Long-time truck driver finds fast hearing improvements with the right hearing aid
December 2, 2010.
Age-related hearing loss may arise in part as a consequence of poor nutrition, specifically folate deficiency, a study of older men and women suggests. Patients with speech-frequency hearing loss had serum folate levels that were 32% lower than those of similar-age patients with normal hearing. Hearing loss in high frequencies was associated with 35% lower folate levels compared with patients who had normal high-frequency hearing. To a lesser and nonsignificant extent, age-related hearing loss also correlated with lower levels of vitamin B12, according to an article in the December issue of Otolaryngology – Head and Neck Surgery.
"These findings suggest that the low levels of these nutritional markers, particularly folate, may be significant for the development of hearing loss among these elderly subjects," Akeem Olawale Lasisi, MD, of the University of Ibadan in Nigeria, and co-authors wrote in the discussion of their findings.
"The fact that our subjects were ... apparently healthy elderly people suggests to us that the low serum folate and cobalamine (B12) might be the factor responsible for the hearing loss," they added.
Age-related hearing loss has been associated with a variety of environmental factors, including ambient noise, malnutrition, ototoxicity, and infection. At least two studies have shown an association between age-related hearing loss or dysfunction and low serum levels of cobalamine and folate. One of the studies found evidence of improved hearing following supplementation (J Neurol Sci 1994; 127: 11-28, Am J Clin Nutr 1999; 69: 564-571).
However, multiple studies have shown no link between hearing loss or dysfunction and nutrition, the authors noted.
Given the high prevalence of malnutrition in developing nations, Lasisi and colleagues examined the relationship between nutrition (specifically, folate and B12) and auditory function in older adults living in Nigeria. Investigators interviewed 126 apparently healthy men and women above 60 years of age.
Each participant underwent an extensive history and physical examination to rule out potential causes of hearing loss, such as medical conditions, prescription drugs, and regular exposure to high levels of environmental noise. Participants also had hearing assessments by pure tone audiometry (PTA). Blood samples were obtained during the physical exam.
The primary outcome was serum levels of folate and vitamin B12 in study participants with audiometric evidence of hearing loss in speech and high frequencies compared with levels in participants who had normal hearing. The prevalence of hearing loss in the range of speech frequency (0 to 30 dB) increased with age (P=0.03), and a trend toward association existed between older age and high-frequency hearing loss (P=0.09).
Participants with a normal hearing threshold (0 to 30 dB) had a mean serum folate level of 412.3 nmol/L compared with 279.1 nmol/L among participants with hearing loss. High-frequency hearing loss was associated with a mean folate level of 279.14 nmol/L compared with 426.3 nmol/L in men and women with normal PTA.
Serum cobalamine averaged 49.7 pmol/L in association with normal hearing threshold versus 42.6 pmol/L in participants with a higher hearing threshold. Normal high-frequency PTA was associated with a mean cobalamine level of 47.4 pmol/L, whereas study participants with high-frequency hearing loss had a mean value of 41.3 pmol/L.
In an unadjusted analysis, hearing loss in the high frequencies had a significant association with low serum folate (P=0.01) and cobalamine (P=0.02). After adjustment for age, serum folate remained significantly associated with high-frequency hearing loss (P=0.01) but cobalamine did not. Neither folate nor cobalamine had a significant association with speech-frequency hearing loss.
The study was not designed to address the question of whether supplementation of folate or vitamin B12 would reduce the risk of age-related hearing loss. The authors cited studies suggesting improvement in auditory function following treatment with B12 in combination with other agents and improvement in cognitive indices and peripheral and central nervous system symptoms after supplementation of B12, folate, or both nutrients.
"This may change our present belief about the irreversibility of age-related hearing impairment, thus improving the outcome of the disease and quality of life of the affected elderly people," the authors wrote in conclusion.
Source: Otolaryngology – Head and Neck Surgery, by Charles Bankhead, Staff Writer, MedPage Today
Lasisi AO, et al "Age-related hearing loss, vitamin B12 and folate in the elderly" Otolaryngol Head Neck Surg 2010; 143: 826-830.