Drinking black tea may reduce blood pressure variation at night, according to a new study.
Black tea is made from the dried leaves of Camellia sinensis, a shrub native to southeastern Asia. Green tea, black tea and oolong tea all come from the same plant. Black tea is a traditional beverage in Britain. The quality of tea depends on the age of the tea leaves.
Black tea is a source of caffeine, which stimulates the heart and central nervous system, relaxes smooth muscle in the lungs and promotes urination. One cup of tea contains about 50 milligrams of caffeine, depending on the strength and size of the cup, while coffee contains 65-175 milligrams of caffeine per cup. Tea also contains vitamins, a compound called tannin, and antioxidants called polyphenols.
In a new study, researchers randomly assigned 11 individuals with systolic blood pressure of 115-150 millimeters of mercury to drink three cups daily of black tea or a caffeine-containing flavonoid-free control drink for six months to evaluate the potential effects of black tea on blood pressure variation. Blood pressure variation measurements were collected throughout the study.
The researchers found that individuals in the tea group had significantly lower blood pressure variation at night by about 10 percent, but not during the day, when compared to the control group. The authors noted that these effects were present on day one of the study and were maintained at each check point throughout the study.
The authors concluded that other components of black tea, not just caffeine, may beneficially lower blood pressure variability at night.
In addition to black tea, several studies suggest that green tea may have an effect on blood pressure. Furthermore, multiple human trials have reported small reductions in blood pressure with intake of omega-3 fatty acids. DHA may have greater benefits than EPA. However, high daily intakes of omega-3 fatty acids may be necessary to obtain clinically relevant effects, and at high dose levels, there is an increased risk of bleeding. Therefore, a qualified healthcare provider should be consulted prior to starting treatment with supplements.
For more information on integrative therapies for high blood pressure, please visit Natural Standard's Comparative Effectiveness Database.
For more information about black tea, please visit Natural Standard's Foods, Herbs & Supplements Database.
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