Mice genetically engineered to lack the mitochondrial proapoptotic protein Bak were shown to be less likely to develop age-related hearing loss (AHL) than wild-type mice, thanks to reduced rates of programmed cell death in the cochlea.

The researchers concluded that cell death, mediated by the Bak protein in response to free radical damage caused by oxidative stress, is responsible for AHL.

Can dietary supplements prevent hearing loss?
The study also found that antioxidant treatment reduced onset of AHL in mice, by suppressing expression of the Bak protein in cochlear hair cells.

Lead researcher Tomas Prolla, professor of genetics at the University of Wisconsin-Madison, said that this suggested that oral antioxidants could help prevent hearing loss.

'One of the most surprising findings was that these two - alpha lipoic acid and coenzyme Q10 - were very specific in their protection against apoptosis and hearing loss,' he said.

Another researcher on the study, professor Christiaan Leeuwenburgh, of the University of Florida's college of medicine, agreed: 'It looks like a viable biological target that may be applicable to drug use.

'The issue is always timing - when to start antioxidant interventions at what combination and what dose.'

What do other researchers think?
Professor Andy Forge, of the UCL Ear Institute in London, who is an adviser to the charity Deafness Research UK, said: 'This is perhaps the most comprehensive evidence to date to support previously proposed hypotheses that hair cell death with ageing is triggered by excessive free radicals.'

But he warned that antioxidant supplements may not work in preventing hearing loss.

'The body normally takes what it needs from nutrition and additional supplementation may not be absorbed. Eating properly may be the best way to preserve hearing'.

• PNAS Online 2009

Informing Patients

• A key protein in the development of age-related hearing loss in mice has been identified for the first time.
• This could lead to new treatments to prevent hearing loss.
• More research is needed to confirm these results.