A new study shows that people with high blood pressure need to limit their daily coffee consumption-if they drink two or more cups of coffee a day, they may increase their risk of premature death from cardiovascular disease.
There does not appear to be such a risk if only one cup of coffee is consumed daily, according to the study published Dec. 21 in the American Heart Association.
The findings may support the idea that people with severe hypertension should avoid drinking too much coffee, senior study author Dr. Hiroyasu Iso said in the statement. Dr. Iso is a professor in the department of social medicine at Osaka University and director of the Institute for Global Health Policy at the National Center for Global Health and Medicine in Tokyo.
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Previous studies have suggested that coffee can help protect the health of heart disease patients, and even recommended drinking a cup of coffee a day to reduce the risk of death from cardiovascular disease. However, Isohiro Yasushi’s team found that for patients with severe hypertension, the harm of caffeine may outweigh the protective effect of coffee and may increase the risk of death.
What is “severe” hypertension?
Blood pressure can be divided into five levels: the ideal normal standard is less than 130/85, higher than normal is 130-139/85-89, first-level hypertension is 140-159/90-99, second-level hypertension is 160-179/100-109, and third-level hypertension is higher than 180/110. Among them, the second and third-level blood pressure conditions are considered “severe” hypertension.
The study tracked about 18,600 Japanese men and women aged 40 to 75 for about 19 years, and recorded a total of 842 deaths from heart disease; participants were required to report the amount of coffee and green tea they drank each day. The levels of coffee consumption were divided into: occasional or no coffee consumption, less than 1 cup per day, 1 cup, 2 cups and more. Green tea consumption was divided into: occasional or no coffee consumption, less than 1 cup per day, 1 cup or 2 cups, 3 to 4 cups, 5 to 6 cups, 7 cups and more.
The study found that coffee consumption was only associated with an increased risk of heart disease in those with “severe” high blood pressure. Compared with non-coffee drinkers, those who consumed two or more cups of coffee a day had twice the risk of heart disease.
The study did not find an association between green tea consumption and death from heart disease in any blood pressure group.
More research is needed in different groups to confirm these conclusions, said another study author, Dr. Masayuki Teramoto of the University of California, San Francisco.
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Critics: Study has limitations
Some critics believe that the study itself has limitations. First, people who drink a lot of coffee may also have several other risk factors, such as smoking, drinking, and eating less vegetables. Second, the total number of deaths from cardiovascular disease and the number of patients with hypertension among the participants in the study were too small to draw general conclusions about the potential benefits and harms of coffee. For example, only 19 of the 842 deaths (2%) were in the severe hypertension group.
The third is that the data used by the researchers relied on participants to correctly recall and report the amount of coffee or tea they drank. In addition, the researchers did not know whether the participants added sugar or cream to their coffee drinks.
There are different types of coffee and different preferences. Although everyone consumes coffee, the differences may be huge. According to Everyday Health, Professor Christopher Gardner, chairman of the American Heart Association’s Nutrition Committee, commented on this study and believed that unlike black coffee, mocha coffee, cappuccino coffee, Greek caramel espresso, etc. are all called coffee, but they are “a delivery tool for sugar and saturated fat.”
Gardner added that the study does not conclude that “people should give up coffee completely.” He recommends that if you have severe high blood pressure, do not consume more than two cups of coffee a day until more research results are available.
