Caffeine and Its Effect on the Human Body

Caffeine is a substance we have all heard about and is found in many forms, such as coffee, tea, and energy drinks. Most of us might have also heard about the various effects, both positive and negative, that it can have on the human body. But what is caffeine really? And what effects does it actually have?

What is Caffeine?

Caffeine is the most commonly found stimulant, and can also act as an analgesic. It is a molecule that can be found naturally in more than 60 different plant species and can also be made artificially. It is present in different parts of the plant, such as the leaves, seeds (for example, coffee beans, which are the most commonly found source of caffeine), and fruit. The amount of caffeine depends significantly on the type of plant being used and how it is made. 

How Does It Get Absorbed in the Body?

After intaking caffeine, it is quickly absorbed by the body via the bloodstream. This is due to caffeine’s high solubility in both water and organic solvents (meaning it has both hydrophilic and hydrophobic qualities). Some 80% of caffeine is absorbed through the gastrointestinal tract, while the remaining 20% is absorbed through the stomach. 

Caffeine is readily absorbed into the body and reaches peak concentration in our bodies roughly an hour after intake. Yet this differs from person to person and the way caffeine is consumed. For example, caffeine from tea and coffee absorbs faster compared to soft drinks. 

Once absorbed, most of the caffeine molecules are distributed to different organs and body tissues. The aforementioned hydrophilic properties entail that caffeine can be distributed into intracellular tissue water (water within tissue cells).

Additionally, caffeine can also pass through all membranes in the body, one of which is the blood-brain barrier. This is why high concentrations of caffeine can be found in the brain, since caffeine blocks adenosine receptors (others include inhibition of the phosphodiesterase enzyme and release of calcium from storages), which are located in different parts of the brain. Adenosine receptors have many roles in the body, such as regulating movement, cardiac contractility, and sleep, which is why when caffeine blocks these receptors, it can have a noticeable effect on your body.  

Effects of Caffeine

When consumed in moderate amounts, caffeine does not solely have a negative effect on our bodies, in fact there are some effects that can actually be useful. One such effect is energy levels, because of how it blocks adenosine receptors, which are responsible for promoting sleep, added by the fact it affects your central nervous system as a stimulant.

Furthermore, current research shows that caffeine has an effect on reducing the effects of two of the most common neurodegenerative diseases: Alzheimer's and Parkinson’s. Caffeine is not a cure, though it has been shown to have neuroprotective effects, which can slow the onset of these diseases. On the other hand, this is ongoing research, thus the mechanism of how caffeine does this is hypothesised, not proven. 

When consumed in excess amounts, caffeine can lead to undesirable side effects, especially during caffeine withdrawals. Because of the effect caffeine has on the central nervous system, it can have effects such as an temporary increase in blood pressure, confusion due to overstimulation, and heartburn due to the acidity of certain types. 

Most negative effects occur due to overdose, but can also be a symptom of caffeine withdrawal, since the effects are particularly prominent during caffeine withdrawal, since your body has already gotten used to the effects of it.