Exploring the Intricate Connection Between Vitamin B12 Deficiency and Hearing Loss: A Systematic Literature Review

Background: Vitamin B12 is an essential nutrient crucial for overall health, and deficiencies can lead to hearing loss. Objective: The aim of the systematic review was to explore the intricate connection between vitamin B12 deficiency and hearing loss using a systematic literature review. Methods: A systematic literature search was carried out to identify the articles exploring the connection between vitamin B12 deficiency and hearing loss. Electronic databases such as PubMed, Scopus, and Cochrane databases were used to identify the relevant studies. Results: A total of 612 studies were identified from 3 databases, and after stepwise screening, 9 articles were found eligible for the data extraction and inclusion in the review. Most of the studies had observed statistically-significant differences in the hearing thresholds with low vitamin B12 levels. However, few studies found hearing loss in the low frequencies (250 and 500 Hz), and others have found elevated thresholds above 4 KHz. Factors such as age, gender, and treatment for vitamin B12 did not show any significant changes in the hearing thresholds. Conclusion: The systematic review revealed that individuals with lower vitamin B12 levels tended to have a higher prevalence of hearing impairment than those with normal or elevated levels. Vitamin B12 deficiency, coupled with high homocysteine levels and low folate concentrations, may contribute to different degrees of hearing loss, particularly in the elderly. Lower serum levels of vitamin B12 have been associated with slight to mild hearing loss, while cochlear dysfunction and poorer hearing thresholds have also been observed in individuals with vitamin B12 deficiency. These findings highlight the importance of maintaining optimal levels of vitamin B12 for preserving hearing health and warrant further investigation into potential interventions.