WEDNESDAY,Jan. 3 (HealthDay News) -- Age-related hearing loss, a common problemamong the elderly, might be related to inadequate levels of folic acid,European researchers report.
The researchers found that peoplewho took a folic acid supplement had less decline in hearinglow-frequency sounds over time, compared with people who didn't takethe supplement.
Results of the study, led by Jane Durga, of theCognitive Sciences Group, Nutrition & Health Department at theNestle Research Center in Lausanne, Switzerland, are published in theJan. 2 issue of the Annals of Internal Medicine.
Theresearchers randomly assigned 728 older Dutch men and women, who showedsigns of age-related hearing loss and low folate levels, to receiveeither 800 grams of a folic acid supplement or a placebo daily forthree years.
Durga's team chose to conduct the study in theNetherlands because, unlike the United States, the Netherlands does notfortify its food with folic acid, a B vitamin also known as folate.Folate levels in study participants were about half those found inAmericans. In the United States, many foods contain supplemental folicacid because of its benefits in protecting against birth defects.
Atthe end of the trial, the researchers found that the ability to hearlow-frequency sound did not decrease significantly among those takingfolic acid supplements. However, there was no slowing in the decline inhearing high frequencies in either group.
The thresholds of thelow frequencies increased by 1.0 decibel in the folic acid group and by1.7 decibels in the placebo group, the researchers said.
"Folicacid supplementation slowed the decline in hearing of the speechfrequencies associated with aging in a population from a countrywithout folic acid fortification of food," the researchers wrote. "Theeffect requires confirmation, especially in populations from countrieswith folic acid fortification programs."
But Robert W. Sweetow,director of audiology at the University of California, San Francisco,Medical Center, called the results "clinically insignificant."
"Ithink that their conclusion that folic acid is actually slowing downthe progression of age-related hearing loss is a stretch," Sweetowsaid. "I would hate to say to patients, 'You take folic acid and theprogression of your hearing loss is going to slow down.'"
Another expert questioned the significance of the finding.
"Theeffect is on low frequency hearing, but most older folks have a problemwith high frequency hearing," said Dr. Hinrich Staecker, an associateprofessor in the department of otolaryngology-head & neck surgeryat the University of Kansas Medical Center.
Staecker also notedthat the study authors didn't look at the ability of the participantsto hear speech clearly. "It's easier to make stuff louder, but it's noteasy to make stuff clearer," he said.
Dr. Peter M. Rabinowitz,an associate professor of medicine at the Yale University School ofMedicine, said, "The investigators' finding that low-frequency, but nothigh frequency, hearing loss was reduced in the folate supplementationgroup is somewhat surprising, since age-related hearing loss usuallyaffects the higher frequencies of hearing first and to a greaterdegree."
Clearly, much is not known about nutrition and hearing,Rabinowitz said. For example, other studies have suggested that geneticdifferences in the metabolism of folate may affect how someone respondsto supplementation, including the effect of folate on hearing loss, hesaid.
"While neither this study nor the current state of medicalknowledge provide adequate evidence for recommending particularsupplements to prevent hearing loss, this study provides additionalevidence of the importance of adequate nutrition in older adults, aswell as the potential for future discoveries of how to slow the agingprocess of the hearing system," Rabinowitz said.
More information
The U.S. Food and Drug Administration can tell you more about age-related hearing loss.
