Common Dietary Supplements Can Reduce Age-Related Hearing Loss

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Common Dietary Supplements Can Reduce Age-Related Hearing Loss

Common Dietary Supplements Can Reduce Age-Related Hearing Loss.

Researchers from the Pharmacology Institute at the University of Buenos Aires School of Medicine, including Maria Eugenia Gomez Casati, along with Mauricio Martin from the Mercedes Medical Research Institute and Martin Ferrera from the National University of Córdoba’s INIMEC-CONICET-UNC, have uncovered a link between age-related hearing loss and decreased cholesterol levels in the inner ear.

Their recent findings, published in the journal “PLOS Biology,” suggest that plant sterol supplements can substitute for lost cholesterol, preventing sensory dysfunction in mice.

The sensory cells in the inner ear, known as outer hair cells (OHC), amplify sound by altering the length of sound waves. As individuals age, these cells lose their ability to stretch with sound, thus failing to amplify it, resulting in age-related hearing loss. Given the critical role of cholesterol in this stretching response and recent studies indicating a decrease in brain cholesterol with age, researchers hypothesized that hearing loss might be linked to a loss of cholesterol in OHCs. This hypothesis was validated in mice.

First, the researchers measured the levels of CYP46A1 in the inner ear OHCs, as this enzyme aids in cholesterol breakdown and recycling. As expected, they found that older mice had more CYP46A1 in their inner ears, leading to lower cholesterol levels. Next, they overactivated CYP46A1 with a drug, inducing hearing loss in younger mice (manifested as abnormal output from inner ear cells), thus proving a causal relationship.

Common Dietary Supplements Can Reduce Age-Related Hearing Loss

Finally, they tested whether increasing cholesterol in the brain could counteract the drug. Since cholesterol cannot enter the brain from the bloodstream, the researchers used plant sterols, plant-derived cholesterol-like compounds that can enter the brain. Mice that simultaneously received the CYP46A1-activating drug and consumed plant sterols for three weeks showed improved OHC function.

Since plant sterols are readily available in many over-the-counter supplements, they could be a convenient method for preventing age-related hearing loss. However, it is essential to directly test their impact on hearing loss in elderly mouse models and humans before drawing more definitive conclusions.

The authors added, “In this study, we found the following: 1) aging triggers cholesterol loss in inner ear sensory cells; 2) a reverse transcriptase therapy widely used to treat HIV/AIDS patients reproduces the observed cholesterol loss in older individuals and leads to impaired outer hair cell function; 3) we found that these defects can be partially reversed by supplementing with plant sterols. Our research results are highly promising as they provide the first fundamental evidence supporting the use of plant sterol supplementation as a potential approach for preventing or treating hearing loss.”