Why do we like coffee so much? For its taste? Sure. For its color? Maybe. Because it is a cool drink to have? Probably. But one of the biggest reasons is usually because of the effect it has on us – the molecular sympathy between human and coffee biochemistry. Caffeine, and by extension, coffee gets us awake and alert, helping us feel energetic, and as many of us put it ‘get our brains to start working’.
But ever wondered how coffee manages to do that? What happens to the caffeine once it has done its part in kicking you awake?
What does caffeine do?
Our neurons are constantly working, firing out pulses. As part of this process, a neuromodulator called adenosine is produced. This adenosine bonds to the specific adenosine receptors to have an effect on the body. When the amount of the adenosine molecules increases in your blood, it signals your brain to slow down, dilate your blood vessels, tone things down a notch, and you end up feeling sleepy, drowsy, seeking rest.
Now, here is the interesting part. The molecular structure of caffeine is very, very similar to that of adenosine – the same double nitrogen ring structure. Due to this unique property, the adenosine receptors can also function as caffeine receptors. Let me give you an analogy. Imagine a jigsaw puzzle, where every piece is unique. Now, every piece would fit to another unique piece. But sometimes, two pieces are so similarly shaped that both can fit perfectly fine with another piece. Makes sense?
So, the protein with which adenosine can bind, is also the same protein with which caffeine can bind because they both have the same structure. Now, you’ve just had a cup of coffee. The caffeine from the coffee is competing with the adenosine to bind to the receptors. Now, caffeine has bound to the receptors, so adenosine is not able to. Like adenosine, caffeine can bind to the receptor proteins, but caffeine cannot activate the protein and trigger further action of the protein the body. As a result, you feel and stay awake and alert.
This is how caffeine functions.
What is caffeine?
Caffeine in its pure form is a white, bitter, odorless powder. It is a type of organic compound class called purine alkaloids. Besides coffee, caffeine is commonly present in many other plant-origin beverages like tea, cocoa, yerba mate, guarana, etc. While caffeine does work as a pesticide for some pests, it tends to sharpen the memory of some others. This is a chief reason why the return rate of insects to plants containing caffeine in its parts is exceedingly high. For instance, bees that have consumed caffeine are usually three times more likely to remember the scent of a flower, which makes them return to the plant more often, there by ensuring pollination and reproductive success for the plant.
What is the effect of caffeine on the human body?
A very general answer to this question would be – a mild diuretic effect and a mild stimulant especially for the nervous, circulatory, and the respiratory systems.
But to understand the effect caffeine has on the human body better, one needs to understand how caffeine is metabolized in our bodies. Once caffeine absorbs into the digestive tract, it will generally remain in the system for roughly four to six hours. The liver breaks caffeine down into three key compounds in varying quantities:
The main breakdown compound of caffeine is paraxanthine, while theobromine is produced in lesser quantities, and theophylline is produced in even lesser quantities.
Paraxanthine boosts the process of fat breakdown in the body.
Theobromine is responsible for causing the dilating of the blood vessels and increasing urine production.
The tiny amount of theophylline that gets produced relaxes the smooth muscles in the body. Smooth muscles are a type of muscles that cover the organs in our body, especially those in the digestive, respiratory, and circulatory systems. Thus, theophylline causes quickening of the heart rate, increasing the blood flow to muscles while reducing the flow to skin and other organs. It also causes the liver to release glycogen.
One notable property of caffeine is that it is completely water soluble. Due to this, it can easily move through the body and can even break past the blood-brain barrier and reach the brain.
In the brain, caffeine increases the production of some important compounds –
- Epinephrine (Adrenalin), a hormone
- Dopamine, a neurotransmitter
- Serotonin, another neurotransmitter
- Acetylcholine, yet another neurotransmitter
All these four compounds induce a change of mood in our bodies. Ever felt happier, more active and energetic, and ready to take on the world after drinking coffee? Now you know where that is coming from.
Caffeine increases the breathing rate and the heart rate for the short term, thus bringing about a release of a small amount of energy.
Does caffeine have any health benefits?
There are some health benefits linked to caffeine, found in some studies:
- Increase rate of metabolism
- Improved muscle strength
- Decreases risk of diabetes
- Decreases risk of cancer
- Decreases risk of heart diseases
Is caffeine addictive?
NO. Studies have shown that caffeine is not addictive. Caffeine does not activate the usual reward circuits in the brain responsible for forming a dependency with a compound. Hence, it is not usually addictive. However, consumption in moderation is important. Over-consumption of caffeine can cause a mild physical dependence. If you do develop this physical dependence, you will also develop withdrawal symptoms if you do not get your caffeine intake sometime. Common caffeine withdrawal symptoms include headaches, fatigue, irritability, anxiety, but the symptoms would likely subside in a few days. Consult a doctor if you have a dependence and are trying to get over it. I would suggest giving up coffee gradually if you are trying to kick the habit, instead of just giving it up altogether one day. However, listen to what your doctor says.
The caffeine metabolites eventually make their way to our kidneys from where they are thrown out of the body. If you ever wondered why you reek of coffee sometimes, now you know. It also your body’s way of telling you to drink more water so the caffeine metabolites can be washed out from your body. So, if you are consuming caffeine in any form, drink plenty of water to ensure a smooth movement of caffeine and its by-products from your body.
Which beans have more caffeine – green coffee beans or roasted coffee beans?
Roasted coffee beans have a few times more caffeine than green beans. Roasting causes chemical changes in the coffee beans. It also leads to evaporation of moisture, concentrating the compounds present in the coffee beans. A small amount of caffeine also gets lost during the process of roasting the coffee beans.
Even in roasted coffee beans, the light roasted coffee beans will have more caffeine than dark roasted coffee beans.
Generally speaking, Robusta coffee has double the amount of caffeine that Arabica coffee. This is also one of the reasons why Robusta is more study, less sensitive to pests, and lacks the flavor nuances of Arabica coffee due to the bitter taste of caffeine.
Now you have a better picture of what happens to caffeine in your body and its good & bad effects on the human body. Drink coffee mindfully and avoid over-consumption. Listen to your body and live a happy, healthy life!