How Does Caffeine Work in Our Body?

We all know caffeine is the key ingredient in coffee; just an 8oz cup of brewed coffee already contains about 95-165 mg of caffeine.

According to the video below, over 100,000 metric tons of caffeine are consumed annually around the world. It keeps us happy, awake, and focused even if we haven’t had a sufficient sleep. But how does this widely used drug do its trick?

Caffeine in the Human Body

In the human body, caffeine acts as a stimulant for the central nervous system (CNS). And now to answer the question, it keeps people awake by blocking one of the bodies’ key sleep-inducing molecules called adenosine.

Our body needs a continuous supply of energy which it gets by breaking down a high-energy molecule called ATP, and while it’s being broken, it liberates its chemical backbone which is adenosine.

The neurons in our brains have receptors flawlessly designed for this molecule. When adenosine comes in contact with these receptors, it activates a cascade of biochemical reactions causing neurons to fire more sluggishly. It also slows down the release of essential brain-signaling molecules, causing us to get sleepy.

Caffeine molecular structureThis is where caffeine comes in. It’s referred to as the adenosine receptor antagonist, which means it derails the process of slowing down the neurons by blocking adenosine receptors. Caffeine can do that because it has a similar molecular structure with adenosine that’s close enough to let caffeine wedge into the adenosine receptors but not close enough to activate them.

To sum it up, adenosine is responsible for the suppression of our neurons, while caffeine stops the inhibitor, waking us up.

Positive Effects of Caffeine

Caffeine can also boost positive feelings. In some neurons, adenosine receptors are connected to other receptors for dopamine. Dopamine, which is another molecule, promotes feelings of pleasure. When adenosine lands to one of these paired receptors, it can make it more difficult for dopamine to fit into its supposed position, which interrupts its work to lift up our mood. However, when caffeine takes the place of adenosine, it allows dopamine to do its job.

There is even evidence that the effects of caffeine on adenosine and dopamine can have long-term benefits such as the decrease of our chances to develop Parkinson’s disease, Alzheimer’s, and some types of cancers.

Caffeine can also help the body burn fat faster. Some sports organizations even believe that caffeine gives athletes an unfair advantage, and so they have placed limits on its consumption. In fact, from 1972 to 2004, Olympic athletes had to stay below a certain blood caffeine concentration to compete.

Coffee beatNegative Effects of Caffeine

Despite all that, there’s also a bad side to caffeine. One is that it can raise the heart rate and blood pressure levels which can lead to diarrhea and increased urination. It can also contribute to anxiety and insomnia.

Moreover, if our adenosine receptors are always loaded with caffeine, our bodies will manufacture more receptors so that even if there’s caffeine, adenosine can still perform its job of sending signals to the brain to power down. This is the reason why some people realize they need to consume more and more caffeine to feel as alert since the number of adenosine receptors to block has increased as well. It is also the same reason why withdrawing from coffee can be an unpleasant experience. Without the caffeine, adenosine can work overtime, which can cause headaches, tiredness, and depressed moods. However, after a few days, the extra adenosine receptors will disappear, and our bodies can readjust. We can then feel just as alert as ever even without consuming caffeine.