Around 33 percent of all Americans have high blood pressure, medically termed hypertension, according to the United States Department of Agriculture. Hypertension raises your risk of heart disease and stroke -- the major causes of death in the United States. Drinking tea will not instantly lower your blood pressure, no matter which tea you choose. Some teas temporarily raise, rather than lower, your blood pressure, while others could help lower your blood pressure over time.
Hibiscus Tea
Tea made from the leaves of the hibiscus plant can lower blood pressure in people with mild hypertension over a six-week period, an Agricultural Research Service study showed. People who drank three cups of hibiscus tea daily experienced a drop of 7.2 millimeters of mercury, or mm/Hg, in their systolic blood pressure. This is the top number measured on blood pressure readings. The systolic reading measures the force exerted by the heart against the blood pressure when the heart contracts. People taking placebo had a drop of 1.3 mm/Hg. The 30 people with the highest blood pressure experienced the largest drop in systolic pressure, 13.2 mm/Hg on average, while diastolic blood pressure fell 6.2 mm/Hg. these results are promising but not instantaneous.
Green and Oolong Tea
Black tea, green tea and oolong tea all come from the Camellia sinensis plant. These "true" teas are processed differently, with black tea leaves being fully fermented while green and oolong tea being less fermented. In China, green tea is more popular than the black tea more Americans drink. A Chinese study reported in the July 2004 issue of the "Archives of Internal Medicine" found that tea drinkers reduced their risk of developing hypertension by 46 to 65 percent, depending on whether they drank 4 oz. or 20 oz. per day. However, this study was conducted over a one-year time period and did not show an instant reduction in blood pressure.
Caffeine Effects
All teas from the Camellia sinesus plant contain caffeine, with black tea containing the most. Caffeine causes a short-term rise in blood pressure of 3 to 14 mm/Hg systolic and 4 to 13 mm/Hg diastolic, according to MayoClinic.com. Not everyone who drinks caffeine-containing beverages experiences this effect, so check your blood pressure before and after consuming caffeinated tea to see if it has any effect on your blood pressure. If you have high blood pressure, limit your caffeine intake to 200 mg a day, or around two 12-oz. cups of brewed coffee, MayoClinic.com suggests.
Considerations
Don't drink tea expecting immediate results on your blood pressure. If you drink black tea, the most popularly consumed tea in the United States, your blood pressure may rise, rather than fall. While green tea and hibisicus teas may lower your blood pressure over time, to lower your blood pressure quickly, you would need medication prescribed by your physician.
References
- Agricultural Research Service; Study Shows Consuming Hibiscus Tea Lowers Blood Pressure; Rosalie Bliss; November 2008
- "Archives of Internal Medicine"; The Protective Effect of Habitual Tea Consumption on Hypertension; Yi-Ching Yang, M.D., et al.; July 2004
- MayoClinic.com; Caffeine: How Does It Affect Blood Pressure?; Sheldon G. Sheps, M.D.; November 2009
- University of Maryland Medical Center; Green Tea; September 2010
