Written by Jahnavi Sarma |Updated : March 10, 2021 11:11 AM IST
Tea lovers will agree that a cup of their favourite beverage gives them a boost, mental as well as physical. And, we have been hearing for a long time now, that some teas come with immense health benefits. Now a new study titled 'KCNQ5 potassium channel activation underlies vasodilation by tea' from the University of California, Irvine, says that certain compounds in both green and black tea have the ability to relax the blood vessels by activating the ion channel proteins in the blood vessel wall. Researchers say this discovery helps explain the anti-hypertensive properties of tea and they are hopeful that this finding can lead to the design of new blood pressure-lowering medications. Cellular Physiology and Biochemistry published this study. Hypertension or high blood pressure is a major global worry today and, according to sources, as many as one third of the world's adult population have hypertension. In fact, this condition is the number one modifiable risk factor for global cardiovascular disease and premature mortality. Hence, new approaches to treating hypertension have enormous potential to improve global public health.
According to researchers of this study, two catechin-type flavonoid compounds (epicatechin gallate and epigallocatechin-3-gallate) found in tea, can each activate a specific type of ion channel protein named KCNQ5. This allows potassium ions to diffuse out of cells to reduce cellular excitability. As KCNQ5 is found in the smooth muscle that lines blood vessels, it is a given that its activation by tea catechins can relax blood vessels. For the purpose of the study, researchers analysed computer modeling and mutagenesis studies to come to the conclusion 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.
Earlier studies had demonstrated that consumption of green tea or black tea can reduce high blood pressure by a small but consistent amount, and catechins were previously found to contribute to this property. Identification of KCNQ5 as a novel target for the hypertensive properties of tea catechins may facilitate medicinal chemistry optimization for improved potency or efficacy.
Any caffeinated teas (green, oolong, and black) can help you control your hypertension. But if you mix black tea with milk, as is the practice in many countries, it will not help. The researchers of the above-mentioned study found that when black tea was directly applied to cells containing the KCNQ5 channel, the addition of milk prevented the beneficial KCNQ5-activating effects of tea. But researchers are quick to point out that this does not mean that you need to avoid milk when drinking tea to take advantage of the beneficial properties of tea. They believe that the environment in the human stomach will separate the catechins from the proteins and other molecules in milk that would otherwise block the catechins' beneficial effects.
Many studies show that you can get the anti-hypertensive benefits of tea regardless of milk co-consumption. Researchers found, using mass spectrometry, that warming green tea to 35 degrees Celsius alters its chemical composition in a way that renders it more effective at activating KCNQ5. In fact, they say that regardless of whether tea is consumed iced or hot, this temperature is achieved after tea is drunk, as human body temperature is about 37 degrees Celsius. Thus, simply by drinking tea, you can activate its beneficial, anti-hypertensive properties and keep your high blood pressure under medically acceptable limits.
In addition to its role in controlling high blood pressure, KCNQ5 is expressed in various parts of the brain, where it regulates electrical activity and signaling between neurons. Pathogenic KCNQ5 gene variants exist that impair its channel function and in doing so cause epileptic encephalopathy, a developmental disorder that is severely debilitating and causes frequent seizures. Because catechins can cross the blood-brain barrier, discovery of their ability to activate KCNQ5 may suggest a future mechanism to fix broken KCNQ5 channels to ameliorate brain excitability disorders stemming from their dysfunction.
(With inputs from Agencies)
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