Ultimate guide to caffeine

Caffeine: Your Ultimate Guide

Coffee is the largest source of caffeine in the diet. You can expect around 95 mg of caffeine from an average cup of coffee. However, this amount varies from coffee drink to coffee drink and can range from almost zero to over 500 mg. Here is a detailed guide to the caffeine content of different types and brands of coffee.

You probably use caffeinated stimulants such as coffee, tea, and cocoa to keep fit over a long working day. However, caffeine is more than just a pick-me-up. Like any so-called psychotropic substance, caffeine affects your state of mind, elevates your mood, and boosts circulation and metabolism.

If you want to make even better use of caffeine and its positive effects, you have the option of not only consuming caffeine in coffee or other drinks, but you can also use caffeine in a targeted manner with the help of certain dietary supplements.

A whole range of different caffeine supplements is available to you, with which you can guarantee an ideal caffeine dosage. The result: You’re fully engaged in sports and at work.

What is the effect of caffeine on the human body?

The caffeine’s effect occurs at the cellular level, namely on the nerve cells, i.e., those responsible for passing on information in your body.

Caffeine has a chemical structure similar to your body’s own substance, adenosine. This can throttle the ability of nerve cells to work by attaching themselves to specific receptors.

Because of its similarity to adenosine, caffeine can occupy the same receptors without sending the message to the nerve cells to work less. In this way, caffeine maintains your productivity and performance over a more extended period of time.

In addition to stimulating the nervous system, caffeine has the following effects:

  • Increased ability to concentrate and alertness
  • The heart beats faster and stronger
  • Heart rate and blood pressure increase
  • Widening of the blood vessels, especially in the arms and legs
  • Digestion and metabolism work more actively

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Caffeine and its effects on the body

Caffeine takes effect after just 30 minutes and is distributed throughout the body via the blood. The effects of caffeine last about four hours:

  • High doses of caffeine make the heart beat faster and increase the pulse. Blood pressure also rises in people who rarely consume caffeine.
  • Even in small doses, caffeine can improve concentration and temporarily eliminate tiredness.
  • Caffeine also often constricts the blood vessels in the brain and can thus relieve mild headaches and migraines.
  • The muscles can be better supplied with oxygen when we consume caffeine. That’s why some athletes take caffeine before training, for example, in the form of tablets.
  • However, our body gets used to caffeine with regular consumption. This habituation shows that many of the mentioned modes of action occur only weakly or not.

Can you overdose on caffeine?

Consuming too much caffeine can result in a caffeine overdose. Doctors speak of an overdose of one gram of caffeine. This corresponds to 15 to 20 cups of espresso. Symptoms include:

  • Sleep disorders
  • Restlessness
  • Headache
  • Nervousness
  • Panic Attacks
  • Gastrointestinal complaints
  • Circulatory collapse

Some of the symptoms don’t even require an overdose—they can occur with overconsumption. However, this is usually harmless because of the said habituation effect, so many people can tolerate several cups of coffee in a row.

According to the European Food Safety Authority, 200 mg of caffeine per single dose and 400 mg daily are safe for humans. Children should consume a maximum of 3 mg of caffeine per kilogram of body weight.

How does caffeine reduce fatigue?

With caffeine in coffee, espresso, tea, or other caffeinated stimulants, your tiredness is sometimes far away. How can this effect of caffeine be explained?

The chemical structure of caffeine causes several positive caffeine side effects. By stimulating the cardiovascular system, your heart pumps faster, resulting in faster oxygenation. Your blood contains more oxygen and flows faster because the blood vessels dilate.

As a result, your muscles and central nervous system are better supplied and can therefore work better.

How long does caffeine work in the body?

The effects of caffeine extend over the period from caffeine absorption into the bloodstream to breakdown and elimination. After a cup of coffee, cola, or an energy drink, it takes about 45 minutes for the caffeine to get into your blood.

How long the effects of caffeine then last depends on how quickly your body can break down the caffeine. Experts usually speak of a minimum effect time of four hours. [3]

With very high doses of caffeine over a long period of time, your body becomes accustomed to this chemical and forms strategies to weaken the effects of caffeine. You get used to it after about two weeks of heavy coffee consumption or heavy caffeine intake.

So that you don’t have to do without a warm, delicious drink in the morning but still give your body a break from caffeine, we recommend that you try decaffeinated coffee from time to time.

Health benefits of caffeine

Coffee is rich in antioxidants, and many studies show it is good for your health.

However, too much caffeine has been linked to adverse effects such as anxiety, trouble sleeping, heart palpitations, and restlessness.

Caffeine consumption of 400-600 mg/day is not associated with adverse effects in most people. That equates to about 6 mg/kg (3 mg/lb) of body weight or 4-6 average cups of coffee per day.

