High blood pressure, also known as hypertension, occurs when the force of blood pushing against the walls of blood vessels is consistently too high, making the heart work harder to pump blood. It is measured in millimeters of mercury (mm Hg). The current blood pressure guidelines from the American Heart Association and the American College of Cardiology classifies hypertension as a blood pressure reading of 130/80 mm Hg or higher.
The blood pressure criteria for this study are slightly different from the ACC/AHA guidelines. 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 (160-179/100-109 mm Hg); and grade 3 (higher than 180/110 mm Hg). Blood pressure measures in grades 2 and 3 were considered severe hypertension in this study.
Study participants included more than 6,570 men and more than 12,000 women, ages 40 to 79 years at the start of the research. Participants provided data through health examinations and self-administered questionnaires assessing lifestyle, diet and medical history.
Coffee and Patients with High Blood Pressure
During nearly 19 years of follow-up (through 2009), 842 cardiovascular-related deaths were documented. It was found that drinking two or more cups of coffee a day was associated with twice the risk of cardiovascular disease death in people whose blood pressure was 160/100 mm Hg or higher compared to those who did not drink any coffee. Drinking one cup of coffee a day was not associated with increased risk of death from cardiovascular disease across any blood pressure categories. Green tea consumption was not associated with an increased risk of cardiovascular disease mortality across any blood pressure categories.
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Previous studies have demonstrated that drinking one cup of coffee per day can help heart attack survivors by lowering their risk of death after a heart attack and can help prevent heart attacks or strokes in healthy people. 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. It may help to control appetite; may help to lower the risk of depression or boost alertness. Although 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.
The study aimed to determine whether the known protective effect of coffee also applies to individuals with different degrees of hypertension; and also examined the effects of green tea in the same population.
These findings may support the assertion that people with severe high blood pressure should avoid drinking excessive coffee. Since 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.
The study found that people with more frequent coffee consumption were more likely to be younger, current smokers, current drinkers, eat fewer vegetables, and have higher total cholesterol levels and lower systolic blood pressure (top number) regardless of the blood pressure category.
Green Tea Might be Better Than Coffee
The benefits of green tea may be explained by the presence of polyphenols, which are micronutrients with healthy antioxidant and anti-inflammatory properties found in plants. The researchers noted that polyphenols may be part of the reason only coffee consumption was associated with an increased risk of death in people with severe high blood pressure despite both green tea and coffee containing caffeine.
The research has several limitations like the coffee and tea consumption were self-reported. Blood pressure was measured at a single point, which did not account for changes over time. The observational nature of the study could not draw a direct cause-and-effect connection between coffee consumption and cardiovascular disease risk among people with severe high blood pressure.
Further research is needed 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.
Reference :
- Coffee and Green Tea Consumption and Cardiovascular Disease Mortality Among People With and Without Hypertension – (https:pubmed.ncbi.nlm.nih.gov/36542728/)
Source: Medindia
