Animal study shows that common nutrients may protect hearing

February 25, 2009

Antioxidant-rich supplements may reduce the damage caused to hearing by noise and perhaps even age-related hearing loss according to promising results from animal studies. According to the National Institute on Deafness and Other Communication Disorders, about 26 million Americans have noise-induced hearing loss. The new studies using guinea pigs and mice found that supplements of beta carotene and vitamins C and E, and the mineral magnesium consumed prior to exposure to loud noise could prevent both temporary and permanent hearing loss in the 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 researcher Colleen Le Prel, an associate professor at the University of Florida.  

In the first study Guinea pigs were supplemented with the nutrients, and then the animals were exposed to four-hours of 110 decibel (dB) noise. Such levels are similar to those reached at a loud concert. Animals who consumed the vitamins did not suffer from temporary hearing loss, reported the researchers.  

In the second study, the researchers looked at the effects of a single loud sound exposure which would lead to permanent hearing loss. In this case, the vitamin supplements are reported to prevent cell loss in an inner ear structure called the lateral wall. This structure is linked to age-related hearing loss, and the researchers suggest this has implications for protecting against age-related changes in hearing in humans.  

The findings appear to fit with earlier findings that noise-induced hearing loss is linked to the production of free radicals. “The free radicals literally punch holes in the membrane of the cells,” explained Miller, from the University of Michigan. The researchers from the universities of Florida, Michigan, and Washington, and OtoMedicine reported their findings yesterday at the Association for Research in Otolaryngology’s annual conference in Baltimore.  

Note: previously, researchers from the Netherlands reported that folic acid may prevent age-related hearing loss in older men and women (Annals of Internal Medicine, 2007, Vol. 146. Researchers from the armed forces have shown that NAC and ALCAR also help protect hearing. Likewise, Vinpocetine and ALA demonstrate ability to protect hearing.