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," explains Colleen G. Le Prell, Ph.D., the studys lead author and a research investigator at the U-M Kresge Hearing Research Institute. According to the researchers, pre-treatment presumably reduced reactive elements called 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 over-stimulation. The post-noise nutrient doses apparently "scavenged" free radicals that continue to form long-after after this noise exposure ends.

In the past 10 years, scientists have learned that noise-induced hearing loss occurs in part because cell mitochondria in the ear churn out damaging free radicals in response to loud sounds. "Free radical formation bursts initially, then peaks again during the days after exposure," explains Le Prell.

The antioxidant vitamins and magnesium used in the study are widely used dietary supplements, not new drugs, and therefore they dont require the extensive safety tests required for new drug entities prior to use in clinical trials. The doses t
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Contact: Kara Gavin
kegavin@umich.edu
734-764-2220
University of Michigan Health System
28-Mar-2007