It is estimated that one third of the world's population suffers from hypertension. Hypertension is also considered the most important risk factor for the development of heart disease. However, this condition is modifiable. This is why a lot of scientific research has been devoted to the study of remedies to keep blood pressure under control. Previous research had hypothesized a hypotensive action of both green and black tea. Thanks to a very recent scientific study it has been possible not only to demonstrate this property but also to understand its mechanism, and this could open the way to new treatments against hypertension. The research was published in the journal Cellular Physiology and Biochemistry by a team from the University of California, Irvine (Redford et al, Cell Physiol Biochem, 2021).
Hypotensive action of green and black tea
Green tea and black tea are valuable sources of antioxidant substances, such as epigallocatechin 3 gallate, or EGCG. These anti-radical substances have already been studied for their anti-cancer action but, as emerges from today's article, their effects are even more extensive and involve the control of blood pressure. The Californian researchers have in fact performed a series of studies, both in the laboratory using mass spectrometry techniques and through computer simulations, on cells placed in contact with green tea and black tea extracts. What emerged is that the tea extracts are able to bind to a particular protein, called KCNQ5. This protein allows the passage of potassium ions through the cell membrane and acts on the tone of smooth muscle by dilating blood vessels with a hypotensive effect. By binding to KCNQ5, green and black tea extracts increase its action by more than twenty times. This explains the hypotensive properties of the two types of tea.
Black tea and milk, does anything change?
But the researchers went even further. In fact, they were able to observe the action on blood pressure when milk is added to black tea, as often happens in various countries around the world. It has been observed that, in this case, the beneficial action of tea is inhibited. However, according to the researchers, the latter aspect has yet to be evaluated as the results are unclear. In fact, the research took place in the laboratory and does not say what could happen in the stomach, where catechins and milk could be separated. There are studies, in fact, which state that milk inactivates the action of the antioxidants in tea, while others observe that black tea and milk together still reduce blood pressure.