Carotenoids, vitamin A, vitamin C, vitamin E, and folate and risk of self-reported hearing loss in women

Background: Higher intake of certain vitamins may protect against cochlear damage from vascular compromise and oxidative stress, thereby reducing risk of acquired hearing loss, but data are limited. Objective: We prospectively examined the relation between carotenoids, vitamin A, vitamin C, vitamin E, and folate intake and risk of self-reported hearing loss in women. Design: This prospective cohort study followed 65,521 women in the Nurses' Health Study II from 1991 to 2009. Baseline and updated information obtained from validated biennial questionnaires was used in Cox proportional hazards regression models to examine independent associations between nutrient intake and self-reported hearing loss. Results: After 1,084,598 person-years of follow-up, 12,789 cases of incident hearing loss were reported. After multivariable adjustment, we observed modest but statistically significant inverse associations between higher intake of beta-carotene and beta-cryptoxanthin and risk of hearing loss. In comparison with women in the lowest quintile of intake, the multivariable-adjusted RR of hearing loss among women in the highest quintile was 0.88 (95% CI: 0.81, 0.94; P-trend < 0.001) for beta-carotene and 0.90(95% CI: 0.84, 0.96; P-trend <0.001) for beta-cryptoxanthin. In comparison with women with folate intake 200-399 mu g/d, very low folate intake (<200 mu g/d) was associated with higher risk (RR: 1.19; 95% CI: 1.01, 1.41), and higher intake tended to be associated with lower risk (P-trend = 0.04). No significant associations were observed for intakes of other carotenoids or vitamin A. Higher vitamin C intake was associated with higher risk; in comparison with women with intake <75 mg/d, the RR among women with vitamin C intake >= 1000 mg/d (mainly supplemental) was 1.22 (95% CI: 1.06, 1.42; P-trend = 0.02). There was no significant trend between intake of vitamin E intake and risk. Conclusion: Higher intakes of beta-carotene, beta-cryptoxanthin, and folate, whether total or from diet, are associated with lower risk of hearing loss, whereas higher vitamin C intake is associated with higher risk.