Epidemiological investigations have shown that tea consumption may exert a lowering effect on blood pressure. A survey of adults in China that average rate of hypertension in the group who drank tea as a habit was lower than that in the group who did not.
A clinical investigations on patients with hypertension revealed that a 10 g daily intake of green tea for half a year resulted in reduction of the blood pressure by 20-30%.Oral administration of tea polyphenols also yielded a decrease of blood pressure in patients, a number of studies also revealed the blood pressure decreasing effects of tea in experimental animal models.
The reported active substance include tea extracts, polyphenols and tea tannin.
In addition, theanine, the amino acid component of tea, was found to be effective in decreasing the blood pressure of spontaneous hypertensive rates.
Caffeine may exert a variable effect on blood pressure. Intravenous administration of caffeine may cause an initial fall in blood pressure and then a secondary rise.
So, caffeine should be taken into account if whole tea preparation instead of tea component is used in studying the effect on blood pressure.
Tea Effects on Blood Pressure
