Written by Marcia J. Egles, MD. 3 year supplementation with folic acid slowed the progression of age-related hearing loss in older adults.
As published in Annals of Internal Medicine, folic acid supplementation has been reported to slow the decline of age-associated hearing loss. The study was performed in the Netherlands, a country without folic acid fortification of food. It demonstrated that daily oral folic acid supplements (800 µg), over a three year trial, slowed the decline of age-associated hearing loss in older adults.
Age-related hearing loss is one of the most common chronic conditions of older people. Some prior studies have found an association between higher blood folate levels and better hearing function(1,2,3,4) and have suggested the need for a controlled, clinical trial. This new study, a controlled trial of fair size and duration, addressed that need.
The study compared the hearing function of those who received folate to a control group that received placebo capsules. Each participant’s hearing was tested at the start of the study. Participants were then randomly assigned to take 800 µg of folic acid daily or placebo pills for three years. Participants had their hearing tested again at the end of the study.
The study was double-blinded, which means that neither the participants nor the researchers knew who was receiving the placebo vs. the folic acid. The participants included 738 men and postmenopausal women 50-70 years of age who were recruited from blood bank registries. People with medical problems that might interfere with folate metabolism were excluded, as well as those with hearing loss that was likely not age-related. Participants were not allowed to take additional B vitamin supplements.
Blood levels of folate, vitamin B12, and homocysteine were measured at the start and at the end of the study. Participants also answered food frequency questionnaires at the start of the study to determine folate intakes. The blood levels of approximately 9% of the participants were folate-deficient at the start of the study, and the average dietary folate intake was only 195 µg, which is less than the recommended daily allowance of 300 µg per day.
Researchers found that those taking folic acid had less hearing loss than those taking placebo. Both the folic acid group and the placebo group had progression of hearing loss over the three years, but the folic acid group had 0.7 decibels less loss on average than the control group. This would be a small but just noticeable difference in hearing ability. This difference was found only in the low frequency hearing range. High frequency hearing loss was not found to be affected. (The study noted that high frequency hearing loss begins at younger ages and a trial with younger subjects would be needed to determine if there might be a benefit of folic acid for high frequency loss.) No participants had improvement of existing hearing loss. Participants who entered the study with low folate status had a stronger response to folic acid treatment.
Source: Durga, Jane, Petra Verhoef, Lucien JC Anteunis, Evert Schouten, and Frans J. Kok. “Effects of Folic Acid Supplementation on Hearing in Older Adults A Randomized, Controlled Trial Folic Acid and Hearing.” Annals of internal medicine 146, no. 1 (2007): 1-9.
© 2007 American College of Physicians
Posted August 5, 2008.
References:
- Houston DK, Johnson MA, Nozza RJ, Gunter EW, Shea KJ, Cutler GM, et al. Age-related hearing loss, vitamin B-12, and folate in elderly women. Am J Clin Nutr. 1999;69:564-71. [PMID: 10075346]
- Berner B, Odum L, Parving A. Age-related hearing impairment and B vitamin status. Acta Otolaryngol. 2000;120:633-7. [PMID: 11039875]
- Cadoni G, Agostino S, Scipione S, Galli J. Low serum folate levels: a risk factor for sudden sensorineural hearing loss? Acta Otolaryngol. 2004;124:608-11. [PMID: 15267180]
- Gok U, Halifeoglu I, Canatan H, Yildiz M, Gursu MF, Gur B. Comparative analysis of serum homocysteine, folic acid and Vitamin B12 levels in patients with noise-induced hearing loss. Auris Nasus Larynx. 2004;31:19-22. [PMID: 15041049]
