Exams are upon us once more, which means that coffee is your new best friend: you can easily drink up to six cups a day. But is that good for you? How does caffeine actually work?
By Joris Heijkant / Translation by Sarah van Steenderen

How does caffeine work?

Caffeine helps you concentrate. In the brain, caffeine binds with the adenosine receptors. Adenosine is a neurotransmitter that facilitates sleep. Because the caffeine takes the place of adenosine, your need for sleep decreases and you can work longer. Click on the image to compare the molecules!

Adenosine

Caffeine

Moreover, the caffeine causes the secretion of the neurotransmitter norepinephrine, dopamine, and serotonin in the brain. These have a stimulating effect as well: they keep you awake and give you that typical ‘caffeine rush’.

Good for your heart

So caffeine not only helps you focus, but it is also good for your heart. According to the Nutrition Centre, people who drink two to four cups a day have a ten percent smaller chance of cardiovascular disease or strokes. These positive effects do not apply to children or pregnant women, by the way: they are better off not drinking coffee. Unborn babies can get stressed if their mother consumes caffeine. In young children, it can impede brain development.

Caffeine sources

Coffee is probably the most common source of caffeine. But the substance is found in a host of other products. Test your knowledge below.

There is caffeine in a cup of green tea.

True. A cup of tea contains an average of 30 milligrams of caffeine. Only herbal tea contains no caffeine. Caffeine in tea is also called theine, but that is the exact same substance.

Wrong. A cup of tea contains an average of 30 milligrams of caffeine. Only herbal tea contains no caffeine. Caffeine in tea is also called theine, but that is the exact same substance.

Chocolate contains caffeine.

True. Just like coffee beans, cocoa beans contain caffeine. A bar of dark chocolate contains an average of 40 milligrams of caffeine, which is equivalent to half a cup of coffee. There is less in milk chocolate: an average of 20 milligrams per bar.

Wrong. Just like coffee beans, cocoa beans contain caffeine. A bar of dark chocolate contains an average of 40 milligrams of caffeine, which is equivalent to half a cup of coffee. There is less in milk chocolate: an average of 20 milligrams per bar.

There is more caffeine in a can of energy drink than in a cup of filtered coffee

True. A cup of coffee contains an average of 85 milligrams of caffeine. A can of energy drink has 80 milligrams, which is much less than people think.

Wrong. A cup of coffee contains an average of 85 milligrams of caffeine. A can of energy drink has 80 milligrams, which is much less than people think.

Decaffeinated coffee contains caffeine.

True. Because it is impossible to remove all the caffeine from a coffee bean, there will always be a little caffeine left. But that is only three milligrams per cup. In order to get the same effect as from a cup of regular coffee, you would have to drink almost 30 cups of decaf.

Wrong. Because it is impossible to remove all the caffeine from a coffee bean, there will always be a little caffeine left. But that is only three milligrams per cup. In order to get the same effect as from a cup of regular coffee, you would have to drink almost 30 cups of decaf.

How much is too much?

People respond differently to caffeine. One person might be bouncing around the room after a single espresso, while another might need to have two big cups of coffee before they feel anything. Your sensitivity to caffeine is largely dependent on your weight: heavier people tend to respond less strongly to caffeine. The connection between weight and maximum amount of caffeine works as follows:

Caffeine consumption in the Netherlands

According to the Nutritional Centre, more than 400 milligrams of caffeine a day is too much for the average adults. A lot of Dutch people exceed this limit by a lot: adults ingest an average of 500 milligrams a day. Especially older people consume too much caffeine:

Do you consume too much caffeine?

If you consume too much caffeine, you will start to feel it: restlessness, anxiety, irritability, agitation, muscle spasms, sleeplessness, headaches, nausea, and diarrhoea. Curious to see if you consume too much caffeine? You can calculate it here!

Before we start...





You forgot to fill in your weight! Try again.

How much coffee or tea do you drink per day?

A cup of filtered coffee (125 ml)

An espresso

A cup of instant coffee (125 ml)

A cup of decaffeinated coffee (125 ml)

A cup of black or green tea (125 ml)

How many of these other caffeinated drinks do you consume each day?

A glass of coke

A glass of iced tea (180 ml)

A can of energy drink (250 ml)

An energy shot

How many of these chocolate products do you consume each day?

A cup of chocolate milk (180 ml)

A bar of dark chocolate

A bar of milk chocolate

Results

You consume milligrams of caffeine on a daily basis. That is

Info about you
Adults?
Weight
Your maximum dose of caffeine mg per day
Product Number Total mg
Cup of filtered coffee (125 ml) - 85 mg
Espresso - 65 mg
Cup of instant coffee (125 ml) - 60 mg
Cup of decaf (125 ml) - 3 mg
Cup of tea (125 ml) - 30 mg
Glass of coke (180 ml) - 18 mg
Glass of iced tea (250 ml) - 16 mg
Can of energy drink (180 ml - 80 mg
Energy shot - 80 mg
Cup of chocolate milk (180 ml) - 4 mg
Bar of milk chocolate - 20 mg
Bar of dark chocolate - 40
Total