Contact: Jill Pease
University of Florida
Vitamin supplements may protect against noise-induced hearing loss
GAINESVILLE, Fla. — Vitamin
supplements can prevent hearing loss in laboratory animals, according
to two new studies, bringing investigators one step closer to the
development of a pill that could stave off noise-induced and perhaps
even age-related hearing loss in humans.
The findings will be
reported Wednesday at the Association for Research in Otolaryngology's
annual conference in Baltimore by senior author Colleen Le Prell,
Ph.D., a researcher at the University of Florida.
supplements used in the research studies are composed of antioxidants —
beta carotene and vitamins C and E — and the mineral magnesium. When
administered prior to exposure to loud noise, the supplements prevented
both temporary and permanent hearing loss in test animals.
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,
an associate professor in the UF College of Public Health and Health
Professions' department of communicative disorders.
million Americans have noise-induced hearing loss, according to the
National Institute on Deafness and Other Communication Disorders, the
agency that funded the studies.
In the first study, UF,
University of Michigan and OtoMedicine scientists gave guinea pigs the
vitamin supplements prior to a four-hour exposure to noise at 110
decibels, similar to levels reached at a loud concert. Researchers
assessed the animals' hearing by measuring sound-evoked neural activity
and found that the treatment successfully prevented temporary hearing
loss in the animals.
In humans, temporary noise-induced
hearing loss, often accompanied by ringing in the ears, typically goes
away after a few hours or days as the cells in the inner ear heal.
Because repeated temporary hearing loss can lead to permanent hearing
loss, the scientists speculate that prevention of temporary changes may
ultimately prevent permanent changes.
In the second, related
study in mice, UF, Washington University in St. Louis and OtoMedicine
researchers showed that the supplements prevented permanent
noise-induced hearing loss that occurs after a single loud sound
exposure. The researchers found that the supplements prevented cell
loss in an inner ear structure called the lateral wall, which is linked
to age-related hearing loss, leading the scientists to believe these
micronutrients may protect the ear against age-related changes in
"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, M.D., an associate professor of surgery
in the otolaryngology division at Duke University Medical Center. "I
look forward to hearing Dr. Le Prell's work and reviewing her data."
research builds on previous studies that demonstrated hearing loss is
not just caused by intense vibrations produced by loud noises that tear
the delicate structures of the inner ear, as once thought, said Josef
Miller, Ph.D., 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.
free radicals literally punch holes in the membrane of the cells," said
Miller, the Townsend professor of communicative disorders at the
University of Michigan.
Miller is the co-founder of
OtoMedicine, a University of Michigan spinoff company that has patented
AuraQuell, the vitamin supplement formula used in the studies.
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
Antioxidant supplements can also provide
"post-noise rescue," Le Prell said. A previous study by Le Prell and
Miller showed that antioxidants can protect hearing days after exposure
to loud noise.
"We found that the antioxidant combination of
vitamin E and salicylate — the active agent in aspirin —effectively
prevented cell death and permanent noise-induced hearing loss even when
treatments were delayed up to three days after noise insult," she said.
researchers are collaborating on National Institutes of Health-funded
clinical trials of the vitamin supplements in college students at UF
who wear MP3 music players, and noise-exposed military troops and
factory workers in Sweden and Spain.
If the trials show that
the vitamins are as effective in preventing noise-induced hearing loss
in humans as they have been in animals, Le Prell and Miller envision an
easy-to-use supplement that could come in the form of a pill for people
headed to a rock concert, a daily supplement for factory workers or a
nutritional bar included in soldiers' rations.
protection, such as ear plugs, is always the best practice for the
prevention of noise-induced hearing loss, but in those populations who
don't or can't wear hearing protection, for people in which mechanical
devices just aren't enough, and for people who may experience
unexpected noise insult, these supplements could provide an opportunity
for additional protection," Le Prell said.