Lifestyle and normal hearing function in Italy and Central Asia: The potential role of coffee

Background: Sound perception has a fundamental role of the auditory system and its absence causes hearing loss. It is well known that normal hearing function as well as the non-Mendelian forms of hearing impairment (i.e. age-related and noise-induced hearing loss) are considered to be due to both genetic and lifestyle/environmental factors. To date, few factors have been hypothesized as being related to normal hearing function and to age-related and noise-induced hearing loss. Method: We describe a broad study carried out on 4401 subjects from isolated populations (located from Italy to Central Asia) aimed at the identifi cation of lifestyle/environmental factors (focused mainly on diet) that are potentially associated with normal hearing function (i.e. quantitative trait). Results: Our results show, for the fi rst time, that among eight analysed variables (smoking, chocolate, coffee, tea, wine, beer, dairy products, spirits), only coffee consumption and coffee intake showed a signifi cant association with better hearing function in four out of the 11 countries investigated. In particular, coffee consumption was associated over an audiometric profi le from low (250, 500, 1000 Hz) to high (4000, 8000 Hz) frequencies: p -value 0.006 in southern Italy, p -value 0.017 in Azerbaijan, p -value 0.016 in Tajikistan at low frequencies and p -value 0.038 in Sardinia at high frequencies. With regard to intake, we detected an association only at high frequencies (2 cups/day, p -value 0.01; 3 cups/day, p -value 0.003). Conclusion: A possible explanation might be the antioxidant content of coffee, the concentration of which is higher than red wine or herbal teas. A possible additional reason could be a specifi c protective effect of active coffee compounds such as trigonelline. The fi ndings provide a better knowledge of environment/lifestyle factors related to the hearing system and might help in defi ning new preventive strategies for hearing loss