Iron deficiency anemia may be linked to hearing loss, new research has found.

Researchers studied 305,339 men and women ages 21 to 90, of whom 4,807 had hearing loss and 2,274 had iron deficiency anemia.

Hearing loss was more prevalent among women in the sample, and after adjusting for sex, the researchers found the risk for hearing loss was nearly two and a half times as high in those with anemia.

The risk for sensorineural hearing loss, the type linked to problems in the nerves of the inner ear, was 82 percent higher in those deficient in iron. There was an insignificant increase in risk for those with conductive hearing loss, caused by a problem in the ear canal, eardrum or bones of the middle ear. The study is in JAMA Otolaryngology — Head & Neck Surgery. Many cases of hearing loss have no known cause.

Although the reason for the association remains unknown, animal studies suggest that iron deficiency may reduce blood flow to the inner ear, affecting the cochlear ganglion, the group of nerve cells that transmit sound to the brain.

“Our study does not say that iron deficiency causes hearing loss, but only that there is a link between the two,” said the lead author, Kathleen M. Schieffer, a doctoral candidate at Pennsylvania State University. “I would not recommend that anyone take iron supplements prophylactically without consulting a physician.”