Caffeine metabolism – How it relates to energy drinks

Caffeine metabolism

Caffeine is the most commonly consumed psycho-stimulant in the world. It’s mainly found in the beans, leaves, and fruits of over 60 plants.

The primary sources of caffeine are coffee beans and tea leaves.

However, caffeine is also found in a few other sources such as guarana, guayusa, and kola nut. Caffeine is primarily consumed in drinks such as coffee, tea, soda and energy drinks.

The US FDA generally recognizes caffeine as safe when consumed in no more than 400mg a day.

For comparison, a regular cup of coffee contains around 100mg of caffeine, so you could safely consume a few cups a day. The average energy drink typically contains around 80mg of caffeine, although, there is a lot of variation from brand to brand.

So, how does caffeine metabolism relate to energy drinks?

Well, all energy drinks contain caffeine in different quantities, so it’s important to know just how much you’re drinking and how it affects your body.

Caffeine metabolism

The way our body breaks down caffeine is pretty interesting.

Within just 45 minutes of ingesting caffeine, it is fully absorbed into our bloodstream and tissues. It is during this period we tend to feel the strongest effects of caffeine.

But, that also depends on your genetic makeup.

Some people might experience the peak effects earlier, while others a little later.

Caffeine is distributed throughout our body with the help of bodily fluids such as blood and saliva. Once it reaches the liver, it’s broken down into smaller fragments.

This is all thanks to a special enzyme that is only found in our liver.

How long does it take to get the caffeine out of your system?

Caffeine has a half-life of four to five hours.

This is the amount of time it takes for your liver to flush out half of the caffeine that’s in your body. Certain factors can affect the time it takes though.

What determines caffeine metabolism?

For starters, it’s your unique genetic makeup.

Some people are naturally more tolerant to caffeine than others. People with high tolerance levels for caffeine tend to metabolize it at a faster pace. Whereas those that do not metabolize it at a slower pace.

Besides that, your gender also plays an important role in caffeine metabolism.

Caffeine metabolism can be affected by Gender
Your gender plays a role in the rate that your body breaks down caffeine.

This is especially true in pregnant women, as their caffeine metabolic rate is greatly reduced during pregnancy.

Boys, in general, have a greater metabolic reaction to caffeine. This simply means that men break down caffeine at a faster rate compared than women.

Other than that, if you are suffering from liver disease, that can also affect your body’s ability to break down caffeine.

Your liver is mainly responsible for caffeine metabolism.

Liver disease reduces your body’s ability to get rid of caffeine from your system.

The more severe the disease, the slower it is for your body to get rid of caffeine.

If you’re a smoker, this could also affect how long it takes for your body to get rid of caffeine.

There have been studies showing that smoking can help to quicken the process. Smoking stimulates the enzymes responsible for caffeine metabolism, which speeds up your body’s rate of breaking down caffeine.

Certain medications can also affect the way your body metabolizes caffeine and potentially cause some serious side effects.

If you’re taking any kind of medication, I would strongly suggest you consult your doctor to see if you can ingest caffeine or not.

What’s the difference between energy drinks and coffee?

Energy drinks and coffee are similar because they both contain caffeine.

However, they are each different from one another.

This is fairly obvious, but coffee is different from energy drinks because it’s an all-natural beverage. Energy drinks on the other hand usually include a bunch of ingredients that coffee does not contain. Things like B group vitamins, taurine, ginseng and guarana are fairly commonly included in energy drink ingredients.

Coffee has been around for many years, whereas energy drinks were only just introduced a few decades ago.

There has been tons of research on the long term effects of coffee over the last couple of decades. Energy drinks on the other hand are the new kids on the block and haven’t been studied for nearly as long.

However, just to be clear, the caffeine in coffee affects the human body in exactly the same way as the caffeine in energy drinks.

Coffee contain caffeine caffeine metabolism
Coffee has been around since the 15th century.

The main difference are the ingredients in each of them

Coffee mainly contains caffeine and sugar or creamer, depending on your preference. Energy drinks on the other hand contain a wide variety of ingredients that come pre-packaged and out of your control.

Besides sugar and caffeine, most energy drinks also contain ingredients such as B vitamins, taurine, ginseng, guarana, preservatives, citric acid, and more.

Energy drinks have a standardized caffeine content per serve. Caffeine in coffee on the other hand varies depending on the brewing method, the type of coffee beans and roasting methods used and so on.

Energy drinks usually have a label on the back of the can that states the caffeine content. With coffee, you’re usually guessing the approximate amount of caffeine in each serving.

Are there any benefits to energy drinks?

Yes! Drinking energy drinks has many benefits:

  • More energy

    This seems obvious, but most people drink energy drinks just to feel more energetic than they did before.

    How much of an effect it’s going to have on your energy levels depends mainly on the strength of the energy drink that you’re drinking and on your unique genetic makeup.

    If you’re curious about which energy drinks are the strongest, check out my other article.

    Girl energetic stretching arm
    Energy drinks can give you the energy boost you need.
  • Increased brain function

    There have been numerous studies that show that energy drinks can help to improve your memory, focus and response time, while also decreasing mental weakness.

    In fact, drinking a can of Red Bull can help improve your precision, speed and recall.

  • Additional Ingredients

    Other than caffeine, energy drinks often contain other ingredients such as taurine, vitamin B’s, and ginseng. All of these ingredients can improve an energy drinks effects and your good for your health.

