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The Role of Diet in Tinnitus and Hearing Health A healthy diet and lifestyle are our best weapons in the prevention of cardiovascular disease, but what about their impact on preserving hearing health and lessening the impact of tinnitus? To explore this topic, the ATA talked to Christopher Spankovich, PhD, an expert in this field. Joy Onozuka (JO): We all understand the importance of eating a well-balanced healthy diet to optimize our long-term physical and mental health. Based on your research, is there sufficient evidence to propose a healthy hearing diet? Christopher Spankovich (CS): Our diets do indeed influence our hearing health similar to how our diets influence our overall health and risk for chronic disease. Yet, the relationship of diet and specific nutrients in susceptibility to hearing loss and tinnitus (as with other acquired disorders) is complicated and influenced by an array of factors (which influence each other) such as our genetics, environment (including noise exposure), physical activity, lifestyle, and of course our overall health status (both physical and mental). For example, individuals with type 2 diabetes have significantly increased odds www.ATA.org
of hearing loss. The cascade of biochemical effects created by diabetes can lead to glycation, protein and lipid dysfunction, nitric oxide and glutathione dysregulation, glutamate excitotoxicity, and microangiopathy. It is also likely that an individual who develops type 2 diabetes has dietary and physical activity factors that exacerbate risk for further pathology. Most of our information on specific nutrients and risk for acquired hearing loss comes from animal models, primarily rodents. This presents a limitation, as animals do not necessarily share the same bioavailability of nutrients; species can vary in regard to how they metabolize, utilize, and excrete nutrients. Let’s consider vitamin C. Vitamin C is an essential nutrient in humans (dietary required) and has numerous roles in our cells: it serves as an enzyme for synthesis of neurotransmitter and neuropeptide hormones, is a cofactor in the hydroxylation and maturation of collagen (healing of musculoskeletal tissue), is an important water-soluble antioxidant, and helps to keep vitamin E in a reduced state. Most rodents (with the exception of guinea pigs) endogenously synthesize vitamin C, meaning they do not require a dietary source. This is all related to a specific
gene that encodes L-gulonolactone oxidase (GULO); primates (which include humans) had a mutation in the gene that encodes GULO about 30 Ă— 106 years ago, so we need vitamin C from exogenous sources (e.g., food). Therefore, a rat model may not be the best to look at dietary vitamin C and hearing outcomes, since their cells make vitamin C on their own. In general, research has focused on nutrients with antioxidant, antiinflammatory, or anti-ischemic properties. Perhaps the simplest dietary change that appears to affect susceptibility to hearing loss is caloric intake. Simply restricting caloric intake can significantly reduce evidence of hearing loss and lead to increased longevity in a number of rodent models, but evidence in primates is still under study. Caloric restriction studies often reduce overall calorie intake by approximately 30 percent compared to normal intake but maintain adequate nutrient intake to avoid malnutrition. Other dietary factors that have been considered include macronutrient intake (fats, carbohydrates, protein) and various micronutrients (e.g., B vitamins, vitamins C and E) and minerals TINNITUS TODAY SUMMER 2020
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