Since its discovery almost four thousand years ago in southeast Asia, tea has been widely consumed by all social classes all over the world. In fact, tea is the second most drunk beverage in the world, second only to water. However, 78 percent of the tea consumed worldwide is black and only about 20 percent is green tea. Tea and its health benefits have been studied for centuries and have been the goal of countless studies [1].
Now, a study published on the 6th of March 2021 from the School of Medicine at the University of California, analyzes the mechanisms which contribute to the positive effects of black and green tea on blood pressure. Scientists have found that antioxidants in tea open ion channels and can relax the muscles that line blood vessels.
Previous research in this area has shown that drinking green and black tea can lower blood pressure. It was already known that so-called catechins are involved but until now the exact way how the process works has not yet fully been understood.
The researchers around Dr. Geoffrey W. Abbott found that the catechins in green tea activate a particular type of potassium ion channel, called KCNQ5. They showed 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, explains senior study author Prof. Geoffrey Abbott.
In theory, this should make the muscle cells less “excitable” and therefore less likely to contract. They should instead relax, dilating the blood vessel and reducing blood pressure.
Tea, especially black tea is often drunk with milk. Although milk wrestled the beneficial effects of tea in laboratory experiments in the study, the researchers assume that this is not the case when a person drinks it. The team around Dr. Abbott believes that when you drink tea, you don't have to do without milk in order to get beneficial properties to use tea [3].
This assumption is confirmed by other studies that prove the antihypertensive effect of tea regardless of the addition of milk. Certain catechins reach their activated state after getting heated up to 35°C. This is not a problem either, because regardless of whether the tea is drunk cold or hot, due to the body temperature, they automatically develop their optimal effect.
Tea played a role in creating the world as we know it today. As the consumption of tea spread across the globe, it changed the areas it encountered. Tea gave birth to paper money, the opium wars, and Honk Kong, which triggered the Anglo-Dutch Wars and the American war of independence. With more than 2 billion people currently consuming tea daily in one form or another, it is still playing a significant role in society [2].
Though people have only recently started studying the science behind tea’s perceived health benefits, there is a growing pool of evidence that drinking tea, especially green tea, can help with cardiovascular health and can inhibit carcinogenesis. The researchers involved are concluding, that the discovery in this study could guide the design of more effective antihypertensive drugs, which then could potentially improve the health of millions of people around the world.
Sources:
[2] George van Driem, The Tale of Tea, Brill 2019
[3] International Journal of Experimental Cellular Physiology, Biochemistry, and Pharmacology