  • Convenience

    Unlike coffee or tea, energy drinks don’t have to be brewed. They come in a can and are ready to drink.

  • Fast caffeine delivery

    Energy drinks are often served chilled. 

    Because of this, you can drink it much quicker than coffee which is usually served piping hot. Being able to drink at a faster pace helps to get more caffeine into your bloodstream quicker.

  • Standardized caffeine content

    Monster Khaos is said to contain caffeine
    Energy drinks have their caffeine content stated on the can.

    If you were to compare coffee and energy drinks, it’s easier to determine how much caffeine is in an energy drink.

    On every can of energy drink, there is a label indicating the caffeine content. It’s standardized, by flavor and brand of energy drink.

    For coffee, it’s hard to determine how much caffeine is in each serve. Depending on the brewing method, the type of coffee beans and roasting method used, the caffeine content in coffee can vary significantly.

  • A variety of flavors

    Energy drinks come in a wide variety of flavors. For those of you who don’t like the taste of coffee or tea but still want a caffeine boost, it’s pretty likely that you’ll find a taste that you like in an energy drink because there are so many different flavors to choose from.

  • Zero calorie versions

    For those of us who want to keep an eye on our calorie intake, but still want a caffeine boost, black coffee is usually our go-to drink in the coffee category.

    However, if you’re like me, you probably don’t particularly like the taste of black coffee, no sugar.

    If that’s the case, zero-cal energy drinks might be the solution.

    Nowadays, energy drinks often have a zero calorie version that delivers the caffeine to you without the calories, but with a much nicer taste than black coffee.

What are the effects of energy drinks?

As good as they sound, energy drinks can cause some side effects if you drink them in excess.

Here are the known side effects of energy drinks:

Effects of energy drink on the heart

Energy drinks cause your heart rate to increase. This is a common side effect of drinking energy drinks.

As we all know, many energy drinks contain tons of caffeine.

In general, caffeine is not bad for you. However in large doses it can cause problems with your heart.

Just minutes after consuming an energy drink, you’ll probably notice that your heart rate starts to rise. This is mainly because of the caffeine.

Energy drinks that contain a large amount of caffeine, like Bang energy, cause your blood pressure to increase. This is because your heart starts to pump blood throughout your body at a faster rate.

The back of a Bang energy drink and nutritional facts
Bang energy drink contains 300mg of caffeine in one serving which is an astounding amount compared to most of the leading energy drink brands.

Because caffeine gets transported around your body at a faster rate, you may think that it’s a good thing because you get a quicker energy boost.

But in reality, it’s the other way around.

There have been studies that show in addition to increasing your heart rate, energy drinks can cause damage to your blood vessels.

An increase in heart rate and blood pressure over time wears down your blood vessels causing them to narrow, rupture or leak.

This can lead to heart attacks and even heart failure.

Effects of energy drinks on the brain

As already mentioned, uncontrolled high blood pressure can damage your blood vessels which can also cause blood clots to form in the arteries of your brain. Although it’s not a direct effect on your brain, it can increase your risk of getting a stroke.

Effects of energy drinks on your liver

Energy drinks can cause your liver to become resistant to insulin which can lead to type 2 diabetes.

As we all know, sugar is generally bad for you, however, in small amounts, it doesn’t cause much harm.

Besides containing tons of caffeine, energy drinks also often contain a lot of sugar. If you drink them once in a while there really isn’t any problem. However, drinking these sugary energy drinks frequently will probably cause a rise in your blood sugar levels.

As sugar (glucose when digested) begins to build up in your bloodstream it can cause your liver to become resistant to insulin, which is the hormone responsible for breaking down glucose. Over time this leads to type 2 diabetes.

Here’s a list of the other possible side effects of energy drinks:

  • Insomnia
  • Nervousness
  • Restlessness
  • Irritability
  • Fatigue and sugar crashes
  • Stomach irritation
  • Headaches
  • Chest pains
  • Vomiting

Possible more dangerous effects of energy drinks:

  • Caffeine addiction
  • Tooth decay
  • Kidney failure
  • Dehydration

To be clear, if you go for an energy drink that has a sensible amount of caffeine in it and that is also sugar free, I think that consuming one or two energy drinks a day is no worse for you than drinking one or two coffees a day. In fact, it might even be good for you.

However, just like coffee, if you drink too many energy drinks, it can lead to health problems. So always drink energy drinks in moderation and consult your doctor before making any significant changes to your diet.


If you’re looking for an energy drink that contains a sensible amount of caffeine, but still gives you a great energy boost, REIZE might be the drink for you.

REIZE Energy Drink is very convenient.
Containing only 50mg of caffeine, REIZE provides a great energy boost thanks to all of the other ingredients.

Fun fact!

Unlike your conventional ready-to-drink energy drink, REIZE is a powder energy drink that comes in a cool looking sachet. Just mix it with regular water or any beverage of your choice.


Instant energy whenever you need it.

REIZE is convenient and perhaps the most versatile energy drink that you’ll find. 

For just $1 per drink (including shipping right to your door), REIZE is a lot more affordable than most other energy drinks.

So what are you waiting for?

Give REIZE a try today

Last Updated on

Marty Spargo

I started my own energy drink brand in 2014 and am passionate about educating people about energy drinks so that they can properly understand the ingredients, benefits and risks without being influenced by the marketing messages put out by some brands. You can read my full bio here.

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