Vitamin D is an essential nutrient, necessary for building and maintaining healthy bone structure by promoting calcium absorption in the body. Despite its importance, vitamin D is not found naturally in many foods. Also, with populations spending less time outdoors, vitamin D obtained naturally from sunlight is likely declining. As such, vitamin D deficiency is widespread with an estimated 1 billion individuals affected worldwide. Deficiency or insufficiency can lead to bone pain/loss, fatigue, mood changes and muscle cramps.
Vitamin D levels are typically checked with a blood test called the 25-hydroxy vitamin D test, which is measured in nanograms per milliliter (ng/mL). Generally, vitamin D levels of 20-50 ng/mL are considered to be within normal limits and anything below 20 ng/mL is considered deficient.
Vitamin D and the Ear
The human inner ear structures allow for hearing, stable vision during motion (VOR), as well as orientation to gravitational force and the ability to maintain an upright posture (VSR). The inner ear structures are fluid filled, consisting of endolymph and perilymph.
The system is dependent on a specific ionic concentration in order to work efficiently and alterations in these concentrations can lead to dysfunction of the system.
Vitamin D and BPPV
The condition of benign paroxysmal positional vertigo (BPPV) is the most common cause for vertigo, accounting for 20-30% of diagnoses in a dizziness clinic. BPPV is a condition in which calcium carbonate crystals (otoconia) migrate into the semicircular canals (head turn sensors). When the affected individual moves their head, this results in movement of the otoconia. This movement stimulates the canal, which results in nystagmus and dizziness. The condition is not directly life threatening but can lead to activity limitation, higher risk for falling, and reduced productivity. BPPV can be readily treated with a series of timed head movements referred to as canalith reposition procedures; however, the recurrence rate is high. BPPV recurrence is problematic as there is no way of knowing when someone’s symptoms might recur and there is little that can be done to reduce the risk of recurrence.
More recently it has been shown that vitamin D deficiency is associated with a higher risk of BPPV recurrence. The recurrence risk appears to be highest for those with severe vitamin D deficiency (< 12 ng/mL). One study showed a 70% risk of recurrence for those severely deficient in vitamin D and only a 22% chance of recurrence for those with normal vitamin D levels.
This would seem logical as the otoconia are made of calcium and vitamin D helps the body absorb calcium. One can speculate that if the body is better at absorbing calcium, then any otoconia that are shed should be more readily re-absorbed.
The good news is that it appears that vitamin D supplementation can reduce this risk for those that are deficient. One study showed that only 20% of participant’s experienced BPPV recurrence at 6 month follow up after supplementing vitamin D, while 100% of those that did not supplement vitamin D experienced symptom recurrence. Another study showed a less pronounced but similar pattern with 25% risk of recurrence at 1 year follow up without vitamin D supplementation, while none of the individuals in this study experienced symptom recurrence after beginning vitamin D supplementation.
In addition to these single studies, there was a meta-analysis completed in 2021 and a systematic review completed in 2022, both of which agree that vitamin D deficiency does increase recurrence risk and that supplementation is effective in reducing BPPV recurrence risk.
Vitamin D and Hearing
Vitamin D deficiency has been correlated with increased rates of sensorineural hearing loss across the lifespan. Vitamin D deficiency has been reported as a likely metabolic cause of sensorineural hearing loss dating back to the 1980’s.
A recent study showed that vitamin D deficiency during childhood was shown to result in significantly higher odds of sensorineural hearing loss. In this study, 53% of children with vitamin D deficiency had some degree of hearing loss, while CDC data suggests that less than 1% of children have hearing loss in the general population.
Vitamin D deficiency has also been shown to increase the odds of sensorineural hearing loss in adults. One study showed that the odds of bilateral hearing loss were increased by 45% in older adults when compared to their peers with normal vitamin D levels.
Some of the available literature suggests that those with vitamin D deficiency are most at risk for low frequency/pitch hearing loss.
One small scale study showed even more subtle changes in cochlear function with decreased otoacoustic emissions (OAE) in individuals with deficiency in vitamin D. This study included a population of women in their 30’s, suggestive that vitamin D deficiency may alter cochlear function, resulting in OAE abnormalities, which can precede changes on the pure tone hearing test. It should be noted that this study had a relatively small sample size.
Vitamin D deficiency has also been associated with higher rates of sudden sensorineural hearing loss as well as higher rates of hearing loss in a diabetic population. The good news is that it has also been shown that higher vitamin D intake can result in a reduced odds of hearing loss.
This is not meant as an exhaustive review of all of the potential adverse effects of vitamin D deficiency, but rather as a simple review to shed light on some of the potential complications of vitamin D deficiency on ear function. Preventative healthcare is one of the best means of reducing the physical and financial burdens of a disorder.
Vitamin D deficiency can be readily treated by a medical provider with limited risk. At this time there is at least some data to support that vitamin D supplementation may help reduce BPPV recurrence risk and reduce the risk of hearing loss.
It may be worth getting your vitamin D levels checked if you have unexplained hearing loss or if you experience recurrent BPPV symptoms.