Life Extension Magazine®

Man having ear examined for hearing loss from homocysteine levels

Homocysteine and Hearing Loss

Recent studies indicate that hearing loss involves damage to brain cells that support hearing—and that elevated homocysteine contributes to this loss. Low-cost B vitamins combat the dangers of high homocysteine and may help prevent age-related hearing loss.

Scientifically reviewed by: Dr. Heidi Yanoti, DC, in October 2024. Written by: Clyde Simmons.

Hearing loss is considered to be a normal part of aging, but recent studies indicate otherwise.

Research published over the past two years has identified an underlying cause of hearing loss not routinely considered by physicians.

These findings reveal that age-related hearing loss involves damage not just to the cells in the ear itself, but to nerve cells that support hearing.¹ This suggests that proven nervous system-protective strategies could be beneficial for hearing as well.

Most importantly, it reveals that elevated homocysteine—long associated with cardiovascular and neurological conditions—also contributes to hearing loss.²

Fortunately, research shows that supplementing with folate helps lower homocysteine while also protecting against the damage that it causes.²

This represents a novel approach to potentially mitigating hearing loss.

What you need to know

Homocysteine is a harmful form of an amino acid that has been shown to increase the risk of cardiovascular and neurological conditions. Surprisingly, new research shows that it also has a connection with hearing loss. A recent large-scale clinical trial of older adults showed that when homocysteine was lowered using folate, there was significantly less hearing loss compared with placebo after three years.

An Unexpected Cause of Hearing Loss

Sensorineural hearing loss, the kind associated with aging, reduces the ability to hear faint sounds while also making louder noises sound muffled.

The discovery that this type of hearing loss is caused by damage to nerve cells as well as to sound-sensing cells in the ear led scientists to look for factors common to both age-related hearing loss and brain degeneration.¹

An article published in 2017 reported on the growing epidemiological evidence of a strong association between elevated homocysteine and hearing loss.²

The 2017 study showed:

High total plasma homocysteine is strongly associated with age-related hearing loss.
Rare genetic diseases that cause high homocysteine levels are also strongly associated with sensorineural hearing loss.
Animal studies demonstrating that high homocysteine levels—as well as deficiencies in vitamins required to clear homocysteine—produce the type of hearing loss seen in older people.

These findings bring together a clear relationship between hearing loss and homocysteine. They also highlight the role for nutritional supplementation as a potential means of preventing age-related deafness.

Hearing Loss in Older Adults: A Combination of Ear and Brain Injury

Not all forms of hearing loss are the same. The two most common forms of hearing loss are:¹⁵

• Conductive – in which sound cannot reach the inner ear, or cochlea, because of defects in the eardrum or the three tiny bones that connect it with the cochlea. Common causes are physical trauma or infection.

• Sensorineural – in which sound reaches the cochlea without trouble, but because of damage to the cochlea itself, or to the auditory nerve, the sound cannot be properly converted into nerve impulses that reach the brain.

Sensorineural hearing loss is the most common form of age-related hearing loss.^16,17 It typically involves nerve damage – either to the minute hair cells in the cochlea that convert sound waves into nerve impulses, or to the nerve cells that transmit those impulses to the brain.^1,17

Anatomy of Hearing

Sound waves in the air enter the outer ear and pass through the ear canal to vibrate the ear drum. The drum then vibrates the three tiny bones (ossicles) in the middle ear space, which in turn press on a tiny window in the cochlea. The fluid-filled cochlea, in turn, transmits those now-amplified vibrations to move minute projections on sound-sensing hair cells, which convert vibrations to nerve impulses. The collective bundle of nerve cells that leaves the cochlea form the auditory nerve (cochlear and vestibular nerve), which transmits those signals to the brain, where they are interpreted as sounds.

While we once assumed that sensorineural hearing loss involved damage to those hair cells, recent studies show that up to 50% of the nerve connections between hair cells and the auditory nerve may be lost before detectable damage to hair cells occurs. The implication is that this common form of hearing loss is as much a nervous system condition as it is an ear condition.¹

This means that anything that damages nerve cells will damage the connections between hair cells and the auditory centers of the brain, leading to sensorineural hearing loss. These factors include oxidative stress and resulting inflammatory changes, as well as mitochondrial dysfunction and, eventually, cell death.¹⁸

These considerations are making scientists take a second look at the role played by homocysteine in hearing loss.

High homocysteine levels are known to be associated with blood-vessel and nervous-system cell damage, and to contribute to stroke, Alzheimer’s, and Parkinson’s diseases.^19-25 Lowering homocysteine can help prevent those conditions.

It now makes perfect sense to use B vitamins to combat hearing loss as well as other forms of chronic, age-related brain disorders.

