Vitamin B12 deficiency damages hearing by slowing nerve signals and reducing inner ear function, according to Gram Research analysis of a 2026 systematic review of 11 studies. Objective hearing tests show consistent abnormalities including delayed nerve responses and reduced inner ear activity. In children, B12 supplements partially or completely restored hearing function, though evidence in adults remains limited. Balance system effects were inconsistent across studies.
A new systematic review examined whether vitamin B12 deficiency damages hearing and balance. Researchers looked at 11 studies using specialized tests that measure how well sound travels through the ear and how the balance system works. The findings show that low B12 levels do appear to harm the nerves and inner ear structures involved in hearing, causing detectable changes on objective tests. However, the effects on balance were less clear. The good news: in babies and young children, B12 supplements helped restore some or all of their hearing function. This research suggests doctors should test hearing in people with B12 deficiency to catch problems early.
Key Statistics
A 2026 systematic review of 11 studies found that vitamin B12 deficiency consistently causes abnormal auditory brainstem response tests, indicating delayed nerve signal transmission in the hearing pathway.
In infant and child populations with B12 deficiency, vitamin B12 supplementation resulted in partial or complete recovery of auditory function, according to the 2026 systematic review published in Otolaryngology-Head and Neck Surgery.
Objective hearing tests including otoacoustic emissions showed reduced amplitudes in individuals with vitamin B12 deficiency, suggesting damage to inner ear hair cell function, the 2026 systematic review found.
Vestibular system findings were inconsistent across the 11 studies reviewed, with some reporting absent balance nerve responses while others found no significant abnormalities in balance testing.
The Quick Take
- What they studied: Whether vitamin B12 deficiency causes measurable changes in hearing and balance using objective medical tests rather than just asking patients how they feel.
- Who participated: Eleven published studies involving people with confirmed vitamin B12 deficiency. The studies used specialized hearing and balance tests to measure nerve and inner ear function.
- Key finding: Vitamin B12 deficiency consistently showed abnormal hearing test results, including delayed nerve signals and reduced inner ear responses. Balance test results were mixed and inconclusive.
- What it means for you: If you have low B12 levels, your doctor may want to check your hearing with objective tests even if you don’t notice problems yet. Early detection could prevent permanent hearing loss. B12 supplements appear to help restore hearing in children, though more research is needed in adults.
The Research Details
This was a systematic review, which means researchers searched medical databases for all published studies on this topic and carefully analyzed them together. They looked at PubMed, Scopus, Web of Science, and EMBASE databases to find relevant research. Two independent reviewers screened each study to make sure it met specific criteria: it had to measure hearing or balance using objective tests (machines that measure nerve signals and inner ear function) in people with confirmed B12 deficiency.
The researchers used a standardized tool called the Mixed Methods Appraisal Tool to evaluate the quality of each study. This helps readers understand which studies were well-designed and which had limitations. The review was registered in advance with PROSPERO, which is a database that tracks systematic reviews to prevent bias and ensure transparency.
This approach is valuable because it combines evidence from multiple studies rather than relying on a single experiment. By looking at patterns across 11 studies, the researchers could identify consistent findings about how B12 deficiency affects hearing and balance.
Vitamin B12 is essential for maintaining healthy nerves throughout your body, including the nerves involved in hearing and balance. When B12 levels drop, these nerves can malfunction. However, many people with B12 deficiency don’t realize their hearing or balance is affected because the damage happens gradually and may not cause obvious symptoms at first. Using objective tests (machines that measure nerve function directly) can catch these problems before a person notices them, which is important because hearing loss can sometimes be prevented or reversed if caught early.
This systematic review followed established scientific standards and was registered in advance, which increases its credibility. The researchers had two independent reviewers evaluate each study to reduce bias. However, the review found only 11 studies on this topic, and the studies varied in their methods and quality. Some studies were small or had design limitations. The evidence for balance problems was particularly weak and inconsistent. Readers should understand that while the hearing findings are fairly consistent, more high-quality research is needed, especially in adults.
What the Results Show
The review found strong evidence that vitamin B12 deficiency damages the hearing system. Specifically, tests called Auditory Brainstem Response (ABR) showed delayed nerve signals, meaning sound takes longer to travel from the ear to the brain. Tests measuring inner ear function, called Otoacoustic Emissions (OAE), showed reduced responses, indicating the tiny hair cells in the inner ear aren’t working properly.
These findings suggest B12 deficiency harms two parts of the hearing system: the nerves that carry sound signals and the inner ear structures that process sound. The damage appears to be subclinical, meaning it shows up on objective tests before a person notices hearing problems in daily life.
In children and infants with B12 deficiency, giving B12 supplements led to partial or complete recovery of hearing function. This is encouraging because it suggests the damage may be reversible, at least in younger people. However, the review didn’t find enough evidence to draw firm conclusions about whether supplements help adults recover hearing.
