus Q1 comparisons or p‐trends. The Q5 versus Q1 comparison RRs were: for flavonols, 0.82 (95% CI = 0.69, 0.97; p‐trend = 0.05; ~28 versus ~8 mg/day), and for monomeric flavanols, 0.86 (95% CI = 0.72, 1.02; p‐trend=0.04; ~110 versus 10 mg/day). The food/beverage that contributed most to both the variation of flavonols and monomeric flavanols was tea; consuming ~2 cups/day was associated with 18% lower POAG risk (RR=0.82; 95% CI = 0.68, 0.99; p‐trend = 0.02).
Conclusion
Total flavonoid intake was not associated with POAG risk. Greater intakes of flavonols and monomeric flavanols and of tea showed suggestive modest associations with lower risk; these results need confirmation.