Folic acid may slow age-related hearing loss

NEW YORK (Reuters Health) - Folic acid supplementation appears to slow the decline in hearing that commonly occurs with age, at least in people with high levels of the amino acid homocysteine, according to a study conducted in the Netherlands.

Folic acid, also called folate, is a B vitamin, which the body uses to make new cells. Previous reports have linked low folate levels with poor hearing, but it was unclear if administration of the vitamin could slow age-related hearing loss, the study team explains in a report in the Archives of Internal Medicine for January 2.

To investigate, Dr. Jane Durga, from the Nestle Research Center in Lausanne, Switzerland, and colleagues assessed changes in hearing among 728 subjects, between 50 and 70 years of age, who were randomized to receive folate (800 micrograms) or inactive placebo daily for 3 years.

Because there is evidence that folate may improve hearing by lowering plasma homocysteine levels, the researchers excluded subjects who had low homocysteine levels at the start of the study. None of the subjects had any pathologic ear conditions unrelated to aging.

At 3 years, the threshold for low frequency hearing increased by 1.0 dB in the folate group, significantly less than the increase noted in the control group.

By contrast, high frequency auditory acuity worsened by a similar extent in each group, the researchers found.

Whether the current findings are applicable to subjects in the US is unclear, the authors note. At the time of the study, folate fortification of foods was prohibited in the Netherlands and, as a result, the subjects had baseline folate levels that were about half of those typically seen in the US population.

Dr. Robert A. Dobie, from the University of California at Davis, suggests in a written commentary that if the improvement in hearing is confirmed in other investigations, and if baseline hearing tests predict who will benefit, hearing tests in middle age to select candidates for treatment “might prove to be cost-effective in areas where folate deficiency is prevalent.”

SOURCE: Archives of Internal Medicine January 2, 2007.