Abstract
Introduction: Vitamin D deficiency may contribute to auditory dysfunction, including sudden sensorineural hearing loss (SSNHL) and age-related Hearing loss (HL). This study aimed to examine the association between vitamin D, calcium levels, and hearing impairments.
Methods: This systematic review and Meta-analysis followed PRISMA guidelines. Eligible studies were critically appraised using the Joanna Briggs Institute tools. A random-effects model was employed to account for heterogeneity across studies. Due to substantial heterogeneity, pooled estimates are interpreted cautiously as averages of widely varying effects.
Results: From 2,699 records screened, 33 studies were included in the systematic review, and 14 in the Meta-Analysis. Pooled analysis showed lower vitamin D levels in individuals with HL (standardized mean difference [SMD]=-0.687; 95% CI: -0.832 to -0.542; P<0.001; though heterogeneity was extremely high (I²=99.22%)). Subgroup analysis showed a consistent association for SNHL (SMD=-0.718; 95% CI: -0.873 to -0.564; I²=0.0%), while no significant association was found for tinnitus. Calcium levels were also low among HL patients (SMD=-0.518; 95% CI: -0.730 to -0.305; P<0.001; I²=93.79%), though findings varied by condition, with one SSNHL study reporting elevated calcium.
Conclusion: Vitamin D deficiency appears to be consistently associated with SSNHL, while evidence for tinnitus and conductive loss remains inconclusive and limited by study quality. The predominance of cross-sectional designs precludes causal inference. Future longitudinal and interventional research is needed to establish causality, clarify the role of calcium, and identify populations most likely to benefit from vitamin D screening and supplementation.