For years, there have been arguments and discussions about the actual health benefits and side effects of drinking coffee.
And a new study claims that drinking two or more cups of coffee every day is linked with around twice the risk of premature death in people with severe hypertension from cardiovascular disease.
Although drinking just one cup of coffee a day doesn’t seem to carry the same risk, the study, which was published in the Journal of the American Heart Association, also shows that green tea doesn’t either.
According to director of the Institute for Global Health Policy Research at the National Center for Global Health and Medicine in Tokyo, Dr. Hiroyasu Iso, MD, PhD, MPH, who is also the senior study author, said in a statement, “These findings may support the assertion that people with severe high blood pressure should avoid drinking excessive coffee. To the best of our knowledge, this is the first study to find an association between drinking two or more cups of coffee daily and cardiovascular disease mortality among people with severe hypertension.”
Coffee Can Help Protect Heart Health, With Exceptions
In former research, they linked a cup of coffee a day to a lower risk of so-called “cardiac events” and even deaths from cardiovascular disease in heart attack survivors. Dr. Iso and team believed that from this previous research, they would see that people with severe hypertension would actually benefit from drinking coffee. However, this wasn’t the result.
Dr. Iso said, “Because people with severe hypertension are more susceptible to the effects of caffeine, caffeine’s harmful effects may outweigh its protective effects and may increase the risk of death.”
High Blood Pressure vs Severe High Blood Pressure
According to the American Heart Association, high blood pressure, or hypertension, is what happens when ‘the force of blood pushing against the walls of blood vessels is consistently too high, making the heart work harder to pump blood.’
Meanwhile, blood pressure is measured in millimeters of mercury (mmHg), which is read using two different values. The first one is the pressure of the heart beating, known as systolic, while the second is the pressure as the heart relaxes, known as diastolic.
As for the current guidelines of the American Heart Association and the American College of Cardiology, they classify hypertension as a blood pressure reading that’s ‘130/80 mmHg or higher.’
In the United States, Mayo Clinic states that ‘blood pressure of at least 140/90 is considered serious and blood pressure of at least 180/120 is considered a medical emergency.’
As for this new study, it followed over 18,000 adults in Japan for around two decades. Here, the scientists define severe hypertension as blood pressure of 160/100 mmHg or more.
Heavy Coffee Drinkers Had Cardiovascular Risk Factors Too
As for one limitation of the study, it was that participants who drank the most coffee were also more likely to have several risk factors for developing and dying from cardiovascular disease, such as smoking, drinking alcohol and not eating enough vegetables.
Meanwhile, another limitation to the study was that the total number of deaths caused by cardiovascular disease and the subgroup of these deaths in participants with severe hypertension was also too small to bring about wide conclusions about the potential benefits or harms that come from drinking coffee.
Meanwhile, another drawback was that the study participants were made to remember how much coffee and tea they drank, which meant it wasn’t actually recorded in real time.
It Could Be the Sugar and Saturated Fat in the Coffee Too
In addition, another major limitation is that the researchers also lacked data on how the participants prepared their coffee as well. This meant that they didn’t know if they drank their coffee with sugar or cream, or just drank black coffee of plain green tea.
According to nutrition scientist and professor of medicine at Stanford University in California, Christopher Gardner, PhD, who wasn’t part of the study, said, “Black coffee and mocha-frappa-crap-puccino might both qualify as coffee, but the latter is a sugar and saturated fat delivery vehicle.”
Dr. Gardner adds, “Green tea and boba or bubble tea are similar in terms of both possibly qualifying as tea, but the latter is more of a tea-flavored beverage with sugar and dairy and other additives.”
Coffee and Severe Hypertension: What’s the Bottom Line?
Dr. Gardner explains, “A simple takeaway is that if you do have severe hypertension and enjoy coffee, consider limiting your consumption to one cup a day.”
Notably, Dr. Gardner also shares that the study didn’t share whether people should remove coffee from their diet completely, nor does it suggest that there are actually healthier benefits from switching to tea.
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