Hearing ability naturally decreases with age. However, by taking dietary supplements containing phytosterols, it seems possible to improve the function of special sensory cells in the inner ear, which could open up new approaches to the prevention and treatment of hearing loss.
In a recent study involving experts from the Universidad de Buenos Aires, the so-called cholesterol homeostasis in the inner ear of mice was described as a new possibility for the prevention and treatment of hearing loss. The study has been published in the English-language journal “PLoS Biology”.
Why do we hear worse as we age?
Sensory cells in the inner ear, called outer hair cells (OHC), amplify sounds by changing their length. However, as we age, these cells lose their ability to stretch in response to sound, preventing sound from being amplified and leading to age-related hearing loss, the researchers report in a press release.
Cholesterol plays a key role in this stretch response. And because brain cholesterol decreases with age, the team hypothesized that the hearing loss might be related to the loss of cholesterol in the outer hair cells of the inner ear.
What role did the enzyme CYP46A1 play?
To test this hypothesis, the researchers analyzed the amount of CYP46A1 in the outer hair cells of the inner ear. CYP46A1 is an enzyme that helps break down and recycle cholesterol.
It was found that older mice had more of the enzyme in their inner ears than younger animals. As a result, there was also less cholesterol in the inner ears of older mice.
The team proceeded to prove cause and effect. For this purpose, overactivation of CYP46A1 was triggered in young mice with a drug. This produced a hearing loss that manifested itself as abnormal performance of the inner ear cells.
Link between cholesterol and hearing
Next, the experts checked whether increasing cholesterol levels in the brains of the mice could inhibit the effects of the drug. To do this, the team used plant-based cholesterol-like compounds (phytosterols), which are also found in many over-the-counter dietary supplements.
Young mice that received the CYP46A1-activating supplement but also ingested phytosterols from their diet for a period of three weeks showed improved function of the outer hair cells of the inner ear.
Better hearing through dietary supplements?
According to the researchers, dietary supplements with phytosterols could therefore be an easy way to counteract natural age-related hearing loss.
However, before any definitive conclusions can be drawn, it is first necessary to further investigate the effects of phytosterols on hearing loss, particularly directly in humans. (as)
