From Bench to Bedside: Can You Hear Me Now?
U-M scientists research effectiveness of nutritional supplements for preventing hearing loss
About 9 million Americans suffer from some degree of noise-induced hearing loss. In children, hearing impairment can affect their education. In adults, it compromises job opportunities, productivity and satisfaction. And, in the elderly, it can lead to isolation.
University of Michigan researcher Josef M. Miller, Ph.D., a professor in the Department of Otolaryngology at the Medical School, and Colleen Le Prell, Ph.D., a research investigator formerly at the U-M Kresge Hearing Research Institute, are working to develop a way to prevent noise-induced hearing loss. They have led animal studies that show a hearing-protection tablet, or nutritional supplement, can prevent permanent noise-induced hearing loss.
In the past 10 years, scientists have learned that noise-induced hearing loss occurs in part because cell mitochondria in the ear produce damaging free radicals in response to loud sounds.
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 very effective at preventing permanent noise-induced hearing loss in animal studies.
According to the U-M researchers, pre-treatment presumably reduced the excessive free radicals that form during and after noise exposure and noise-induced constriction of blood flow to the inner ear. The nutrients may also reduce the damage to auditory neurons that can occur due to over-stimulation.
Free radical formation continues to occur as much as three days after exposure. The study suggested a “morning after” treatment that might minimize hearing damage for soldiers, musicians, pilots, construction workers and others—even if they don’t take it until after they experience dangerous noise levels.
Trials Under Way
Michigan researchers were recently awarded a $2.7 million grant from the National Institutes of Health to test the effectiveness of the nutrients, a formulation called Auraquell™, in preventing noise-induced hearing loss in adults.
The antioxidant vitamins and magnesium used in the studies are widely used dietary supplements, not new drugs. Therefore, they don’t require the extensive safety tests required for new drugs prior to use in clinical trials.
The first two trials will assess Auraquell’s potential for reducing temporary hearing loss in two groups: Swedish military officers undergoing urban warfare training in which they fire an automatic weapon and college students at the University of Florida—where LePrell now works—listening to MP3 players.
The second two trials will determine if Auraquell can prevent permanent hearing loss among military personnel working at an air base and workers in a stamping factory.
The results of the trials will be evaluated at U-M. Miller, along with two neurobiologists, have formed a start-up company called OtoMedicine Inc. that holds the license for developing products that may come from the research.
“Ultimately, we envision soldiers will have a nutritional bar with meals to give them adequate daily protection,” Miller says. Similar bars with other formulations are already given to soldiers to help them withstand hot weather and other war zone conditions.
“People would also likely benefit by consuming a pill or nutritional bar before going to work in noisy environments, or attending noisy events like NASCAR races or rock concerts, or even using an iPod or other music player,” Le Prell says.
The U-M study also lends strength to research efforts happening in many research centers to learn how these nutrients might be used to treat other illnesses.
“Similar combinations have been very effective in preventing macular degeneration, and many of these agents have been used with Alzheimer’s and Parkinson’s diseases, stroke-like ischemia, and other conditions involving neural degeneration,” Le Prell says.
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