A study of more than 18,600 men and women in Japan was conducted
Drinking two or more cups of coffee a day may double the risk of death from cardiovascular disease among people with severe high blood pressure (160/100 mm Hg or higher) but not people with high blood pressure not considered severe, according to research published recently in the Journal of the American Heart Association.
In contrast, the study found that one cup of coffee and daily green tea consumption did not increase the risk of death related to cardiovascular disease at any blood pressure measurement, though both drinks contain caffeine. According to the FDA, 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.
Previous research found that drinking one cup of coffee a day may help heart attack survivors by lowering their risk of death after a heart attack and may prevent heart attacks or strokes in healthy individuals. In addition, separate studies have suggested drinking coffee regularly may reduce the risk of developing chronic illnesses, such as Type 2 diabetes and some cancers; may help to control appetite; may help to lower the risk of depression or boost alertness, though it is not clear if this effect is from the caffeine or something else in coffee. On the harmful side, too much coffee may raise blood pressure and lead to anxiety, heart palpitations and difficulty sleeping.
Further study is needed, researchers said, to learn more about the effects of coffee and green tea consumption in people with high blood pressure and to confirm the effects of coffee and green tea consumption in other countries.
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