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A new study has found that taking two or more cups of coffee daily could increase the risk of death among people with severe hypertension. According to experts, severe hypertension is a blood pressure above 160/90mmHg. This finding did not apply to people with non-severe hypertension.

The study also showed that taking one cup of coffee with green tea daily did not increase the risk of heart disease regardless of blood pressure even though both beverages have caffeine. The team speculated that this was because black or green tea had less caffeine than coffee.

The team conducted the study after a previous study that showed that coffee drinking could prevent heart attacks in people who had previously experienced heart attacks and others who were healthy. They wanted to know if the results could apply to people with hypertension.

How researchers conducted the study

The researchers used over 12,000 female participants and about 6750 male participants between the age of 40 and 79. These participants came from a study conducted between 1988 and 1990 among people living in 45 Japanese communities. Researchers gave them physical examinations and questionnaires to assess medical history, diet, and lifestyle 

The follow-up occurred for 19 years. During this duration, the researchers counted 842 deaths from heart disease. They concluded that consuming over two cups of coffee daily had a link to heart disease among people with severe blood pressure. However, drinking one cup of coffee daily or green tea did not increase the risk of death from heart disease.

The study also showed that coffee consumption was more prevalent among certain groups, including young adults, drinkers, smokers, and those who ate fewer vegetables. It was also common among people with lower systolic blood pressure and higher cholesterol.

Limitations of the study

The researchers acknowledge that there were limitations in the study. For instance, they only measured blood pressure once and did not account for its changes over time. Moreover, the study relied on self-reporting for tea and coffee consumption. As the study was international, researchers cannot directly link coffee consumption to cardiovascular diseases.

The team recognizes that they need to do more research to investigate the effect of green tea and coffee consumption among people with hypertension.