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Lee Swanson Research Update
Antioxidants May Slash Risk of Hearing Loss
August 2011
Increased intakes of antioxidant vitamins A and E may significantly reduce the risk of hearing loss, according to a new study from Australia.
People with the highest average intakes of vitamin A had a 47% reduced risk of moderate or greater hearing loss, compared to people with the lowest average intakes, scientists from the University of Sydney reported in The Journal of Nutrition, Health & Aging. In addition, increasing dietary vitamin E intakes were linked with a 14% reduction in hearing loss.
The researchers, led by Professor Paul Mitchell, note that reactive oxygen species may damage the inner portion of the ear associated with hearing, therefore leading to a hypothesis that antioxidants may counter this damage and reduce age-related hearing loss.
"Our cross-sectional findings supported this hypothesis; specifically, higher dietary vitamin E intakes were associated with a reduced likelihood of hearing loss," they wrote.
Hearing loss is the most common sensory disorder in the United States, affecting more than 36 million people.
The research adds to other observations from Prof. Mitchell’s lab, with a previous report supporting a role for omega-3 fatty acids to reduce hearing loss (American Journal of Clinical Nutrition 92:416-421).
For the new study, the Australian scientists analyzed data from 2,956 people participating in the Blue Mountains Hearing Study. Dietary intakes of a range of antioxidants, including alpha- and beta-carotene, beta-cryptoxanthin, lutein, zeaxanthin, lycopene, vitamins A, C and E, and iron and zinc, were assessed using a food frequency questionnaire.
Results showed that, over five years of study, both vitamin A and E were associated with reductions in the risk of hearing loss, but no significant associations were observed for dietary intake of other antioxidants.
"[The result for vitamin A] is biologically plausible," said the researchers, "given that vitamin A is known to scavenge singlet oxygen, and as singlet oxygen contributes to the formation of lipid hydroperoxides, the removal of singlet oxygen prevents lipid peroxidation."
"Future prospective studies with larger numbers and longer follow-up will be useful to establish whether antioxidants are potential, modifiable factors that could reduce the incidence of age-related hearing loss.
"There is also a need for high-quality randomized controlled trials of long duration to determine whether auditory benefits are derived from treatment with antioxidants," they added.
The Journal of Nutrition, Health & Aging; Published online ahead of print.
