New York, Nov 19 (IANS): Researchers have found that eating a healthy diet may reduce the risk of acquired hearing loss.

Using longitudinal data collected in the Nurses' Health Study II Conservation of Hearing Study (CHEARS), researchers from Brigham and Women's Hospital in US, examined three-year changes in hearing sensitivities and found that women whose eating patterns adhered more closely to commonly recommended healthful dietary patterns have substantially lowered risk of decline in hearing sensitivity.

"A common perception is that hearing loss is an inevitable part of the aging process. However, our research focuses on identifying potentially modifiable risk factors - that is, things that we can change in our diet and lifestyle to prevent hearing loss or delay its progression," said lead author Sharon Curhan.

"The benefits of adherence to healthful dietary patterns have been associated with numerous positive health outcomes and eating a healthy diet may also help reduce the risk of hearing loss," Curhan added.

Previous studies have suggested that higher intake of specific nutrients and certain food, such as the carotenoids beta-carotene and beta-cryptoxanthin (found in squash, carrots, oranges and other fruits and vegetables) were associated with lower risk of self-reported hearing loss.

For the study published in the American Journal of Epidemiology, the researchers established 19 geographically diverse testing sites across the US and trained teams of licensed audiologists to follow standardised CHEARS methods.

The audiologists measured changes in pure-tone hearing thresholds, the lowest volume that a pitch can be detected by the participant in a given ear, over the course of three years.

An audiologist presented tones of different frequencies (0.5, 1 and 2 kHz as low-frequencies; at 3 kHz and 4 kHz as mid-frequencies; and at 6 kHz and 8 kHz as higher frequencies) at variable "loudness" levels and participants were asked to indicate when they could just barely hear the tone.

Using over 20 years of dietary intake information that was collected every four years beginning in 1991, the researchers investigated how closely participants' long-term diets resembled some well-established and currently recommended dietary patterns, such as the DASH diet, the Mediterranean diet, and Alternate Healthy Index-2010 (AHEI-2010).

Greater adherence to these dietary patterns has been associated with a number of important health outcomes, including lower risk of heart disease, hypertension, diabetes, stroke and death as well as healthy aging.

The team found that the odds of a decline in mid-frequency hearing sensitivities were almost 30 per cent lower among those whose diets most closely resembled these healthful dietary patterns, compared with women whose diets least resembled the healthy diet. In the higher frequencies, the odds were up to 25 per cent lower.

"The association between diet and hearing sensitivity decline encompassed frequencies that are critical for speech understanding," said Curhan.

"We were surprised that so many women demonstrated hearing decline over such a relatively short period of time," Curhan added.