The Clever Chemistry of Caffeine

What happens in our bodies to keep us alive and well is nothing short of miraculous. The molecules of our food interact with our own cells and give us energy to get on with our day, to think clearly, to improve our coordination… the list feels endless.

Our course, when we say “tea”, we think “caffeine”. It is a common association now, and for good reasons. It is not the only one that is relevant to the way our body makes use of tea. But for now, that’s the one we will focus on. Caffeine is indeed an amazing molecule, and before we look into the specifics of caffeine in tea, we thought we would share interesting information about caffeine itself.

What is caffeine?

It is often said that caffeine is a natural stimulant. This is true, but did you know what we call chemicals that alter the perception, mood or behaviour because the affect the nervous system? Psychotropic drugs. So technically, caffeine is the most consumed psychotropic drug in the entire world! It is also one of the rare psychoactive drug that is legal and mostly unregulated.

Hand drawing of a caffeine molecule

Chemically specking, caffeine belong to the xanthine family. Two other xanthines can be found in tea, theophylline and theobromine. Caffeine was found independently in coffee in 1819 and in tea in 1827. It was then called theine and assumed it was different from caffeine. It was only in 1838 that chemists demonstrated that they are the exact same molecule.

It is still common to find content online that states that caffeine and theine are the same thing but do not act on the body in the same way. Well, this is a rather contradictory statement, isn’t it. It would be better to say that caffeine doesn’t have the exact same effect on the body if it is ingested through coffee or through tea. We will come back to that in another post.

How does caffeine work?

A psychoactive substance like caffeine changes the way the central nervous system, ie our brain and spinal cord, functions. But how can it do that?

The brain receives its information via molecules that attach themselves to the end of the nerve calls, in what is called a synapse. A synapse is a sort of pedestrian crossing for the body, where information is exchanged between nerves, or between a nerve and the bloodstream.

This information takes the shape of molecules and is highly regulated. Just like a key will fit in one lock and not another, a molecule has to find the right place to go in order for the information it represents to be acted upon.

Woman jumping in front of mountains

And that’s the very clever bit about caffeine. It can attach itself to a lock that was made for another molecule. That molecule is adenosine: it slowly builds up in the body during the day and induces drowsiness when it attach itself onto its synapse “lock”. But if instead caffeine is already there in the same lock, adenosine has nowhere to attach itself to. The result is... no drowsiness. That is the reason why caffeine maintains or improves alertness.

This effect is not permanent, which is why coffee drinkers talk about the coffee rush. However, too much caffeine present in the body over a long period of time, dependency symptoms might appear. Every person is different, but this is the basic of the caffeine biology.

But wait… Why caffeine?

It’s all very good to learn all this about caffeine, but surely Nature did not create this molecule just so that people all around the world would finally feel awake when they start their working day.

Far from it. In the natural world, caffeine is a natural pesticide. It can be found in high concentrations in the seedlings of the coffee plants and in the soil around it. This is the seedlings’ way to defend itself against insects that might want to take a bite, as well as against other seeds that might otherwise germinate too close and compete for resources. Later in the plant life, caffeine is mostly found in the leaves, again as a protection against hungry insects but maybe also against fungi.

Around thirty plants species are known to contain caffeine, including the coffee plants, the cocoa plant, and the camellia sinensis. And that will take us to looking more specifically at caffeine in tea... in another post!

(Photos by Darvaza Teas and Peter Conlan via Unsplash)

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