This is what the Flemish Institute for Healthy Living (VIGL) has to say about caffeine:
Caffeine is a substance that has a stimulating effect on the central nervous system. In small amounts caffeine can:
- have a positive effect on concentration and performance,
- elevate the attention span, alertness and motivation, and
- remove the sense of fatigue or lower drowsiness.
Different brewing methods and the type of coffee (robusta of arabica, MASL,…) have a big impact on how much caffeine there will be in a cup of coffee.
But why does a coffee plant even produce caffeine? The explanation is quite simple: to keep the insects away by paralysing them. What instantly explains why coffee plants that grow at high altitudes – where it is colder en less insects survive – produce less caffeine. Plants that grow in a warm valley, will produce more caffeine.
Besides having a stimulating effect on our fatigue and concentration, caffeine also is performance-enhancing. What probably explains the large numbers of cycling tourists in coffee shops… Until 2004 caffeine was on the list of forbidden substances released by the IOC!
Which type of coffee contains the biggest amount of caffeine? Espresso or slow brew? Most people will think espresso, but in reality that is actually not the case. An espresso does have a higher percentage of caffeine, but the total volume of an espresso is only approximately 20ml. A doppio is double that amount. A mug of slow brew is about 200ml, sometimes even more.
But such a big mug can take a while to drink. An espresso is consumed much faster, so the intake of caffeine happens quicker, what might explain the so-called ‘caffeine-shot effect’.