Tea time for ion channels

It’s a chilly day here in Munich, the kind of day that begs for the warm embrace of a steaming cup of tea. Especially since today we celebrate Hot Tea Day. So, let’s wrap our hands around our favorite mugs and explore how certain compounds in tea can influence ion channels in our bodies.

Whether it’s robust black tea, aromatic oolong, or delicate green tea, each variety is a complex cocktail of chemicals, including caffeine, theanine, and polyphenols. Many of these chemicals are known to impact ion channel function.

Take caffeine, for example, a well-known stimulant found in coffee, tea, and many energy drinks. Although caffeine’s primary mechanism of action is antagonizing adenosine receptors in the brain, at higher doses, it also affects different types of ion channels, such as activating ryanodine receptors and inhibiting TRPA1, TREK1, Kir, and hERG channels. You shouldn’t, however, worry too much about hERG inhibition while enjoying a cup of pure green tea. Caffeine is a very weak hERG blocker (IC50 = 5mM), so it would require drinking liters of green tea to start seeing significant hERG inhibition by caffeine.

Another noteworthy compound in tea is L-theanine. This amino acid is renowned for its ability to promote relaxation without sleepiness. This calming counterpart to caffeine interacts with glutamate receptors and increases brain serotonin, dopamine, and GABA levels. This increase in GABA contributes to the relaxing, stress-reducing effects often attributed to tea.

Now, let’s take a look at polyphenols, a group of chemicals abundantly found in all types of tea. Polyphenols, including catechins, theaflavins, and tannins, are responsible for much of the flavor and color characteristics of tea. They are known for their antioxidant properties and are responsible for many of the health benefits attributed to tea consumption. Some of these benefits are directly related to the ability of polyphenols to modulate ion channels. For example, green tea catechins are known to potently sensitize the RYR1 receptor, while also inhibiting channels such as Kv1.5, hERG, and ASIC3. Additionally, they activate KCNQ5, a mechanism that contributes to the ability of green tea to reduce blood pressure.

Wrapping up, it’s pretty amazing how much good stuff is packed into our daily cup of tea. On this Hot Tea Day in Munich, as we enjoy our favorite flavors, it’s fascinating to think about how these tiny ingredients like caffeine, L-theanine, and polyphenols are quietly doing their thing, helping our bodies in their own special ways. From giving us a little energy boost to helping us chill out without feeling sleepy, and even looking after our hearts and blood pressure, tea is more than just a tasty drink. It’s a health booster in a mug. So, let’s enjoy our tea and feel good knowing it’s doing us a world of good with every sip.