The combination of nutrients taken one hour before noise exposure and continued as a once-daily treatment for five days, was very effective at preventing permanent noise-induced hearing loss. The animals had prolonged exposure to sounds as loud as a jet engine at take-off at close range.
"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," says Josef M. Miller, Ph.D., the senior author of the study. Miller is a professor in the Department of Otolaryngology at the University of Michigan Medical School.
In the University of Michigan 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 study’s lead author and a research investigator at the University of Michigan 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.
MEDICA.de; Source: University of Michigan Health System