Dietary Supplements for Protection of the Inner Ear

Noise-induced hearing loss (NIHL) is a significant clinical, social, and economic issue. Although it was once thought that virtually all NIHL arose from mechanical damage to sensitive sensory cells in the inner ear, we now know that intense metabolic activity drives the formation of free radicals (short-lived, unstable, highly reactive clusters of atoms) in the inner ear. Studies in animals have clearly shown that free radicals formed during and after noise importantly contribute to NIHL, and many laboratories have demonstrated that free radical scavengers ("antioxidants") reduce NIHL in animal subjects. Investigators at multiple institutions have shown the combination of ß-carotene, vitamins C and E, and magnesium reduces NIHL in animals, and supporting data have been obtained in small Phase I/II clinical trial. Additional investigation is critical to now confirm potential utility of these agents in human subjects.