Many people enjoy starting their day with a cup of coffee or tea. These popular drinks contain caffeine, a natural substance that gives you a boost of energy and helps you feel more alert. But caffeine also affects your heart and blood pressure, and scientists have been trying to understand whether drinking coffee or tea could raise the risk of high blood pressure.
A recent study by Choy-Lye Chei and colleagues, published in The European Journal of Nutrition, looked closely at this question. The research followed more than 63,000 Chinese adults in Singapore, aged 45 to 74, over nearly 10 years. The goal was to see how their coffee and tea drinking habits might be linked to their chances of developing high blood pressure.
High blood pressure, or hypertension, is a serious health condition that increases the risk of heart disease and stroke. It happens when the force of the blood pushing against the walls of your arteries stays too high for a long time.
Caffeine, found in coffee, tea, cola, chocolate, and energy drinks, affects the body in several ways. It stimulates the brain, heart, and muscles. It also raises levels of hormones like cortisol and adrenaline, which can increase blood pressure.
In this study, researchers collected information from participants between 1993 and 1998 about how much coffee and tea they drank, along with details about their overall lifestyle. They then followed up with these individuals during two time periods: 1999–2004 and 2006–2010. By the end of the study, 13,658 participants had developed high blood pressure.
Surprisingly, the results showed that people who drank three or more cups of coffee per day had a lower risk of developing high blood pressure compared to those who drank only one cup per day.
But when it came to tea, the findings were different. Daily drinkers of black or green tea had a slightly higher risk of developing high blood pressure than those who drank tea less often.
The researchers also looked at how much caffeine people consumed in total. They found that people who consumed more than 300 milligrams of caffeine per day (about three or more cups of coffee) had a 16% higher risk of high blood pressure compared to those who consumed less than 50 milligrams per day.
One interesting discovery was that drinking either very little coffee (less than one cup a week) or three or more cups per day seemed to be linked to a lower risk of high blood pressure. In contrast, people who drank only one cup per day had a slightly higher risk. This suggests that the amount and frequency of coffee consumption might play an important role.
The study authors believe that while caffeine might raise blood pressure, other compounds in coffee—especially when consumed in higher amounts—could cancel out this effect and even offer some protection.
These beneficial compounds might include antioxidants or anti-inflammatory substances found in coffee beans. Tea also contains helpful substances, but the higher caffeine levels in frequent tea drinkers might have a stronger influence on blood pressure.
The researchers say more studies are needed to understand exactly how coffee and tea affect blood pressure, especially in people from different backgrounds or with different diets.
In the meantime, this study shows that your daily habits—like how often and how much coffee or tea you drink—may affect your blood pressure risk. It’s a good idea to pay attention to how your body responds to caffeine and to talk with your doctor if you have concerns about high blood pressure or your caffeine intake.
If you care about blood pressure, please read studies that black licorice could cause dangerous high blood pressure, and this common plant nutrient could help reduce high blood pressure.
For more information about blood pressure, please see recent studies about how coffee influence your risk of high blood pressure, and results showing this olive oil could reduce blood pressure in healthy people.
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