There’s no question that coffee has some great health benefits.
It can improve longevity, protect against liver disease, help control appetite, lower the risk of depression, boost alertness and memory and reduce the risk of developing type 2 diabetes.
And for people with diabetes, coffee can greatly reduce the risk of death from all causes.
But there is one area where studies of coffee’s benefits have produced mixed results…
Previous research has shown that one daily cup of coffee may help heart attack survivors by lowering their risk of death after a heart attack. Drinking a cup of coffee a day may also prevent heart attacks or strokes in healthy individuals, and two cups a day can lower heart failure risk by 30 percent.
On the flip side, drinking too much coffee can raise blood pressure and lead to heart palpitations, both of which can negatively impact your heart health.
So it’s obviously important to know how much is too much…
Researchers in Japan decided to conduct a study to determine the impact drinking different amounts of coffee has on people with varying degrees of high blood pressure and compare that with the effects of green tea in the same population. What they discovered clarified a few things.
High blood pressure (or hypertension) occurs when the force of blood pushing against the walls of your blood vessels is consistently too high. This makes the heart work harder to pump blood and can lead to a number of heart complications.
According to the American Heart Association and the American College of Cardiology, the current guideline for hypertension is a blood pressure reading of 130/80 or higher.
However, for the Japanese study, researchers classified blood pressure into five categories:
- Optimal and normal (less than 130/85 mm Hg)
- High normal (130-139/85-89 mm Hg)
- Grade 1 hypertension (140-159/90-99 mm Hg)
- Grade 2 hypertension (160-179/100-109 mm Hg)
- Grade 3 hypertension (higher than 180/110 mm Hg)
Blood pressure measurements falling in grades 2 and 3 were categorized as severe hypertension.
The study drew from participants in a large-scale cohort study during which data was gathered through health exams and self-administered questionnaires on diet, lifestyle and medical history. The data was provided over nearly 19 years of follow-up.
The analysis found no association between one daily cup of coffee and an increased risk of death from cardiovascular disease across any blood pressure categories. There also was no link in any blood pressure category between green tea consumption and increased cardiovascular disease mortality risk.
However, that changed with a 2nd cup of joe …
People with severe hypertension who consumed two or more daily cups of coffee had twice the risk of cardiovascular disease death compared with individuals who did not drink any coffee.
“To the best of our knowledge, this is the first study to find an association between drinking 2 or more cups of coffee daily and cardiovascular disease mortality among people with severe hypertension,”
”These findings may support the assertion that people with severe high blood pressure should avoid drinking excessive coffee,” says the study’s senior author Dr. Hiroyasu Iso, director of the Institute for Global Health Policy Research, Bureau of International Health Cooperation, National Center for Global Health and Medicine in Tokyo and professor emeritus at Osaka University.
“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,” Iso says.
So if your blood pressure is 160/100 mm Hg or higher, you’ll want to limit your coffee to one cup a day. And if you need another warm beverage to fill that void, consider tea.
The study found that one cup of coffee and daily green tea consumption did not increase the risk of death related to cardiovascular disease in any blood pressure category.
An 8-ounce cup of green or black tea has 30-50 milligrams of caffeine, and an 8-ounce cup of coffee has closer to 80 to 100 milligrams.
Sources:
Drinking 2 or more cups of coffee daily may double risk of heart death in people with severe hypertension — American Heart Association
Coffee and Green Tea Consumption and Cardiovascular Disease Mortality Among People With and Without Hypertension — Journal of the American Heart Association