Vitamin B12 and Hearing: What Do the Scientific Findings Say?

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Vitamin B12 (cobalamin) is an essential nutrient of critical importance for general health. It plays a crucial role in the body's metabolic functions, DNA synthesis, and the sustainability of the hematopoietic system. It is also necessary for myelin sheath synthesis (myelination) in the central nervous system. Vitamin B12 deficiency is generally defined by a drop in serum or plasma B12 levels below 148 pmol/L (200 pg/mL).

Mechanisms of Connection with Hearing Loss

Vitamin B12 deficiency is associated with hearing loss, specifically through myelination disorders in cochlear nerve neurons, impaired neural transmission, and metabolic disruptions in vascular structures.

A systematic review has revealed that the prevalence of hearing impairment in individuals with low serum B12 levels is significantly higher compared to individuals with normal or high B12 levels. While some studies observed increases in hearing thresholds at low frequencies (250–500 Hz), others reported effects at high frequencies above 4 kHz. Furthermore, a decrease in Distortion Product Otoacoustic Emission (DPOAE) responses in individuals with B12 deficiency indicates functional impairment at the cochlear level.

Effects in Childhood

During childhood, B12 deficiency can adversely affect the development of the auditory system. Mild hearing loss, in particular, has been reported more commonly in school-aged children with B12 deficiency. This situation underscores the importance of early diagnosis and intervention for developmental outcomes.

Findings in the Geriatric Population

Age-related hearing loss is common in the geriatric population, and B12 deficiency is considered an accelerating factor in this process. Low serum folate and B12 levels have been shown to be significantly associated with increased hearing thresholds at high frequencies. Therefore, maintaining optimal B12 levels in older adults stands out as a potentially modifiable risk factor in preventing age-related hearing loss.

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Noise-Induced Hearing Loss and Tinnitus

In individuals with noise-induced hearing loss, significantly lower average serum B12 levels have been reported compared to control groups. Similarly, the prevalence of low B12 levels was found to be higher in individuals with tinnitus (ringing in the ears). In cases where chronic tinnitus and noise-induced hearing loss co-occur, the rates of B12 deficiency are higher than in individuals with only noise-induced hearing loss or normal hearing. Although some studies have reported that B12 supplementation alleviates tinnitus symptoms (severity, discomfort in noisy environments, subjective perception), these improvements generally do not reach statistical significance. This indicates that the therapeutic effects of B12 have not yet been clarified and that further research is needed.

Future Recommendations

More scientific research is needed to better understand the relationship between Vitamin B12 levels and hearing health and to determine the effectiveness of interventions aimed at compensating for the deficiency. In particular, longitudinal, controlled studies evaluating the effects of dietary supplements and pharmacological B12 applications on the auditory system will fill the knowledge gap in this area.

Source: Rodrigues J, Anand S, Gunjawate D, Kumar K, Ravi, R. (2025) Exploring the intricate connection between vitamin B12 deficiency and hearing loss: A systematic literature review. Ear Nose Throat J.