Millions of people around the world begin their mornings with coffee or tea. These drinks are deeply connected to daily life, helping people wake up, stay focused, and feel more energetic.
The ingredient mainly responsible for this boost is caffeine, a natural stimulant found in coffee beans, tea leaves, chocolate, cola, and many energy drinks.
Caffeine works by stimulating the brain and nervous system. It can make people feel more awake and improve concentration for a short time. But caffeine also affects the body in other ways. It can increase heart rate, raise stress hormone levels, and temporarily increase blood pressure.
Because of these effects, scientists have spent many years trying to understand whether drinking coffee or tea regularly could increase the risk of high blood pressure.
High blood pressure, also called hypertension, is one of the world’s most common health problems. It happens when blood pushes too strongly against the walls of the arteries for a long period of time.
Over time, this extra pressure can damage blood vessels and increase the risk of heart disease, heart attacks, strokes, kidney disease, and other serious health problems.
Many people with high blood pressure do not notice symptoms for years, which is why it is often called a “silent” condition. Understanding lifestyle factors that may influence blood pressure is therefore very important for public health.
A large study published in The European Journal of Nutrition has now provided some surprising findings about coffee, tea, and blood pressure.
The research was led by Choy-Lye Chei and colleagues, who studied more than 63,000 Chinese adults living in Singapore. The participants were between 45 and 74 years old when the study began. Researchers followed them for almost 10 years to examine whether their coffee and tea drinking habits were linked to developing high blood pressure later in life.
At the beginning of the study, between 1993 and 1998, participants answered detailed questions about their lifestyle, diet, and daily beverage intake. Researchers recorded how much coffee and tea people drank and also gathered information about other factors that could influence health, including smoking, physical activity, and diet.
The scientists then tracked participants during follow-up periods between 1999–2004 and 2006–2010.
By the end of the study, 13,658 people had developed high blood pressure.
One of the biggest surprises was the finding related to coffee. People who drank three or more cups of coffee per day actually had a lower risk of developing high blood pressure compared to people who drank about one cup per day.
This result was unexpected because caffeine is known to temporarily raise blood pressure. Scientists originally thought heavier coffee drinking might increase long-term hypertension risk.
Tea, however, showed a different pattern. People who drank black tea or green tea every day had a slightly higher risk of developing high blood pressure compared to those who drank tea less often.
Researchers also studied overall caffeine intake from all sources. They found that people consuming more than 300 milligrams of caffeine daily had a 16% higher risk of developing high blood pressure compared to people consuming less than 50 milligrams per day.
Three cups of coffee can roughly contain around 300 milligrams of caffeine, although the exact amount varies depending on the coffee type and preparation method.
Another interesting finding was that both very low coffee intake and higher coffee intake appeared linked to lower blood pressure risk. People who drank coffee less than once a week and those drinking three or more cups daily both showed lower risk than people drinking only one cup each day.
This suggests that the relationship between coffee and blood pressure may not be simple. The amount, frequency, and even long-term body adaptation to coffee could all play important roles.
Researchers believe coffee may contain substances that help balance out some of caffeine’s negative effects. Coffee beans naturally contain antioxidants and anti-inflammatory compounds that may support heart and blood vessel health.
Antioxidants help protect the body from damage caused by unstable molecules called free radicals. Chronic inflammation and oxidative stress are believed to contribute to heart disease and high blood pressure.
The researchers think these protective compounds in coffee could partly explain why heavier coffee drinkers did not show a higher risk of hypertension in this study.
Tea also contains antioxidants and other healthy plant compounds. However, researchers suggested that the caffeine effect in frequent tea drinkers may have had a stronger influence on blood pressure in this particular study population.
The scientists emphasized that more research is still needed. Results may vary depending on ethnicity, genetics, diet, lifestyle, and even how coffee or tea is prepared in different countries.
For example, adding large amounts of sugar or cream to coffee may affect health differently compared to drinking plain black coffee. Tea varieties also differ widely in caffeine levels and plant compounds.
The researchers said future studies should explore how different preparation methods and individual body responses influence the effects of caffeine on blood pressure.
For now, the study suggests that moderate to high coffee consumption may not be as harmful for blood pressure as many people once believed. At the same time, people should still pay attention to how caffeine affects their own body.
Some people are very sensitive to caffeine and may experience rapid heartbeat, anxiety, poor sleep, or temporary spikes in blood pressure even after small amounts.
Doctors generally recommend moderation and regular blood pressure monitoring, especially for people who already have hypertension or heart disease.
The study’s findings also highlight how complex nutrition research can be. Foods and drinks often contain many different substances that can affect the body in different ways. Coffee, for example, contains hundreds of natural compounds beyond caffeine alone.
As scientists continue studying the long-term effects of coffee and tea, one thing remains clear: daily habits can play an important role in long-term health.
The research findings were published in The European Journal of Nutrition.
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