Can NMN Help Protect Your Hearing? New Research Suggests Potential Benefits for Age-Related Hearing Loss

[Higlights]

•        Older mice exhibited significantly greater hearing loss compared to younger mice.

•        NMN supplementation improved NAD⁺ metabolism and may help slow age-related hearing loss (ARHL).

Age-Related Hearing Loss

One of the most common challenges associated with aging is a gradual decline in hearing.

Reduced hearing can make conversations more difficult, contribute to social isolation, and has been identified as an important risk factor for cognitive decline and dementia. Numerous epidemiological studies have reported that older adults with hearing impairment tend to experience faster cognitive decline and an increased risk of developing dementia.

Although age-related hearing loss (ARHL) is not life-threatening, it can significantly reduce quality of life. Despite its prevalence, there is currently no established treatment capable of preventing or reversing age-related hearing loss.

Like humans, mice also experience hearing decline as they age. Researchers commonly evaluate hearing using the Auditory Brainstem Response (ABR) test, which measures the brain's electrical activity in response to sound.

Young mice respond to relatively soft sounds, whereas older mice require louder sounds to produce the same response, indicating a decline in hearing sensitivity.

▲ Age-Related Hearing Loss in Older Mice

Compared with young mice (white), aged mice (gray) required significantly higher sound intensities to elicit auditory brainstem responses (ABR) across multiple frequencies, demonstrating age-related hearing impairment.

Why NMN?

NMN (Nicotinamide Mononucleotide) is a natural precursor to NAD⁺, a coenzyme essential for cellular energy production and numerous biological processes associated with healthy aging.

NAD⁺ levels naturally decline with age and have been linked to various age-related conditions. Increasing NAD⁺ levels has therefore become an important area of longevity research.

A recent study conducted by Wellness Science Labs (Japan) investigated whether NMN supplementation could help preserve hearing in an aging mouse model.

How Did NMN Affect Hearing?

 <Study Highlights>

Researchers administered 500 mg/kg of NMN daily for 13 weeks and observed:

• Slower progression of age-related hearing loss
• Increased NAD⁺ levels in the inner ear
• Changes in genes involved in ion metabolism
• Reduced oxidative stress within cochlear tissue

These findings suggest that NMN may help support healthy hearing during aging by improving cellular metabolism in the inner ear.

<Study Design and Results>

Previous studies demonstrated that Nicotinamide Riboside (NR), another NAD⁺ precursor, could help protect against hearing decline.

Researchers therefore investigated whether NMN could produce similar benefits.

Experimental Design

• Animals: 12-week-old C57BL/6J mice
• Treatment: 500 mg/kg NMN administered daily for 13 weeks
• Comparison: Control group (water only) vs. NMN-treated group

Results

As expected, mice receiving only water experienced progressive hearing loss as they aged.

In contrast, mice supplemented with NMN maintained significantly better hearing sensitivity and responded to lower sound intensities than untreated animals of the same age.

These findings indicate that NMN supplementation slowed the progression of age-related hearing loss in this animal model.

▲ NMN Reduced Age-Related Hearing Loss

Compared with aged control mice (gray), aged mice receiving NMN (red) required lower sound intensities to elicit auditory brainstem responses (ABR), particularly at 32 kHz, suggesting improved hearing sensitivity.

Proper hearing depends on maintaining a healthy balance of ions within the inner ear.

Minerals such as iron and zinc play essential roles in converting sound vibrations into electrical signals.

With aging, disruption of ion homeostasis increases oxidative stress, leading to cellular damage and gradual hearing decline.

Researchers found that NMN altered gene expression within the cochlea, particularly genes involved in metal ion metabolism.

These changes may help maintain inner ear homeostasis, reduce oxidative stress, and support healthy cochlear function.

In other words, NMN supplementation appeared to improve the cellular environment within the cochlea, potentially helping preserve hearing during aging.

Conclusion

It is important to note that this study was conducted in mice, and the same effects have not yet been confirmed in humans.

Nevertheless, the findings suggest that NMN supplementation may represent a promising strategy for supporting healthy hearing during aging by restoring NAD⁺ metabolism and protecting inner ear function.

As additional human research becomes available, NMN may emerge as an important nutritional approach for promoting healthy hearing and overall healthy aging.

[Source]

Hattori K, Hamaguchi T, Azuma-Suzuki R, Higashi S, Manji A, Morifuji M. Administration of nicotinamide mononucleotide suppresses the progression of age-related hearing loss in mice. Hear Res. 2025 Mar;457:109182. doi: 10.1016/j.heares.2025.109182. Epub 2025 Jan 5. PMID: 39778468.