A recent study has demonstrated that compounds found in both green and black tea can relax blood vessels, explaining the antihypertensive properties of tea and potentially leading to new hypertension medications.
The research, published in Cellular Physiology and Biochemistry, identified two catechin-type flavonoid compounds in tea, namely epicatechin gallate and epigallocatechin-3-gallate.
These compounds activate a particular type of ion channel protein called KCNQ5, facilitating the diffusion of potassium ions out of cells, reducing cellular excitability.
KCNQ5 is located in the smooth muscle lining of blood vessels, and as predicted by the researchers, its activation by tea catechins resulted in blood vessel relaxation.
This prediction was confirmed by collaborators at the University of Copenhagen.
Professor Geoffrey Abbott, from the Department of Physiology and Biophysics at the University of California, Irvine’s School of Medicine, explained that these catechins bind to the voltage sensor of KCNQ5, allowing the channel to open more easily and earlier during the cellular excitation process.
Hypertension affects up to a third of the global adult population and is the leading modifiable risk factor for cardiovascular disease and premature death.
Thus, the discovery that catechins can lower blood pressure through KCNQ5 activation could contribute significantly to global public health.
Catechins, which are known to cross the blood-brain barrier, could also potentially be used to treat brain excitability disorders caused by KCNQ5 gene variants that impair channel function and lead to epileptic encephalopathy.
While the addition of milk to black tea was found to prevent the beneficial effects of tea on KCNQ5 activation in cells, the researchers are confident that the human stomach’s environment will separate the catechins from the milk’s proteins, allowing the catechins to exert their effects.
Furthermore, the study discovered that warming green tea to 35 degrees Celsius (95 degrees Fahrenheit) changes its chemical composition, enhancing its ability to activate KCNQ5.
These findings suggest that the consumption of tea, regardless of temperature, activates its antihypertensive properties.
This research was funded by the National Institutes of Health, National Institute of General Medical Sciences, the National Institute of Neurological Disorders and Stroke, the Lundbeck Foundation, and the Danmarks Frie Forskningsfond.
