Morning Potions
Unless you’re one of a lucky few, early mornings are difficult for everyone: Don’t expect much rational thinking from me before 10 am. But some beverages, known for long and from different corners of the world, seem to have a miraculous effect, making life easier when the bed keeps calling your name. Their effect seems to rely on a little and beautiful molecule called caffeine. What is it and why has it become sleepy men’s best friend?
Image by: Juan Cruz Landoni
Around 60 plant species in the world are known to contain caffeine. From an old Chinese guy smelling some tea leaves that fell into boiling water to hyperactive goats in Ethiopia whose master decided to try what they were eating, the stories about the discovery of the source of caffeine are diverse and quite amusing, but they all agree on one thing: Caffeine has been our friend for a really long time. But this is a science magazine and I am no historian. I’m a chemistry major, so let’s science the purine out of this:
Probably the word purine rings a bell to some of you: it is the family of molecules that includes Adenine and Guanine, the A and G from DNA and RNA. Caffeine is one of them. Their beautiful and similar structures can be admired below. This structural resemblance does not only allow us to classify it, but it is also thought to be the cause of the main effects of caffeine on your brain.
Image by: Juan Cruz Landoni
One of the best supported theories of how our brain measures how tired we are and turns us sleepy is the accumulation of adenosine. Adenosine is the Adenine we were talking about before, but with a sugar attached to it. Unsurprisingly, when adenosine gets three highly energetic phosphate groups attached to it, it becomes ATP (Adenosine triphosphate), the very famous energy currency of the cell.
But we’re getting away from our topic: How does caffeine make us feel less tired and turns us more alert? Today, when I woke up, my brain had very little levels of adenosine thanks to a lovely night of sleep. Some neurons in my brain have specific structures in their surface known as adenosine receptors, which allow them to recognize how much adenosine there is, and activate different processes accordingly. Adenosine slowly accumulated throughout the day, until a couple of hours ago, after a long day of work at the lab, my brain’s neurons identified the high levels and started making me feel tired. This is when caffeine came in handy: Drinking a delicious mate made the caffeine in its leaves get to my brain, and with its very similar structure to that of adenosine, filled up the receptors – without activating them. Caffeine tricked them into thinking the adenosine levels are low, I am well rested and it is a good idea to write this article at midnight on a Monday.
Image by: Juan Cruz Landoni
But why do plants make it in the first place? Evolution is simple: if a species starts producing something new, and that something new is harmful or a waste of resources, that species will die out; while if that something new is useful, the species will be favored and spread. Caffeine is found in species of plants from quite different families, which means its production was generated independently in each. So it has to be useful. But why would a plant want to produce something that makes their consumer feel more energetic?
It turns out it doesn’t. Plants seem to use caffeine as a pesticide, its high contents in the leaves and the small size of their common consumers (i.e insects) makes it cause serious adverse effects to them. And not only insects: Caffeine is toxic to birds, dogs and cats as well, so don’t share your tea with Rex. The exception to the insect rule seems to be the honeybee: Caffeine appears to increase their reward memory, something pollen producing plants can benefit a lot from.
Like everything, it can also be toxic to humans depending on the dose. Luckily for us all, though, a lethal dose would require drinking almost 100 cups of coffee in a single day, which I hope we all agree is impossible. So look forward to your morning espresso or your afternoon tea, I will serve myself one more mate and continue studying thanks to our very good friend.
Juan Cruz Landoni is a chemistry student and an undergraduate researcher in molecular neurology at the University of Helsinki. He's also a Millennium Youth Camp alumnus, a proud nerd, Ravenclaw and a part-time shooting star hunter.