How does caffeine work? It’s all down to brain chemistry!



This week we’re welcoming back our guest blogger Helena Hills of Truestart Coffee again. In this article, Helena explains how caffeine works and what effect it has on the body and the brain.  

Adenosine builds up

Adenosine is a neurotransmitter – basically a brain messenger. When you’re awake, adenosine builds up in your brain so you know when you are tired. It binds to adenosine receptors, which causes you to feel drowsy by slowing down nerve cell activity.

Caffeine gets involved

To the receptors, caffeine looks just like adenosine. This allows caffeine to bind to the adenosine receptors in the same way, but they do not slow down brain activity like adenosine would. The caffeine is blocking the adenosine from binding to the receptors and speeding up nerve cell activity rather than slowing it down.

The result is that you feel more alert and less tired.

Flight or fight?

Caffeine also causes increased neuron firing in the brain. Your pituitary gland then releases hormones to tell your adrenal glands to produce adrenaline. Why does it do this? Because it thinks the increased neuron firing is an emergency, so wants your body to produce a ‘fight or flight’ response. This causes your heart to beat faster so you feel excited, your muscles to tighten up ready for action, and your liver to release sugar into your bloodstream for extra energy. Clever, right?

How much caffeine is safe?

Too much caffeine can cause problems including jitters, heart palpitations and headaches. The European Food Safety Authority recommends that you try to limit your caffeine intake to 400mg per day (or 200mg when pregnant or breast feeding). This is an amount that they have researched to be safe. (Bodyshot: your sensitivity to caffeine can be determined by a DNA test if you’re curious).

Whether it’s a scoop sachet or Hero bar, one serving of TrueStart Coffee contains 95mg of caffeine, so you can enjoy four per day and feel confident that you’re safely under the recommended caffeine limit! With any other coffee, you could be pushed over your daily limit in just one serving.

Want to try TrueStart? Use coupon code ‘BODYBOOST’ to get 25% of your first order until the end of May when you visit

Bodyshot is a health and fitness consultancy that helps busy professionals get more energy by removing the guesswork around their health, fitness and nutrition. Visit or email to register your interest in our services and connect with us on FacebookInstagram and Twitter.

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