Associations between intake of dietary flavonoids and the 10-year incidence of tinnitus in older adults

Purpose: Dietary flavonoids are bioactive compounds that have been widely investigated for their associations with vascular health outcomes. As the development of tinnitus has been linked to vascular pathways, dietary flavonoids may have role in the prevention of tinnitus symptoms. This study reports the associations between the intakes of major classes of dietary flavonoids and 10-year incidence of tinnitus. Methods: Of the 1753 participants (aged ≥ 50 years) from the Blue Mountains Hearing Study with complete baseline data on tinnitus symptoms and dietary intakes, 536 (31%) cases of tinnitus were identified and excluded from further analysis. Dietary data was collected using a semi-quantitative food frequency questionnaire and intakes of the five major classes of flavonoids were determined using U.S. Department of Agriculture flavonoid databases. Presence of prolonged tinnitus was assessed by a positive response to a single question administered by an audiologist. Results: Of the remaining 1217 participants without tinnitus at baseline, 222 (18%) incident cases of tinnitus were identified over 10 years. After age–sex adjustment, participants in the third versus first quartile of proanthocyanidin intake were significantly less likely to develop incident tinnitus by 36% (HR = 0.64; 95% CI 0.43–0.96, P_trend = 0.04). Following multivariable adjustment, this protective trend was non-significant (HR = 0.60; 95% CI 0.39–0.92; P_trend = 0.06). Similarly, a non-significant protective trend was observed when comparing the fourth versus first quartile of intake of all flavonoids (OR = 0.61; 95% CI 0.39–0.96). No other associations were observed. Conclusion: Our findings do not support the hypothesis that dietary flavonoids are protective against the development of tinnitus over 10 years. The weak significant association observed between proanthocyanidin and incident tinnitus may be a chance finding as there was no significant trend following multivariate adjustments and, therefore, requires further studies to investigate these associations.