People around the world love coffee. It’s one of the most popular drinks, often used to start the day or keep energy up during work or study.
But not everyone’s body handles coffee the same way. Some people can drink a lot and feel fine. Others get jittery or have trouble sleeping after just one cup. Scientists have been trying to understand why this happens.
A team from the University of Toronto, led by researcher Ahmed El-Sohemy, looked into how our genes affect the way we process caffeine—the main active ingredient in coffee. Caffeine is a natural substance that makes you feel more awake and alert.
But once it enters your body, your system has to break it down and remove it. That job mainly falls on your liver, and how fast this happens depends on your genes.
Genes are like tiny instruction books inside your body. They tell your body how to make proteins that do all sorts of important work. One of these genes is called CYP1A2. It helps your liver break down caffeine.
Some people have a version of this gene that works quickly—like a fast car on an open highway. These people can drink three or four cups of coffee a day without much issue. Their bodies get rid of the caffeine fast, so it doesn’t build up and cause problems.
But others have a slower version of this gene. Their bodies take longer to break down caffeine—like a car stuck in traffic. For them, drinking too much coffee can be hard on their system, especially on the kidneys.
The kidneys are organs that help clean your blood. They remove waste and extra fluids, and they help keep your body’s chemicals balanced. If your body is slow at handling caffeine, drinking too much coffee might put extra stress on your kidneys. That’s why scientists often say that three cups of coffee per day is a safe amount for most people.
What’s really interesting is that the global population is almost evenly split. About half of people have the fast version of the CYP1A2 gene, and the other half have the slow version. So, your reaction to coffee may be very different from your friend’s, just because of your genes.
You can find out how your body handles caffeine by taking a simple genetic test. Knowing your type could help you make better decisions about your health. If you’re a slow caffeine processor, cutting back on coffee might protect your kidneys and help you sleep better, too.
This research, shared in the medical journal JAMA Network Open, could help more people understand how their bodies work. It also opens the door to learning more about how our genes affect how we react to food, drinks, and even medicine.
Next time you sip your coffee, think about whether your body is more like a race car or a slow-moving truck. Either way, knowing yourself better can help you stay healthy and feel your best.
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