Women who drink a lot of coffee may be unknowingly protecting themselves against developing the hearing conditions tinnitus, new research has indicated.

A US study has found that tinnitus, a persistent ringing or buzzing in the ears, is less likely to occur in women who consumed the most caffeine.

Current tinnitus treatment guidelines often advise sufferers to cut out out caffeine consumption. It is not yet clear following the new research how caffeine can protect against tinnitus.

Researchers at Brigham and Women's Hospital in Boston looked at data on more than 65,000 nurses taking part in a major health study. The women were in their 20s to their 40s in 1991 and none had tinnitus then. They filled out diet questionnaires every four years during the research.

In 2009, the participants were asked if they had ringing or buzzing in their ears during the previous year. The researchers found that 5,289 women reported having those symptoms a few days a week or every day.

On average, the women consumed about 242 milligrams of caffeine per day, which is equal to about three eight ounce cups of coffee. The researchers said women who had higher caffeine intake, usually through coffee, had a lower risk of subsequently developing tinnitus than those with the lowest caffeine intake.

The incidence of tinnitus was 15% lower among women who consumed 450 to 599 mg/day of caffeine, equivalent to 6-8 cups of coffee, compared to the women who consumed less than 150 milligrams per day - around half a cup.

The study could not prove conclusively that caffeine protects some women from developing tinnitus, nor is it clear yet whether tinnitus sufferers should boost their caffeine consumption to ease their condition.

The research was published in The American Journal of Medicine.

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