We’ve all been there—you hear someone say they simply can’t live without coffee. But what is it about this beloved beverage that can actually change your mood? In this article, we’ll explore a few key compounds in coffee that can explain why it has such a noticeable effect on how you feel. 

 

Coffee is one of the most popular drinks in the world—if not the most popular. Over the years, many research papers have explored coffee and its effects on our bodies and minds. According to a 2023 study by Makiso and colleagues, coffee contains a variety of compounds, including caffeine, chlorogenic acid, melanoidins, diterpenes, and trigonelline.

Different types of coffee, like green coffee, also contain unique compounds such as lignans and anthocyanins.

Now, you might be thinking: “What are all these compounds, and why should I care?” Don’t worry—I’ll break down what each of these does and how they can influence your mood and well-being.

 

Before diving into how coffee affects your mood, it’s important to understand which types of molecules are present in coffee beans. These molecules are what give coffee its unique flavor, aroma, and stimulating effects—and they’re the reason a cup of coffee can actually change the way you feel.

 

Coffee beans are packed with a variety of components, including lipids (fats), carbohydrates, and phenolic acids. Each of these plays a role not just in the taste and aroma of coffee, but also in how it can affect your mood. In the sections below, I’ll highlight examples from each category and explain how they can influence the way you feel after a cup of coffee.

 

Alkaloids

Alkaloids are a group of compounds made up of carbon, hydrogen, and nitrogen. These compounds are naturally produced by plants, often as a defense mechanism. The most famous alkaloid in coffee is caffeine, which is well-known for its stimulating effects on the brain and body.

Chemical structure of caffeine.  It is one example of alkaloids since it contains nitrogen and it is produced by plants.

 

Caffeine is a natural stimulant. When you consume it, it activates your nervous system, which can make you feel more alert, focused, and even a bit excited. One of caffeine’s key effects is its ability to reduce feelings of tiredness, giving you that much-needed energy boost.

Your brain has special receptors called adenosine receptors, which normally help regulate your sleepiness and relaxation. Caffeine can bind to these receptors, blocking their normal function. The two types of adenosine receptors most commonly discussed in research are A1 receptors and A2A receptors.

 

Among these, the A2A receptor is thought to be the key player behind the alertness and excitement you feel after a cup of coffee. A little science to keep in mind next time you enjoy your favorite brew!

 

When caffeine binds to these receptors, it prevents them from being activated—think of it like trying to squeeze into a shoe that’s just a bit too tight.

 

The neurons that contain these receptors don’t function normally on their own. Adenosine receptors are neuromodulators, which means they help control the activity of other neurons—especially the ones that excite your brain. Normally, when you start feeling tired, the A2A receptors become active and slow down these excitatory neurons.

But when you drink coffee, caffeine steps in and blocks these receptors. Imagine putting gum on a key so it can’t open a door—this is basically what caffeine does to the receptors. With the receptors blocked, excitatory neurons stay active, leading to more dopamine in your brain. The result? You feel more alert, awake, and ready to take on the day.

Caffeine doesn’t stay caffeine forever in your body—it undergoes further chemical changes. Most of it is broken down into a compound called paraxanthine, while smaller amounts are converted into theobromine and theophylline. These metabolites also have mild stimulating effects, which can contribute to the alert and energized feeling you get after drinking coffee.

 

Paraxanthine, the main breakdown product of caffeine, has been shown to boost alertness. Studies also suggest it can improve reaction time, reduce cognitive fatigue, and enhance brain function, especially before physical exercise. In other words, it’s one of the compounds that helps keep your mind sharp and focused after a cup of coffee.

 

Theobromine, on the other hand, doesn’t seem to have a major impact on mood or alertness, according to two separate studies. Its main effect appeared to be a slight decrease in calmness among participants. That said, some studies noted a small improvement in mood when caffeine and theobromine were consumed together, but the effect wasn’t statistically significant.

 

The same goes for theophylline. In a study by Fitzpatrick et al. (1992), theophylline did not have a significant impact on mood. More recent research by Scurek and Brat (2024) also remains inconclusive, leaving the effects of theophylline on mood still unclear.

 

Alright, we’ve covered caffeine and its metabolites—now let’s take a look at other compounds in coffee that can influence your mood. While caffeine gets most of the attention, these molecules also play an important role in how coffee makes you feel.

 

Polyphenols and L-theanine

 

These compounds are present while coffee is being prepared. A specifc example of polyphenol present in coffe is chlorogneic acid. It is estimated taht daily coffe drinker is taking in 0.5 – 1 gram of this compound per day.

 

L-theanine is an atypical amino acid, meaning it doesn’t build proteins like most amino acids do. A study by Owen et al. (2013) looked at participants who consumed caffeine alone versus those who consumed caffeine with L-theanine. The results showed that participants who had both compounds experienced better mood and improved cognitive performance. This suggests that L-theanine may play a role in the mood changes people often feel after drinking coffee.

 

Polyphenols have been shown to interact with several neurotransmitters in the brain, leading to increased release of dopamine, serotonin, and norepinephrine. This activity contributes to the alertness and improved mood you often feel after a cup of coffee.

 

Interestingly, polyphenols in coffee play such a significant role in brain function that they are even studied as part of depression management. I’ll dive into that in another blog, explaining how it works. For now, though, let’s stick to our current topic: how coffee affects your mood and alertness.

 

Other compounds 

 

Coffee also contains other interesting compounds, such as catechol, pyrogallol, and eicosenoyl-5-hydroxytryptamide. These compounds can influence brain function by increasing the release of dopamine and calcium, which in turn can make you feel more alert, energized, and generally excited.

 

It’s worth noting that most of the physiological effects of coffee come from caffeine. This isn’t to discount the other compounds, since we now know they also have properties that can influence mood. But when it comes to that stimulating, mood-lifting effect you feel after a cup of coffee, you can mostly thank caffeine for the boost. 🙂