If you’re one of the millions of regular coffee drinkers in the UK, you might have noticed your go-to drink has lost its caffeinated kick. But, it turns out our bodies have just adapted over time.
NHS surgeon Dr Karan Rajan has shed light on why some people may become resistant to the stimulating effects of caffeine – which is found in lots of foods and drinks. He said: “If caffeine makes you feel tired, it might be because of a software glitch in your caffeine gene.”
He outlined that everyone can either be fast or slow caffeine metabolisers. That decision is made for us by one liver enzyme known as CYP1A2. This is what affects the body’s sensitivity to caffeine, determining the speed at which one metabolises it.
The NHS medic added that people can take anywhere “from two to eight hours” to break down caffeine. Whilst it’s in our system, caffeine works by blocking off adenosine receptors that typically slow nerve activity, thereby keeping us alert and awake.
He continued: “People with a fast-metabolising mutation break down caffeine more quickly, so those adenosine receptors free up more quickly. This allows the sleep-inducing chemical to bind, making you feel more tired.”
If you thought that simply increasing caffeine intake could sort out this issue, you’re wrong. It turns out that our nervous system has a defence mechanism in mind that can effectively develop a tolerance to caffeine.
Dr Rajan explained: “If you regularly consume lots of caffeine, and those adenosine channels are constantly blocked, then your body actually does a system update and compensates by producing even more adenosine receptors in your brain. It does this to regulate your sleep cycle so you don’t glitch out.”
The NHS advises that caffeine should be consumed in moderation to avoid negative effects. Caffeine is present in a variety of items, not just coffee and energy drinks but also teas, fizzy drinks, chocolate, and certain health supplements.
Consuming over 600mg of caffeine daily ( the equivalent of six mugs of brewed coffee ) may cause anxiety, insomnia, agitation, palpitations, diarrhoea, and restlessness. Those looking to cut down on caffeine should try decaffeinated alternatives or gradually reduce their caffeine intake.