Millions of people across the world start their day with a cup of coffee. 85% of Americans drink at least one caffeinated beverage daily. In the UK, tea is the caffeinated beverage of choice, with around 100 million cups of tea drunk by Britons each day. Tea-drinking is a part of the culture there, just as it is in other countries, like Japan.
For many, drinking coffee, tea, or another caffeinated beverage gives us a jolt to be more alert throughout the day or even to kickstart the metabolism in the morning. But drinking caffeine may also have negative effects for some, particularly those with a family history of glaucoma.
How Is Caffeine Linked to Inherited Glaucoma?
Researchers have found that caffeine can result in an increased risk of glaucoma. This increased risk is only present for people who are already more likely to develop glaucoma due to genetics. While the link isn’t necessarily a strong one, the researchers suggested that anyone with a family history of glaucoma may want to reduce their caffeine intake if they’re looking for ways to decrease their risk of developing glaucoma.
What Causes Glaucoma?
Glaucoma isn’t just one eye disease. Glaucoma is actually an umbrella term for several different conditions that can damage the eye’s optic nerve. Most frequently, this damage is the result of increased pressure in the eye. In the most common types of glaucoma, eye pressure is caused by a buildup of fluid in the eye because fluid isn’t properly draining.
How Does Caffeine Cause an Increased Risk of Inherited Glaucoma?
Researchers discovered that caffeine in large amounts could increase eye pressure temporarily. Because eye pressure is a known cause of glaucoma, the researchers studied the effect further. In their studies, they examined the records of upwards of 100,000 different participants. These medical records included caffeine intake, eye pressure, genetic information, and whether the patient had glaucoma.
The researchers discovered from the study that there wasn’t an increased risk of glaucoma with caffeine intake in general. In fact, despite the temporary increase in eye pressure, caffeine intake was often associated with a decrease in overall eye pressure. However, when the researchers specifically looked at the records of those who had a genetically increased risk of glaucoma, they noticed a pattern. People who already had an increased risk of glaucoma due to genetic factors experienced an increased risk of glaucoma from high caffeine consumption.
How Much Does Caffeine Increase the Risk of Glaucoma?
The researchers found that those with an inherited risk of glaucoma could experience an increased risk of glaucoma if they consumed a large amount of caffeine. The people in the study who were at the greatest risk of glaucoma consumed 321mg or more of caffeine every day. About three cups of coffee contains 321mg of caffeine, depending on the size of the coffee cups.