The Effect of Folic Acid on Hearing in Older Adults

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The summary below is from the full report titled "Effects of Folic Acid Supplementation on Hearing in Older Adults. A Randomized, Controlled Trial." It is in the 2 January 2007 issue of Annals of Internal Medicine (volume 146, pages 1-9). The authors are J. Durga, P. Verhoef, L.J.C. Anteunis, E. Schouten, and F.J. Kok.

What is the problem and what is known about it so far?

Early research suggests that there may be a link between age-related hearing loss and blood levels of folic acid, a B vitamin. The link is not proven and has never really been tested in older adults.

Why did the researchers do this particular study?

To see whether taking folic acid pills slows age-related hearing loss in older adults.

Who was studied?

728 adults from the Netherlands who were 50 to 70 years old.

How was the study done?

The researchers performed a hearing test on each participant at the beginning of the study. They then assigned each participant at random to take folic acid or placebo pills every day for 3 years. They performed the hearing tests again at the end of the study and compared the hearing of the participants taking folic acid with the hearing of those taking placebo.

What did the researchers find?

Participants taking folic acid had less hearing loss than participants taking placebo.

What were the limitations of the study?

The difference in hearing loss between the 2 groups was small. People would have to take folic acid for many years to notice an effect at the hearing frequencies tested in the study. Also, the study was conducted in the Netherlands, where folic acid levels are about half of those in other countries, such as the United States. The findings might not apply to the United States and other countries where food is already fortified with folic acid.

What are the implications of the study?

Folic acid supplementation seemed to reduce hearing loss in older adults. The findings need to be confirmed over a longer time and in countries where food is fortified with folic acid before folic acid pills can be recommended as a way to reduce hearing loss in older people.