Vitamin D and hearing loss...could there be a link?
Research published in the American Journal of Clinical Nutrition has revealed some interesting insights around vitamin D and hearing loss in the elderly.
Hearing loss is not simply about needing to increase the volume on the TV or asking others to ‘speak-up’ as we progress through the decades.
If hearing begins to deteriorate, it can leave us finding it hard to have conversations with family and friends. It may lead to problems with understanding a doctor’s advice or in hearing the doorbell ring. Not only this, loss of hearing, has been linked with increased risk of falls, depressive symptoms, and the development of dementia. In other words, we need to take it seriously.
Triggered by normal ageing, prior noise exposure, medical conditions as well as having a genetic influence, American researchers have now uncovered an association between people with low vitamin D status - defined as total vitamin D 20ng per ml or less, and low-frequency and speech-frequency hearing loss.
Their discovery came having poured over data, collected from 1,123 survey participants. Part of a nationally representative sample, those taking part answered health-related questions and underwent medical, dental and physiological measurements as well as laboratory tests over a five-year period.
Looking specifically at people 70 years plus, scientists found that in addition the link with vitamin D levels, those with lower bone density were also associated with greater odds of lower-frequency hearing loss.
These associations may seem baffling until you consider that of the 213 bones in our adult human skeleton, three called the 'malleus', 'incus' and 'stapes' sit, inside each of our inner ears (that's six in total), and four more form the part of our skull around each ear, two each side. That's 10 bones in total and damage to any may contribute to hearing loss.
How Vitamin D May Play A Role
The process of hearing is a fascinating phenomena and begins with our outer ears directing sound waves into the ‘external hearing canal’ where our eardrums pick them up, causing them to vibrate. These vibrations pass on, like a game of tag to the tiny malleus, incus and stapes and send their vibrations on to the snail shaped ‘cochlea’, sitting in our inner ears.
Filled with fluid and lined with extraordinarily fine hairs called cilia, these hairs, with the help of calcium ions, convert the vibrations into to nerve signals, which are transported to the brain where we perceived them as loud or quiet, speech, music or the phone ringing, and so on.
So where does bone health come into all of this? Well, bones may seem to be solid and unchanging but nothing could be further from the truth. They are a hive of activity, undergoing constant remodelling, with old cells being removed and new ones deposited.
This complex process needs among other things, a constant supply of nutrients including protein, vitamin K, phosphorus and of course calcium, which can only be absorbed from the foods we eat, if we have sufficient…vitamin D.
It is proposed that a lack of vitamin D and thus calcium can lead to micro-fractures in any of the 10 bones involved in hearing as well as lowering the presence of calcium ions in the cochlea, needed to convert sound vibrations into nerve signals.
It is a fascinating link and it is worth remembering that children and adults are advised by the Department of Health and Social Care in the UK, to take a daily supplement of vitamin D (for most of us, this is 10 micrograms), in winter and some, including people over 65, throughout the whole year.
Vitamin D and calcium have long been known to help protect our ‘big bones’, with adequate intakes helping to prevent rickets in children and osteomalacia (bone pain) and osteoporosis in adults. Now we have another potential reason to take both nutrients seriously; protecting our hearing as we age.