Originally published December 5 2009
Hearing loss is not an inevitable part of aging
by S. L. Baker, features writer
(NaturalNews) NaturalNews has already reported how a long-accepted "fact" about aging -- that our brains shrink -- has turned out to be bogus science. (http://www.naturalnews.com/027212_brains_agi...). Now comes research that strongly suggests another medical "fact" about getting older is just plain wrong. New evidence indicates that a physical problem considered to be virtually inevitable as people age, hearing loss, could be preventable by eating an antioxidant rich diet or by taking antioxidant supplements.
The most common sensory disorder among elders, hearing loss affects more than 40% of people in the US over age 65, according to data from the National Health Survey. And hearing loss is expected to be a problem for at least 28 million older Americans by 2030. Losing hearing acuity in later years involves the death of nerves, hair and membrane cells inside the inner ear. Because the hair and nerve cells are not thought to be capable of regeneration, their death causes permanent hearing loss. But is it just living into middle age and beyond that causes these changes? Findings recently published online in the Proceedings of the National Academy of Sciences indicate the answer is "no".
Antioxidants protect against hearing loss
University of Florida (UF) researchers, along with scientists from the University of Wisconsin and three other institutions, have identified a protein that appears to be the key that directs processes causing oxidative damage to cells. The result of this damage is hearing loss. These findings suggest protecting against oxidative damage with antioxidant therapies or by regularly eating antioxidant rich foods could potentially prevent or even treat hearing loss in older adults.
A popular theory of aging revolves around the concept that oxidative damage from free radicals harms the mitochondria, the energy center of cells. When the damage continues over months and years, the mitochondria are thrown into havoc and release proteins that cause cells to die. This leads to a host of physical effects associated with aging -- including hearing loss.
"Within the mitochondria these proteins cause life, but when they're out they're deadly," Professor Christiaan Leeuwenburgh, Ph.D., chief of the biology of aging division at UF's College of Medicine and a member of the Institute on Aging, said in a statement to the media.
A particular protein dubbed Bak is induced by oxidative stress and levels of this protein increase when people age. Bak is known to play a specific role in weakening the mitochondrial membrane, making it leaky and allowing harmful proteins to move into the rest of the cell. So, to find out if Bak is involved in age-related hearing loss, the scientists studied middle-aged mice bred to be deficient in Bak. They found the animals had hearing levels comparable to far younger mice.
Then the researchers exposed inner ear cells of the Bak lacking mice to a chemical that caused oxidative stress. The result? There was only a minor loss of cells related to hearing. So the research team concluded it must be Bak, produced in response to oxidative stress, that pushes the death of cells in the auditory portion of the inner ear. And because older people faced with oxidative stress (from chemicals, drugs, air pollution, processed foods, etc.) over the years have more and more Bak in their bodies, it is easy to see the connection to hearing loss.
In addition, the scientists discovered that the onset of age-related hearing loss was significantly delayed in animals with excess amounts of an enzyme that scavenge free radicals, as well as in animals that were fed antioxidants. "This paper clearly shows us that oxidative stress causes hearing loss," said Jinze Xu, a UF postdoctoral fellow, in the media statement. Bottom line: if oxidative stress triggers damage and death of hearing-related cells, boosting the defenses of the mitochondria with antioxidants should prevent or reduce this damage.
Editor's note: NaturalNews is opposed to the use of animals in medical experiments that expose them to harm. We present these findings in protest of the way in which they were acquired.
For more information:
http://news.ufl.edu/2009/11/09/hearing-loss/
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