| |
As printed in Hearing Health, volume 21:1,
Spring 2005
By Jenifer M. Woo, Au.D., and Sandra L. McFadden, Ph.D.
Nearly 30 million Americans are exposed to damaging levels of noise every day and, as a result, more than 30 percent of these individuals experience noise-induced hearing loss, making it the most common acquired type of hearing loss in the United States and other industrialized nations. This plague of hearing loss is largely preventable with proper use of ear protection like earplugs and earmuffs, yet ear protection is often misused or not used at all. Some people may never get into the habit of using hearing protection but perhaps there is something else they can do to lessen the effects of toxic noise on their hearing. And it’s something they may already have as a habit — taking daily vitamin supplements.
Our recent research indicates that vitamin C could be critical in protecting against the effects of toxic noise. Our findings are that of one animal study and one noise exposure condition of limited duration. Therefore further research and clinical trials must be completed before we can definitively declare vitamin C’s benefits for human hearing. Nonetheless, the results are promising and vitamin C has well-documented benefits for many other aspects of our health.
The Noise-Nutrition Connection
In a healthy person, the body maintains a balance of free radicals (also called reactive oxygen species) and antioxidants in the arteries, skin, hair — in all parts of the body, including the inner ears. Free radicals are naturally produced by cells as byproducts of normal metabolism and by the immune system to destroy viruses and bacteria. Antioxidants are naturally produced by the body to keep free radicals from becoming harmful to healthy cells. As long as free radicals and antioxidants maintain an appropriate balance, no damage occurs.
However, a traumatic event, such as overexposure to loud noise, can generate high levels of free radicals in the inner ear that can overwhelm antioxidant defenses. As a result, structural and genetic damage occurs to cells and organelles in the inner ear.
If an excess of free radicals can cause damage, then an increase in antioxidant defenses may prevent damage, an approach to preventing noise-induced hearing loss that researchers are currently exploring. Over the past 10 years, researchers have found several different antioxidants that have been helpful in preventing noise damage to experimental animals. Such antioxidants include glutathione and N-acetylcysteine. However, the methods used to administer these antioxidants have been invasive and complicated, thus limiting their potential benefit for protecting individuals from unplanned exposure to noise.
Hearing health researchers are still looking for a practical way of combating the free radicals that cause hearing loss and it may very well be right under our noses. Vitamin C is one of the most abundant and readily available antioxidants in the human diet and has been proven effective in combating many disease processes including colon cancer, breast cancer, asthma symptoms, cataracts and glaucoma, heart disease and now hearing loss. Vitamin C is a water-soluble molecule which enables it to easily cross cell membranes to neutralize potentially damaging free radicals inside the cell.
Vitamin C Beneficial in an Animal Study
In our study, albino guinea pigs were fed a custom pellet diet that varied only in the content of vitamin C. The guinea pigs were divided into three diet groups: vitamin-C deficient, normal levels of C and vitamin-C supplemented. A hearing test conducted before and after diet consumption showed no significant difference in hearing for any diet group. Then each guinea pig underwent one noise exposure of equal duration and intensity that mimicked industrial noise. There was a predicted significant loss of hearing, which varied among diet groups, following the noise exposure. The deficient and normal diet groups developed mild to moderate hearing loss whereas the vitamin-C-supplemented group developed only slight hearing loss.
Protection Any Time
Wouldn’t it be great if there was a pill you could take before stepping into a night club or one that soldiers could take before entering the battlefield to prevent post-traumatic symptoms like hearing loss or ringing in the ears? Whereas many people can anticipate their exposure to noise, particularly if it comes from the workplace or a regular recreational activity, exposure to noise can also be sudden and unpredictable. Perhaps taking a daily supplement of vitamin C with the mindset that, “Just in case I encounter a loud noise today, I’ll have ready antioxidant protection,” is not a bad idea. When you think how vitamin C can help your body fight cancer, heart disease and cataracts, its potential to reduce noise-induced hearing loss would be a bonus.
Jenifer M. Woo, Au.D., is lead audiologist at Grady Memorial Hospital in Atlanta, GA. A graduate of the University at Buffalo, Dr. Woo completed this study as part of her doctor of audiology degree requirement. Vice president of the National Association of Future Doctors of Audiology in 2004, Dr. Woo is an active participant in the professional community.
Sandra L. McFadden, Ph.D., is a research scientist at the Center for Hearing and Deafness and a research associate professor in the Dept. of Communicative Disorders and Sciences at the University at Buffalo. Dr. McFadden's research is aimed at understanding and preventing acquired hearing loss, particularly age-related hearing loss, or presbycusis.
Related Articles:
It's having your hearing checked regularly.
It's having a strong heart.
It's good nutrition.
It's protecting your ears from noise.
|
|
