Antioxidants may protect hearing

A new US study reports that adequate intakes of antioxidant micronutrients such as beta-carotene, vitamin C and vitamin E may contribute to better hearing.

The observational study analyzed a potential link between daily intakes of antioxidant micronutrients and hearing ability (pure tone, speech and at high frequencies) of 2,592 participants aged 20–69 years (1). The study results showed that higher intakes of beta-carotene, vitamin C, vitamin E and magnesium were asso- ciated with significantly better hearing at both speech and high frequencies, compared with low intakes. The estimated joint effects were somewhat larger than the sums of the individual effects.

The researchers concluded that increased dietary intakes of antioxidants and magnesium seem to be asso- ciated with a lower risk of hearing loss. The discovery that the formation of free radicals in the inner ear is a key factor in hearing loss suggests that antioxidants may play a preventive or therapeutic role (2). Despite biological plausibility, only a few epidemiologic studies have examined the relations between antioxidant nutrients and hearing loss, and the results are not consistent (3). Possible reasons for null findings are that dietary assessment was misclassified or did not account for long-term intake or secondly, that imprecise outcome assessments, based on self-reports were used. Furthermore, antioxidants may be most effective when working together with other nutrients.

Hearing loss is a major public health concern affecting more than 36 million people (17% of the adult popu- lation) in the United States (4). 65% of Americans over 70 years of age have hearing loss and during the past 30 years a doubling of the number of Americans with hearing loss has been noted. According to the NHANES data, 90% and 37% of Americans have usual intakes of vitamins C and E below the Estimated Average Intake (5).

1. Choi Y.-H. et al. Antioxidant vitamins and magnesium and the risk of hearing loss in the US general population. Am J Clin Nutr. Published online November 2013.
2. Darrat I. et al. Auditory research involving antioxidants. Curr Opin Otolaryngol Head Neck Surg. 2007; 15:358–363.
3. Gopinath B. et al. Dietary antioxidant intake is associated with the prevalence but not incidence of age-related hearing loss. J Nutr Health Aging. 2011; 15:896–900.
4. Schiller J. S. L. J. et al. Summary health statistics for U.S. adults: National Health Interview Survey, 2010. National Center for Health Statistics. Vital Health Stat. Washington, DC: US Department of Health and Human Services. 2012.
5. Fulgoni III V. L. et al. Foods, fortificants and supplements: Where do Americans get their nutrients? J Nutr. 2011; 141(10):1847–1854.