Scientists have edged closer to developing a pill to stave off noise-induced or age-related hearing loss in humans, after vitamin supplements given to lab animals protected hearing.
These supplements comprise antioxidants like beta carotene and vitamins C and E - and magnesium. Given before exposure to loud noise, the supplements prevented both temporary and permanent hearing loss in test animals.
"What is appealing about this vitamin 'cocktail' is that previous studies in humans, including those demonstrating successful use of these supplements in protecting eye health, have shown that supplements of these particular vitamins are safe for long-term use," said Le Prell, associate professor at the University of Florida (UF) College of Public Health and Health Professions.
About 26 million Americans have noise-induced hearing loss, according to the National Institute on Deafness and Other Communication Disorders, the agency that funded the studies.
"I am very encouraged by these results that we may be able to find a way to diminish permanent threshold shift with noise exposure," said Debara Tucci, associate professor of surgery, otolaryngology division at Duke University Medical Centre. I look forward to hearing Dr Le Prell's work and reviewing her data."
The research builds on previous studies that demonstrated hearing loss is not just caused by intense vibrations produced by loud noises, said Josef Miller, who has studied the mechanisms of hearing impairment for more than 20 years and is a frequent collaborator of Le Prell's.
Researchers now know noise-induced hearing loss is largely caused by the production of free radicals, which destroy healthy inner ear cells, according to an UF release.
Antioxidant vitamins prevent hearing damage by "scavenging" the free radicals. Magnesium, which is not a traditional antioxidant, is added to the supplement mix to preserve blood flow to the inner ear and aid in healing.
The findings were reported on Wednesday at the Association for Research in Otolaryngology's annual conference in Baltimore.