A new study finds that women who consume more caffeine are less likely to have tinnitus - a condition where a person perceives noise in one or both ears, or in the head, even though there is no external sound.
The researchers, from Brigham and Women's Hospital (BWH) in Boston, MA, write about their findings in The American Journal of Medicine.
According to the American Tinnitus Association, around 50 million people in the US experience some degree of tinnitus, which is often described as "ringing in the ears" although some people also hear hissing, buzzing, roaring, clicking or chirping. Of these, about 1 million are so badly affected they cannot function normally day to day.
For the study, the researchers analyzed data on over 65,000 women with and without tinnitus from the Nurses' Health Study II.
The women were aged between 30 and 44 at the start of the study in 1991, when researchers collected a wealth of information on medical history, lifestyle and diet. At this point, the average caffeine intake was 242.3 mg per day - the equivalent of nearly two and a half 8-ounce cups of coffee. Most of the caffeine consumed came from coffee drinking.
In 2009, 18 years after they joined the study, the women were asked questions about tinnitus, including date of onset, where applicable. When a woman reported experiencing symptoms either daily or on a few days per week, the researchers counted it as a case. They identified a total of 5,289 cases of reported incident tinnitus.
Women who consumed more caffeine less likely to be among tinnitus cases
When they analyzed the results, the team found the more caffeine women consumed, the less likely they were to be among the tinnitus cases.
Senior author Gary Curhan, a physician-researcher in BWH's Channing Division of Network Medicine and professor of Medicine at Harvard Medical School, says:
"We observed a significant inverse association between caffeine intake and the incidence of tinnitus among these women."
He and his and colleagues found that regardless of age, rates of tinnitus were 15% lower among women who consumed 450-599 mg a day of caffeine, compared with women who drank less than 150 mg a day (about one and a half 8-ounce cups of coffee).
Prof. Curham notes that while the reason behind the finding is unclear, 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."
The researchers say more evidence is required before we can say whether increased caffeine intake might improve tinnitus symptoms.
Funds from the National Institutes of Health helped finance the study.
Medical News Today recently reported on another study where researchers found tinnitus affects processing of emotions. Writing in the journal Brain Research, they describe how, compared with people not affected by the condition, those with tinnitus process emotions differently in the brain.