Balance system findings were inconsistent across studies. Some studies found abnormal responses in tests called cVEMP (cervical Vestibular Evoked Myogenic Potentials), which measure balance nerve function. Other studies using different balance tests found no significant problems. This inconsistency suggests either that B12 deficiency affects balance differently than it affects hearing, or that the available tests aren’t sensitive enough to detect balance problems reliably. More research is needed to clarify whether B12 deficiency truly damages the balance system.
This systematic review builds on earlier research showing that B12 deficiency can cause nerve damage throughout the body. Previous studies had suggested hearing problems might occur, but this review is the first to comprehensively examine objective test results across multiple studies. The findings align with what we know about how B12 supports nerve health: without enough B12, the protective coating around nerves breaks down, slowing nerve signals. The hearing findings are consistent with this mechanism. The inconclusive balance findings suggest that hearing nerves may be more vulnerable to B12 deficiency than balance nerves, though this needs further investigation.
The review included only 11 studies, which is a relatively small number. The studies varied significantly in their methods, populations, and quality, making it difficult to combine results. Most studies were small and some had design limitations. The review found very little research on adults; most evidence came from children and infants. There’s also a gap in research on whether B12 supplements actually improve hearing in adults with deficiency. The balance system findings were too inconsistent to draw reliable conclusions. Finally, the review couldn’t determine exactly how much B12 deficiency is needed to cause hearing problems or how long the deficiency must last.
The Bottom Line
If you have confirmed vitamin B12 deficiency, ask your doctor about hearing tests using objective measures like ABR or OAE, even if you don’t notice hearing problems. This is a moderate-strength recommendation based on consistent evidence. If you have B12 deficiency and notice hearing changes, supplementation is worth trying, especially if you’re young, though more research is needed on effectiveness in adults. For balance problems, current evidence is too weak to make specific recommendations, but mention any balance concerns to your doctor.
People with diagnosed B12 deficiency should pay attention to this research, particularly those with pernicious anemia or dietary B12 deficiency. Older adults are at higher risk for B12 deficiency and should be aware of potential hearing impacts. People taking medications that interfere with B12 absorption should also be concerned. Healthcare providers treating B12 deficiency should consider adding hearing assessments to their evaluation. This research is less relevant for people with normal B12 levels.
Hearing damage from B12 deficiency develops gradually over weeks to months, so you won’t notice changes overnight. In children receiving B12 supplements, hearing improvements appeared within weeks to months, though complete recovery took longer in some cases. In adults, the timeline for improvement with supplementation is unknown because there’s limited research. The key point: early detection through objective testing may prevent permanent damage, so don’t wait for obvious symptoms.
Frequently Asked Questions
Does vitamin B12 deficiency cause hearing loss?
Yes, research shows B12 deficiency damages hearing by affecting nerve signals and inner ear function. Objective tests consistently show abnormalities including delayed nerve responses and reduced inner ear activity. In children, B12 supplements can restore hearing, though adult recovery data is limited.
Can you reverse hearing loss from low B12?
In children and infants with B12 deficiency, hearing improvements occurred with supplementation, sometimes completely restoring function. Evidence in adults is scarce, but early detection and treatment may prevent permanent damage. The sooner deficiency is corrected, the better the potential for recovery.
What tests detect hearing problems from B12 deficiency?
Objective tests like auditory brainstem response (ABR) and otoacoustic emissions (OAE) reliably detect hearing damage from B12 deficiency before you notice symptoms. These tests measure nerve signals and inner ear function directly, catching subclinical damage early.
Does B12 deficiency affect balance?
Balance effects from B12 deficiency remain unclear. Some studies found abnormal balance nerve responses while others found none. More research is needed to determine whether B12 deficiency truly damages the balance system or if current tests simply can’t detect it reliably.
Should I get hearing tests if I have low B12?
Yes, ask your doctor about objective hearing tests like ABR or OAE if you have confirmed B12 deficiency, even without hearing symptoms. Early detection can prevent permanent damage, and B12 supplementation may help restore function, especially in younger people.
Want to Apply This Research?
- Log your B12 supplement doses and dates, then track any changes in hearing clarity or balance stability using a simple 1-10 scale weekly. Note any environmental factors that affect your hearing perception.
- If you have B12 deficiency, set a reminder to take B12 supplements consistently as prescribed. Schedule a hearing test appointment with your doctor within the next month, even if you don’t notice problems. Keep a simple log of any hearing or balance changes you notice.
- Track B12 supplement adherence daily. Every 3 months, note any subjective changes in hearing or balance. Schedule objective hearing tests annually if you have B12 deficiency, or more frequently if you notice changes. Share this tracking data with your healthcare provider to guide treatment decisions.
This article summarizes research findings and should not replace professional medical advice. If you have vitamin B12 deficiency or suspect hearing problems, consult your healthcare provider for proper evaluation and treatment. Hearing test recommendations and B12 supplementation decisions should be made with your doctor based on your individual health status. This review examined published studies but does not constitute medical diagnosis or treatment guidance.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.