That being said, caffeine affects people very differently. Some are very sensitive to caffeine, while others are unaffected by significant amounts. This is primarily due to genetic differences.

You just have to experiment and see what amount suits you best.

Coffee as a stimulant

Coffee is popular for its stimulating properties, which become apparent when caffeine affects the central nervous system. Caffeine is psychoactive, affecting how your brain and nervous system work, which can alter your mental state. It does this by blocking neuroreceptors that promote relaxation and sleep, allowing you to be more alert and focused.

Caffeine and hair growth

Caffeine has been known for its invigorating effects on the body for many years. A scientific study has shown that caffeine promotes hair shaft lengthening, resulting in a prolonged anagen growth phase in both men and women.

What you need to know about caffeine dosage

Consuming high amounts of caffeine regularly can lead to side effects such as tiredness and nervousness. For this reason, a proper dosage of caffeine is essential. Basically, you should pay attention to your body and see how strongly it reacts to caffeine.

Consumption of 400 mg caffeine per day with a body weight of 70 kg is considered harmless. This corresponds to 5.7 mg of caffeine per kilogram of body weight.

Why do some coffees have more caffeine in them?

The caffeine content of coffee depends on many factors, such as:
  • Type of coffee beans: There are many different types of coffee beans, which can naturally contain varying amounts of caffeine.
  • The roast: Light roasts have more caffeine than dark roasts, although the darker roasts have a deeper flavor.
  • Type of coffee: The caffeine content can vary widely between regular brewed coffee, espresso, instant coffee, and decaffeinated coffee.
  • Serving size: “A cup of coffee” can range from 30-700 ml (1-24 oz), significantly affecting the total caffeine content

Bottom line: The caffeine content depends on the type of coffee bean, the roast, the method of preparation, and the serving size.

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How much caffeine is in a cup of coffee?

The most crucial caffeine content factor is the coffee you drink.

Brewed coffee

Brewed coffee is the most common way to brew coffee in the US and Europe. Also known as regular coffee, brewed coffee is made by pouring hot or boiling water over ground coffee beans, which are usually placed in a filter. A cup of brewed coffee (8 oz) contains about 70-140 mg of caffeine, an average of about 95 mg (1, 2).


Espresso is made by forcing a small amount of hot water or steam through finely-ground coffee beans.

Although espresso contains more caffeine per volume than regular coffee, the caffeine content per serving is typically lower because espresso servings tend to be small. A shot of espresso typically contains around 30-50 ml (1-1.75 oz) and around 63 mg of caffeine (3). A double shot of espresso contains around 125 mg of caffeine.

Espresso-based beverages

Many popular coffee drinks are made from espresso shots mixed with different types and amounts of milk. These include lattes, cappuccinos, macchiatos and americanos. Since the milk does not contain additional caffeine, these drinks have the same caffeine content as a straight espresso. A single (small) espresso contains on average about 63 mg of caffeine, a double (large) espresso contains about 125 mg.

Instant coffee

Instant coffee is made from brewed coffee that has been freeze dried or spray dried. It’s usually in large, dry chunks that dissolve in water. To make instant coffee, simply mix a teaspoon or two of dried coffee with hot water. Brewing is not necessary. Instant coffee usually contains less caffeine than regular coffee. A cup contains around 30-90 mg (4).

Decaffeinated coffee

Despite the name, decaffeinated coffee is not entirely decaffeinated. It can contain varying amounts of caffeine, ranging from 0-7 mg per cup, with the average cup containing 3 mg. However, some varieties may contain even higher amounts of caffeine depending on the type of coffee, decaffeination method, and cup size.

Bottom line: The average caffeine content of a brewed 8-ounce cup of coffee is 95 mg. A single espresso or espresso-based drink contains 63 mg, and decaffeinated coffee contains an average of 3 mg of caffeine.

Coffee shops are also notorious for their large mugs, which can be as large as 700 ml (24 oz). The amount of coffee in such cups corresponds to about 3-5 standard cups of coffee.

Are caffeine tablets harmful?

Caffeine tablets work just like the caffeine in coffee and tea. However, it is highly concentrated and can be taken at any time. A caffeine tablet usually contains 200 mg of caffeine and thus the maximum single dose.

For many people, caffeine tablets are better tolerated than coffee. Because the acid contained in coffee can lead to stomach problems.

However, the high dosage should only be taken if you are already used to caffeine. Otherwise, symptoms such as restlessness, nervousness, and sleep disorders can quickly occur.

Like other caffeinated foods, caffeine pills can only mask tiredness. The effect of the tablets abruptly wears off over time. Therefore, you should not use them as a pick-me-up when driving.

Bottom line

There is no definitive answer as to whether caffeine is healthy or not. Caffeine works similarly to other psychoactive substances but is not counted as an addictive substance.