Study: Vitamins, Minerals May Prevent Hearing Loss

ANN ARBOR, Mich.—A University of Michigan study on guinea pigs suggests that a combination of high doses of vitamins A, C and E, and magnesium, taken one hour before noise exposure and continued as a once-daily treatment for five days was effective at preventing permanent noise-induced hearing loss.

Researchers say the findings may help prevent hearing loss in war zones, concert halls and workplaces. Clinical trials of a hearing-protection tablet or snack bar for humans could begin soon and, if successful, such a product could be available in as little as two years, said Josef M. Miller, PhD, senior author of the study, which is published online in the journal Free Radical Biology and Medicine.

Miller is a professor in the Department of Otolaryngology at the U-M Medical School, and former director of the U-M Health System’s Kresge Hearing Research Institute, where the study was performed.

Convinced by emerging evidence that nutrients can effectively block inner-ear damage caused by excessive free-radical activity, Miller has launched a U-M start-up company, OtoMedicine, that is developing the vitamin-and-magnesium formulation.

“These agents have been used for many years, but not for hearing loss. We know they’re safe, so that opens the door to push ahead with clinical trials with confidence we’re not going to do any harm,” he said.

The formulation used for the study were based on results of earlier animal studies showing that single antioxidant vitamins were somewhat effective in preventing hearing loss, and on studies of Israeli soldiers given magnesium many days prior to exposure, who gained relatively small protective effects.

In the U-M study, noise-induced hearing loss was measured in four groups of guinea pigs treated with the antioxidant vitamins A, C and E, magnesium alone, an ACE-magnesium combination, or a placebo. The treatments began one hour before a five-hour exposure to 120 decibel (dB) sound pressure level noise, and continued once daily for five days.

The group given the combined treatments of vitamins A, C and E and magnesium showed significantly less noise-induced hearing loss than all of the other groups.

“Vitamins A, C and E and magnesium worked in synergy to prevent cell damage,” explained Colleen G. Le Prell, PhD, the study’s lead author and a research investigator at the U-M Kresge Hearing Research Institute. According to the researchers, pre-treatment presumably reduced free radicals that form during and after noise exposure and noise-induced constriction of blood flow to the inner ear, and may have also reduced neural excitotoxicity, or the damage to auditory neurons that can occur due to overstimulation. The post-noise nutrient doses apparently “scavenged” free radicals that continue to form long-after after this noise exposure ends.