Antioxidant vitamins and magnesium and the risk of hearing loss in the US general population.
Level 4 - case-series / case-control
Cross-sectional analysis of NHANES survey data
PubMed 24196403 · doi:10.3945/ajcn.113.068437
What was done
Cross-sectional analysis of 2,592 US adults aged 20–69 years from NHANES 2001–2004. Researchers evaluated dietary intake of antioxidant vitamins (beta-carotene, vitamin C, and vitamin E) and magnesium in relation to pure tone averages (PTAs) measured at speech frequencies (0.5, 1, 2, and 4 kHz) and high frequencies (3, 4, and 6 kHz), adjusting for potential confounders and assessing joint nutrient interactions.
What was found
Higher individual intakes of beta-carotene, vitamin C, and magnesium (modeled as quartiles) were associated with lower (better) PTAs at both speech and high frequencies. High intakes of both beta-carotene and magnesium compared with low intakes of both were associated with a -14.82% lower PTA at high frequencies (95% CI: -20.50% to -8.74%). High intakes of both vitamin C and magnesium compared with low intakes of both were associated with a -10.72% lower PTA at high frequencies (95% CI: -16.57% to -4.45%). Joint effects were borderline significantly larger than the sum of individual effects (P-interaction = 0.08 for beta-carotene + magnesium; P-interaction = 0.09 for vitamin C + magnesium).
Why it matters
This study provides human population-level evidence supporting animal findings that combined intake of antioxidant vitamins and magnesium is associated with better hearing thresholds.
Limits
The cross-sectional design cannot establish causality or determine the temporal sequence between nutrient intake and hearing loss. Dietary intake was self-reported and subject to recall bias, and unmeasured confounders such as lifetime noise exposure may persist.