Cholesterol intake linked to hearing loss
MedWire News: A diet high in cholesterol could have adverse effects on hearing, whereas treatment with statins and consumption of monounsaturated fats may have beneficial effects, say researchers.
"Our data indicate that the type of diet eaten rather than serum lipid concentrations could directly or indirectly influence the hearing function among older adults," writes the Australian team in The Journal of Nutrition.
Paul Mitchell (University of Sydney) and colleagues analyzed data on nearly 3000 participants (aged ≥50 years) of the Blue Mountains Hearing Study.
Hearing impairment was defined as the pure-tone average (PTA) of audiometric hearing thresholds at 500, 1000, and 4000 Hz (PTA0.5-4 KHz), and a PTA0.5-4 KHz greater than a 25 dB hearing level in the better of the two ears. Dietary intake was assessed using a food frequency questionnaire.
The researchers report that 32% (n=784) of study participants had hearing loss.
The odds for having hearing loss increased significantly across increasing quartiles of dietary cholesterol intake, with those in the highest quartile (median intake 390 mg/day) having a 33% increased likelihood of prevalent hearing loss compared with those in the lowest quartile (190 mg/day).
In contrast, statin use, which was self-reported by 9% (n=274) of participants, was associated with a 48% reduction in risk for hearing loss. The findings also suggest that statin dosage influences the risk for hearing loss, with individuals in the second tertile of statin dose, having a 67% reduced odds for hearing loss compared with those in the first.
When the researchers examined the association between dietary variables and the 5-year incidence of hearing loss, they found that monounsaturated fats appeared to have a protective effect. Specifically, participants in the second (median intake 24.7 g/day) and third (27.8 g/day) quartiles of dietary monounsaturated fatty acid intake had a respective 61% and 49% lower 5-year risk of hearing loss progression than those in the first quartile (20.4 g/day).
The intake of other dietary fats and food groups showed no significant associations with hearing loss progression, the authors note.
"The current study findings add to our previous body of work demonstrating that preserving optimal hearing among older adults could be as simple as maintaining a healthy diet," say Mitchell and co-authors.
They conclude: "Dietary fat modification may provide a method for potential prevention of sensorineural hearing loss, but this requires further confirmation by other large, population-based studies."
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By Nikki Withers