Antioxidant vitamins and magnesium and the risk of hearing loss in the US general population.

BACKGROUND The protective effects of antioxidant vitamins on hearing loss are well established in animal studies but in few human studies. Recent animal studies suggest that magnesium intake along with antioxidants may act in synergy to prevent hearing loss. OBJECTIVE We examined associations between intake of antioxidant vitamins (daily β-carotene and vitamins C and E) and magnesium and hearing thresholds and explored their joint effects in US adults. DESIGN We analyzed cross-sectional data from 2592 participants aged 20-69 y from NHANES 2001-2004. Hearing thresholds as pure tone averages (PTAs) at speech (0.5, 1, 2, and 4 kHz) and high frequencies (3, 4, and 6 kHz) were computed. RESULTS When examined individually, modeled as quartiles, and after adjustment for potential confounders, higher intakes of β-carotene, vitamin C, and magnesium were associated with lower (better) PTAs at both speech and high frequencies. High intakes of β-carotene or vitamin C combined with high magnesium compared with low intakes of both nutrients were significantly associated with lower (better) PTAs at high frequencies (-14.82%; 95% CI: -20.50% to -8.74% for β-carotene + magnesium and -10.72%; 95% CI: -16.57% to -4.45% for vitamin C + magnesium). The estimated joint effects were borderline significantly larger than the sums of the individual effects [high β-carotene/low magnesium (-4.98%) and low β-carotene/high magnesium (-0.80%), P-interaction = 0.08; high vitamin C/low magnesium (-1.33%) and low vitamin C/high magnesium (2.13%), P-interaction = 0.09]. CONCLUSION Dietary intakes of antioxidants and magnesium are associated with lower risks of hearing loss.