Drinking tea helps lower blood pressure

IRVINE, Calif. — Tea has been going into people’s cups for around 4,000 years ago. Now, a recent study reveals it may be the secret ingredient for keeping your blood pressure in check. Researchers from the University of California-Irvine have discovered that tea contains compounds that help blood vessels relax.

Green tea, oolong, and black tea are the most popular teas which all come from the plant species Camellia sinensis. Currently, tea is one of the most popular beverages worldwide with the population consuming almost two billion cups daily.

The UC-Irvine team says these compounds stimulate proteins in the walls of blood vessels that control the flow of ions. This study which describes the ability of these compounds to lower blood pressure could help scientists develop new medications for hypertension.

2 compounds are key to removing free radicals

Dr. Geoffrey Abbott, a professor in the Department of Physiology and Biophysics at the UCI School of Medicine, discovered the compounds. The study showed a specific protein called KCNQ5 that regulates the flow of ions was activated by two plant compounds in tea that protect cells from free radical damage.

These compounds, epicatechin gallate and epigallocatechin-3-gallate, stimulate KCNQ5 proteins to move potassium ions out of the cells. The loss of potassium ions reduces the ability of the cells in blood vessels to become excited, causing them to relax. Researchers at the University of Copenhagen, who also worked on this study, demonstrated that the relaxation of blood vessels was stimulated by the catechins activation of the smooth muscle which lines the vessels.

“We found by using computer modeling and mutagenesis studies that specific catechins bind to the foot of the voltage sensor, which is the part of KCNQ5 that allows the channel to open in response to cellular excitation. This binding allows the channel to open much more easily and earlier in the cellular excitation process,” Abbott explains in a university release.

Structural model showing the tea flavonoid epicatechin gallate (blue/red) binding to the base of the voltage sensor (green) of KCNQ5, a type of potassium channel found in human blood vessels. (Credit: Geoff Abbott, UCI School of Medicine)

Hold the milk and serve your tea hot!

Researchers in Abbott’s lab found that the ion channels worked most efficiently under a direct application of pure black tea, rather than with the addition of milk.

“We don’t believe this means one needs to avoid milk when drinking tea to take advantage of the beneficial properties of tea,” Abbott says. “We are confident that the environment in the human stomach will separate the catechins from the proteins and other molecules in milk that would otherwise block catechins’ beneficial effects.”

Further studies suggested tea yields beneficial antihypertensive properties even with the addition of milk. Additional research also showed that green tea is more effective when warmed to 95 degrees Fahrenheit.

“Regardless of whether tea is consumed iced or hot, this temperature is achieved after tea is drunk, as the human body temperature is about 37 degrees Celsius,” Abbott concludes. “Thus, simply by drinking tea we activate its beneficial, antihypertensive properties.”

Globally, about 30 percent of adults suffer from hypertension, which is the main risk factor for cardiovascular disease as well as early death. With the addition of these findings on KCNQ5, researchers can now focus on the production of a more effective antihypertensive medication to improve the health of people worldwide.

These findings appear in the journal Cellular Physiology and Biochemistry.

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