Drinking green and black tea lowers blood pressure

A new study from the University of California, Irvine shows that compounds in green and black tea relax blood vessels by activating ion channel proteins in the blood vessel wall. This discovery helps explain the antihypertensive properties of tea and could lead to the design of new antihypertensive drugs.

Posted in Cell physiology and biochemistry, the discovery was made by the laboratory of Geoffrey Abbott, PhD, professor in the Department of Physiology and Biophysics at the UCI School of Medicine.

Research results revealed that two catechin-like flavonoid compounds (catechins are a type of natural phenol and antioxidant) found in tea, each activate a specific type of ion channel protein called KCNQ5, which allows ions potassium to diffuse out of cells to reduce cell excitability. Since KCNQ5 is found in the smooth muscle that lines blood vessels, its activation by tea catechins has also been predicted to relax blood vessels, thereby lowering blood pressure.

While previous studies have shown that drinking green or black tea can lower blood pressure by a small but consistent amount, identifying KCNQ5 as a new target for the hypertensive properties of tea catechins may facilitate the creation of new ones. drugs or dietetic methods to control hypertension. .

Tea has been produced and consumed for over 4,000 years and over 2 billion cups of tea are currently drunk globally every day, just behind water in terms of the volume consumed by people around the world. The three commonly consumed caffeinated teas (green, oolong, and black) are all produced from the leaves of the evergreen species. Camellia sinensis, differences resulting from different degrees of fermentation during tea production.

Black tea is usually mixed with milk before it is consumed in many countries. The researchers in the present study found that when black tea was applied directly to cells containing the KCNQ5 channel, the addition of milk prevented the beneficial effects of tea in activating KCNQ5. However, according to Abbott, “We don’t think that means avoiding milk while drinking tea to experience the beneficial properties of tea. We are convinced that the environment of the human stomach will separate catechins from proteins and other molecules in milk which would otherwise block the beneficial effects of catechins.

This hypothesis is confirmed by other studies showing the antihypertensive benefits of tea, whether consumed with milk. The team also found, using mass spectrometry, that warming green tea to 35 degrees Celsius altered its chemical makeup in a way that made it more effective at activating KCNQ5.

“Whether the tea is consumed iced or hot, this temperature is reached after the tea is consumed because the human body temperature is around 37 degrees Celsius,” Abbott explained. “So, just by drinking tea, we activate its beneficial antihypertensive properties.”

Source: UCI School of Medicine