A new study has found that folic acid may help maintain auditory health for the loss of hearing that gradually occurs in most individuals as they grow older.

Nutrition for Optimal Wellness | Greg Arnold, DC, CSCS | Defined by the Deafness Research Foundations as “the loss of hearing that gradually occurs in most individuals as they grow older”, presbycusis is estimated to affect up to 35% of adults between the ages of 65 and 75 years and 50% of people 75 and older(1). Presbycusis is the most common type of hearing loss in the United States (2).

There are several causes of presbycusis, but the most common cause is changes in how the bones of the inner ear transmit sound as well as changes in the hair cells of the inner ear, making them less sensitive to sound waves Presbycusis can also be caused by changes in the blood supply to the ear due to heart disease, high blood pressure, diabetes, or other circulatory problems (1).

While hearing aids are the most common treatment for presbycusis, a new study (3) has found that folic acid may help maintain auditory health. Researchers looked at 2,956 patients older than 50 years participating in The Blue Mountains Hearing Study (4). They were tested for presbycusis and their blood levels of the inflammatory protein homocysteine, as well as vitamins B-12 and folic acid, were measured. The researchers were looking at homocysteine due to aforementioned causes of presbycusis via chronic disease of which homocysteine frequently plays a significant role (5). They defined elevated homocysteine levels as greater than 20 micromoles/Liter.

The researchers found that having elevated homocysteine levels increased the risk of presbycusis by 64%. They then found that having low blood levels of folic acid (less than 11 nanomoles/Liter) increased the risk of presbycusis by 37%. No significance was found between vitamin B12 blood levels of presbycusis. When suggesting how homocysteine can precipitate hearing loss, the researchers pointed to earlier research in mice showing high homocysteine to affect blood circulation in a structure in the ear called the cochlea (6).

For the researchers, “[Blood levels] of [homocysteine] and folate were associated with age-related hearing loss.”

Reference:

1. “Presbycusis” - http://www.drf.org/Presbycusis
2. Wallhagen MI. SENSORY IMPAIRMENT IN OLDER ADULTS: PART 1: HEARING LOSS: Hearing impairment is a significant, often debilitating, problem for many older adults, but assessment and intervention by nurses can help. 2006; 106(10): 40–48
3. Gopinath B. Serum Homocysteine a nd Folate Concentrations Are A ssociated w ith P revalent Age-RelatedHearingLoss. Jou Nutr. First published ahead of print June 23, 2010 as doi: 10.3945/jn.110.122010.
4. Berner B, Odum L , Parving A. Age-related hearing impairment and B vitamin status. Acta Otolaryngol. 2000;120:633–7
5. Clarke R. Homocysteine and Risk of Ischemic Heart Disease and Stroke, A Meta-analysis. JAMA. 2002;288:2015-2022
6. Kundu S, Tyagi N, Sen U, Tyagi SC. Matrix imbalance by inducing express ion of metalloproteinase and oxidative stress in cochlea of hyperho mocysteinemic mice. Mol Cell Biochem. 2009;3 32:215–24

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