Over the past year, the health benefits of coffee have gotten a lot of attention. Now it is time for black tea to take the spotlight. An epidemiological study suggests that people who drink a hot cup of tea every day are less likely to develop glaucoma than those who don’t like the stuff (Wu et al, British Journal of Ophthalmology, Dec. 14, 2017). Iced tea, decaf tea, herbal tea and soft drinks don’t seem to have the same association.
What Is It About a Cup of Tea?
Tea drinkers were about 74 percent less likely to have glaucoma, an eye disease in which excessive pressure inside the eye harms the optic nerve. It is possible that the flavonoid antioxidant compounds found in tea might be responsible, at least in part. Previous studies have shown that such flavonoids are associated with slowing vision loss due to glaucoma (Patel et al, Graefe’s Archive for Clinical and Experimental Ophthalmology, Nov. 2015).
The data for the current study came from the National Health and Nutrition Examination Survey (NHANES) of 2005 to 2006. There were about 10,000 individuals participating in all of NHANES, but 1,678 people were included in this part of the survey. Five percent of them had glaucoma. The researchers were able to consider data on diet as well as on health conditions to tease out this association.
Should You Start Drinking a Cup of Tea?
Such epidemiological data can never prove cause and effect relationships. All they show are associations. There is a possibility that something else sets tea drinkers apart and has a benefit for eye health.
The authors call for larger, prospective studies of tea drinking and the risk of glaucoma. That said, a hot cup of tea a day poses little risk and just might offer benefits for eye health. Plus, many of us find it tasty and relaxing.
If you would like to learn more about glaucoma and other conditions that affect your eyes, you may wish to listen to our interview with ophthalmologist Peter J. McDonnell. It is Show 1050: How to Protect Your Vision.