The risk of glaucoma—a condition that can result in partial or total eyesight loss—was lower in people who drank hot tea every day, according to a study published in the British Journal of Ophthalmology.
Researchers evaluated the association between consumption of coffee, tea, or soft drinks and glaucoma in the participants of the 2005–06 National Health and Nutrition Examination Survey (NHANES). Among those who consumed at least one cup of hot tea per day, the odds of having glaucoma were 74 percent lower than those of non-tea drinkers, according to the study.
Some past research has found that coffee drinkers have a higher risk of glaucoma, while other research has shown the opposite, Dr. Anne Coleman, lead researcher and director of the UCLA Mobile Eye Clinic, said in an article in Consumer Reports.
“In this recent study, however, there were no links observed between coffee consumption and glaucoma. Hot tea, however, was found to have a potential benefit. (Iced tea, decaffeinated iced tea and any kind of soda appeared to have no connection to changing one’s glaucoma risk.),” according to the article.
While the study shows an association between tea drinking and lower glaucoma risk, it does not prove that tea is preventive against the disease.
“There may be other lifestyle factors with these daily tea drinkers that we’re not accounting for here,” Coleman told Consumer Reports.
The researchers said they chose the 2005–06 survey because that year 1,678 participants agreed to share full eye test results.
Glaucoma, a disease of the eye’s optic nerve, affects about 3 million Americans and is a leading cause of blindness, according to the National Eye Institute. In 2010 alone, 1.9 percent of the North American population age 40 and older was diagnosed with some form of glaucoma.