Coffee and tea are among the most popular drinks in the world. Millions of people start their morning with a hot cup because these drinks help them feel awake, focused, and ready for the day.
Their stimulating effect comes mainly from caffeine, a natural substance found in coffee beans, tea leaves, chocolate, cola drinks, and many energy drinks.
While caffeine can improve alertness and reduce tiredness, it also affects the heart and blood vessels. For many years, scientists have wondered whether drinking coffee or tea regularly increases the risk of developing high blood pressure.
High blood pressure, also called hypertension, is one of the leading causes of heart disease, stroke, kidney disease, and early death. It develops when the force of blood pushing against the walls of the arteries stays too high for a long time.
Because hypertension often causes no symptoms, many people do not realize they have it until serious health problems appear. Understanding whether everyday habits such as drinking coffee or tea influence blood pressure is therefore important for public health.
A large study led by Choy-Lye Chei and colleagues explored this question. The research was published in The European Journal of Nutrition and included more than 63,000 Chinese adults living in Singapore who were between 45 and 74 years old.
The participants were followed for nearly 10 years, making this one of the largest long-term studies to examine the relationship between caffeine, coffee, tea, and blood pressure.
At the beginning of the study, between 1993 and 1998, participants answered detailed questions about how much coffee and tea they usually drank, along with information about their diet, lifestyle, exercise, smoking habits, and overall health.
The researchers then continued to monitor their health during two follow-up periods from 1999 to 2004 and from 2006 to 2010. By the end of the study, 13,658 participants had developed high blood pressure.
The findings were more complicated than many people expected. People who drank three or more cups of coffee each day actually had a lower risk of developing high blood pressure than those who usually drank one cup per day.
This suggests that coffee itself may not increase blood pressure in the long term and may even provide some protective effects for certain people.
The results for tea were different. People who drank black tea or green tea every day had a slightly higher risk of developing high blood pressure than people who drank tea less often. However, the increase in risk was relatively small, and the study could not prove that tea directly caused hypertension.
The researchers also calculated each person’s total caffeine intake from all sources. They found that people consuming more than 300 milligrams of caffeine each day, roughly equal to three or more cups of coffee depending on the strength of the drink, had a 16% higher risk of developing high blood pressure compared with people consuming less than 50 milligrams each day.
One particularly interesting finding was that both people who rarely drank coffee and those who drank three or more cups daily appeared to have a lower risk of hypertension than people who usually drank only one cup each day.
This unusual pattern suggests that the relationship between coffee and blood pressure is more complex than simply saying that more coffee is either good or bad.
Scientists think the explanation may lie in the many natural compounds found in coffee besides caffeine. Coffee contains hundreds of chemicals, including antioxidants and anti-inflammatory compounds that may improve blood vessel function and reduce inflammation.
These beneficial substances could partly balance or even outweigh caffeine’s short-term effect on raising blood pressure. Tea also contains beneficial antioxidants, but differences in caffeine content, preparation methods, and drinking habits may help explain why the results were different.
The researchers emphasized that this was an observational study. It found associations but could not prove that coffee or tea directly caused or prevented high blood pressure. More studies involving different populations and eating habits will be needed to better understand these relationships.
For now, the findings suggest there is no simple answer to whether coffee is harmful or helpful for blood pressure. People respond differently to caffeine, and factors such as genetics, overall diet, exercise, body weight, smoking, and existing medical conditions also affect blood pressure.
If you have hypertension or are concerned about your caffeine intake, it is a good idea to discuss your drinking habits with your healthcare provider. Paying attention to how your body responds while maintaining a healthy lifestyle remains one of the best ways to protect your heart.
If you care about blood pressure, please read studies about how diets could help lower high blood pressure, and 3 grams of omega-3s a day keep high blood pressure at bay.
For more health information, please see recent studies about how tea and 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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