How does the body metabolise caffeine?

Posted on 13/09/2021

How does the body metabolise caffeine?

Caffeine does not accumulate in our body, but is broken down in the liver. The liver enzymes responsible for metabolising caffeine are called cytochrome P450 enzymes.

One of them is a key enzyme called CYP1A2, which is responsible for inactivating 95% of all ingested caffeine. The ability to produce this enzyme is coded for by the CYP1A2-gene.

Different people have different versions of the CYP1A2-gene, and these genetic variations determine how active the CYP1A2-enzyme is in each person. This polymorphism divides people into one of two groups.

Someone who produces a very active version of the CYP1A2-enzyme will metabolise caffeine quickly, and it will have a shorter-lasting and mild effect throughout the body. In contrast, a person with a less active version of the CYP1A2-enzyme will inactivate caffeine more slowly and retain it in the body for longer, and therefore experience longer-lasting and more pronounced effects.

Based on these genetic variations, the different versions of the CYP1A2-gene split the population into the aforementioned two major groups


·         Fast-metabolisers

metabolise caffeine quickly, The stimulating effects of caffeine in the body are short in duration. A fast-metaboliser may drink multiple cups of coffee a day.


·         Slow-metabolisers

metabolise caffeine more slowly, so caffeine will be present in the body and brain for a longer period of time. The physiological effects of caffeine, such as increased alertness, will generally