The Homocysteine/Folate Connection

Another recent article showed that a dietary deficiency in folic acid, a B vitamin necessary for clearing homocysteine from the blood, is associated with hearing loss.³ This is one of the key connections between homocysteine and hearing loss.

This study showed that after eight months of feeding healthy mice a diet deficient in folic acid, the animals started showing signs of hearing loss. Closer examination showed that their cochleae (the part of the ear where sound is converted to nerve impulses) was damaged and there was a loss of outer hair cells.³

Human studies have shown similar connections. When researchers evaluated people over 60 years old, they found that those with normal hearing had normal folate levels, while those with hearing loss had low folate levels.⁴

In a study involving nearly 3,000 people age 50 or older, those with elevated total homocysteine levels were 64% more likely to have hearing loss compared with those having lower homocysteine levels.⁵ Again, most of that elevated risk was related to low plasma folate levels.

Other studies have shown similar hearing problems associated with low levels of vitamin B12, which is also required for lowering homocysteine.⁶

Facts About Hearing Loss in Older Adults¹⁴

• Hearing loss is the third most common chronic physical condition among American adults. It is twice as prevalent as diabetes or cancer.

• Nearly half of people over age 60 have hearing loss, amounting to 46 million Americans in 2014 and predicted to grow to 82 million by 2040.

• People with hearing loss do worse socially and economically, are more likely to be unemployed, and have higher healthcare costs than those with normal hearing.

Mysterious Epidemic Causes Hearing Loss

The first indication that restoring folate levels could impact hearing came nearly a quarter-century ago. At the time, a mysterious epidemic swept through Cuba, leaving more than 50,000 people suffering from a range of maladies related to poor nerve function. The most prominent included sensorineural hearing loss and deafness.⁷

No one ever found a cause. But when the government began treating victims with folate and other B vitamins, most patients had near-miraculous improvement, leaving less than one-tenth of one percent with permanent deficits.

Investigators concluded that micronutrient deficiencies—including thiamine, folate, and B12—were the root of the problem.⁷

Since that dramatic event, evidence has continued to reveal that folate supplementation can prevent, slow, and possibly even reverse age-related hearing loss.⁸

Folate Reverses Hearing Loss

A mouse study showed that high homocysteine levels led to significant leakage from blood vessels in brain areas associated with hearing, and surrounding tissues suffered severely from homocysteine-induced chemical stress.⁹ But when those mice were supplemented with folate for four weeks, the tissue levels of homocysteine plummeted, and the leaky blood vessels completely healed.

This suggested that reducing homocysteine levels with folate could potentially reverse ongoing hearing loss.⁹

A human study confirmed the hearing-related benefits.

More than 700 older adults with high homocysteine (but no hearing problems) were given 800 mcg of folate per day or placebo for three years.¹⁰ While all subjects experienced mild hearing losses during the three-year period, the placebo group experienced a greater loss of hearing in low frequencies than the folate-supplemented group.

This helps demonstrate that regular folate supplementation is capable of slowing age-related hearing loss.¹⁰

Life Extension Recommendations on Homocysteine

Homocysteine levels should be part of a yearly battery of blood tests to ensure a healthy, long life. Life Extension® advises that one should target their homocysteine levels below 12 µmol/L with ideal numbers being <8 µmol/L.

Conventional reference ranges do not flag a homocysteine problem until blood levels reach 15 µmol/L. Published data reveal those with homocysteine blood levels between 10-15 µmol/L suffer greater risks.^11-13

Individuals with elevated homocysteine levels should begin supplementation with key B vitamins, especially higher doses of the activated form of folate (5-MTHF), and retest homocysteine blood levels after three months.

Summary

Rising levels of homocysteine are now closely associated with both brain-cell injury and hearing loss. Strategies aimed at lowering homocysteine levels, such as folate supplementation, convincingly slow hearing loss.

Supplementing with folate offers a unique strategy for combatting the dangers of elevated homocysteine—and represents a novel solution for preventing age-related hearing loss.

An issue for older individuals is that they lack the internal enzymes to convert folate from food and folic acid supplements to bioactive 5-methyltetrahydrofolate (5-MTHF).

For a long time, the only way of gaining access to this metabolically active folate (5-MTHF) was through an expensive prescription drug called Cerofolin® that cost over $150 a month.

Fortunately, the 5-MTHF patents expired several years ago. This enables consumers to gain access to optimized folate supplements that provide 1,000 to 5,000 mcg of 5-MTHF, along with other B-vitamins (methylcobalamin B12, pyridoxal-5-phosphate B6 and vitamin B2), that work together and individually to reduce homocysteine via two detoxification pathways in the body.

If you have any questions on the scientific content of this article, please call a Life Extension® Wellness Specialist at 1-866-864-3027.

References

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