That third or fourth cup of coffee may do more than make your heart race: New research suggests it could significantly increase your risk of glaucoma if you're genetically predisposed to the eye disease.
The study included more than 120,000 British people, aged 39 to 73, who provided information about their caffeine consumption and their vision, including whether they had glaucoma or a family history of the disease, which is the leading cause of blindness in the United States.
After three years, the researchers assessed the participants' eyes, including their intraocular pressure (IOP), which is pressure inside the eye. Elevated IOP is a risk factor for glaucoma.
High caffeine consumption was not associated with an increased risk for elevated IOP or glaucoma overall, but in participants with the strongest genetic predisposition to elevated IOP, greater caffeine consumption was associated with higher IOP and higher glaucoma rates.
Those who consumed the most caffeine - about four cups of coffee daily - had a 0.35 mm Hg higher IOP.
People in the highest genetic risk score category for glaucoma who consumed more than roughly three cups of coffee a day had a 3.9-fold higher rate of glaucoma than those who consumed no or minimal caffeine and were in the lowest genetic risk score group, the findings showed.
The study, published in the June issue of the journal Ophthalmology, is the first to show a dietary/genetic interaction in glaucoma, and suggests that people with strong family history of glaucoma should limit caffeine intake, according to the authors.
"We previously published work suggesting that high caffeine intake increased the risk of the high-tension open angle glaucoma among people with a family history of disease," said study lead and corresponding author Dr. Louis Pasquale. He is deputy chair for ophthalmology research at Mount Sinai Health System in New York City.
"In this study, we show that an adverse relation between high caffeine intake and glaucoma was evident only among those with the highest genetic risk score for elevated eye pressure," Pasquale said in a Mount Sinai news release.
According to study co-author Dr. Anthony Khawaja, an associate professor of ophthalmology at University College London, "Glaucoma patients often ask if they can help to protect their sight through lifestyle changes, however this has been a relatively understudied area until now. This study suggested that those with the highest genetic risk for glaucoma may benefit from moderating their caffeine intake."
Still, Khawaja added, "It should be noted that the link between caffeine and glaucoma risk was only seen with a large amount of caffeine and in those with the highest genetic risk."
The U.S. National Eye Institute has more on glaucoma.
SOURCE: Mount Sinai Health System, news release, June 7, 2021