New research from Brigham and Women's Hospital (BWH) finds that higher caffeine intake is associated with lower rates of tinnitus, often described as a ringing or buzzing sound in the ear when there is no outside source of the sounds, in younger and middle-aged women. This research is published in the August issue of the American Journal of Medicine.
In this prospective study, which followed more than 65,000 women in the Nurses' Health Study II, researchers tracked self-reported results regarding lifestyle and medical history from these women, aged 30 to 44 years and without tinnitus in 1991. Information on self-reported tinnitus and date of onset was obtained from questionnaires returned in 2009, with cases defined as women who reported symptoms "a few days/week" or "daily." After 18 years of follow up, researchers identified 5,289 cases of reported incident tinnitus.
"We observed a significant inverse association between caffeine intake and the incidence of tinnitus among these women," said Gary Curhan, MD, ScD, senior author of the paper and a physician-researcher in the Channing Division of Network Medicine at BWH and Professor of Medicine at Harvard Medical School.
Specifically, researchers report that when compared with women with caffeine intake less than 150 milligrams/day (approximately one and a half 8-ounce cups of coffee), the incidence of reported tinnitus was 15 percent lower among those women who consumed 450 to 599 mg/day of caffeine. The majority of caffeine consumed among the women was from coffee and the results did not vary by age.
"The reason behind this observed association is unclear," said Curhan. "We know that caffeine stimulates the central nervous system, and previous research has demonstrated that caffeine has a direct effect on the inner ear in both bench science and animal studies. Researchers note that further evidence is needed to make any recommendations about whether the addition of caffeine would improve tinnitus symptoms.