For the vast majority of adults, caffeine is a consistent part of their daily routine. Many people can’t start their day without their morning brew. But everyone reacts to caffeine differently. Some people get the jitters from low-caffeine tea, others can drink an espresso in the evening and fall asleep soon after without an issue. So why is this the case? It may surprise you to learn that caffeine sensitivity is related to your DNA.
There are a variety of factors that can affect your sensitivity to caffeinated drinks, and your genes are a big one. Here, we explain how caffeine sensitivity works, how genetics and other factors contribute, and more.
Caffeine sensitivity is mainly a matter of metabolism
When you drink a caffeinated beverage, the caffeine quickly enters your bloodstream, which is when you start to feel its effects. From there, it’s gradually broken down by an enzyme in the liver. On average, it takes around five hours to remove half of a given dose of caffeine, but this number can be higher or lower depending on the efficiency of your liver enzyme.
If you have a very efficient enzyme, your liver can remove caffeine from your blood faster, meaning that you won’t feel its effects as strongly or for as long. On the other hand, if your enzyme is less efficient, more caffeine stays in your bloodstream for longer. Not only does this mean that you’ll feel the effects for a prolonged period of time, it also means that it’s much easier to have too much caffeine. This kind of slow caffeine metabolism is generally responsible for what we commonly refer to as caffeine sensitivity.
However, some aspects of caffeine sensitivity are related to how caffeine affects us. The reason caffeine makes us feel alert is because it binds to receptors in the brain that normally bind to adenosine, a molecule that our brains use to make us feel sleepy. When caffeine binds to these receptors, adenosine has nowhere to go, so we don’t feel its effects. It’s possible to have adenosine receptors that are more or less willing to bind to caffeine molecules, which is why some people barely feel any energy boost from caffeine or can drink it late in the day without it affecting their sleep.
Symptoms of caffeine sensitivity may sound familiar
Anybody who consumes too much caffeine at once may experience uncomfortable symptoms. But for people who are truly sensitive to caffeine, it takes much less caffeine to cause these symptoms:
- Anxiety
- Headache
- High blood pressure
- Insomnia or disrupted sleep
- Increased or fluttering heart rate
- Jitters
- Nausea
The role of genetics in caffeine sensitivity
Both aspects of caffeine sensitivity that we’ve discussed are determined by specific gene variants:
- CYP1A2 variants are responsible for how fast or slow you metabolize caffeine.
- ADORA2A variants determine the sensitivity of adenosine receptors, with certain variants being associated with higher rates of caffeine-related sleep issues and anxiety.
Other factors can make some people more sensitive to caffeine than others
Your genes play a large role in your relationship with caffeine, but there are other factors that may also have an effect, including:
- Age – Children are more sensitive to caffeine than adults. Our liver enzymes also start to become less efficient at processing caffeine as we get older.
- Certain medications – Stimulants like ephedrine and theophylline can increase the intensity of caffeine’s effects. And oral birth control decreases caffeine metabolism.
- Health conditions that overlap with sensitivity symptoms – If you already have a health condition like insomnia or anxiety, you’re more likely to experience negative effects when you consume caffeine.
- Pregnancy – Being pregnant reduces your caffeine metabolism. Experts also recommend limiting caffeine intake while pregnant and breastfeeding, as caffeine can be passed to the baby.
- Smoking status – Smoking tobacco increases your caffeine metabolism.
Learn more about your sensitivity to caffeine
How you experience caffeine may be influenced by multiple different factors. If you have a history of avoiding caffeine because of negative side effects or if you need to consume large amounts in order to get an energy boost, it probably has something to do with your genes. myGenetics can help you find out for sure.
myGenetics is a community research program that uses DNA testing to screen for a variety of genes associated with food intolerances and sensitivities. Plus, you can find out if you have risk factors for breast cancer, ovarian cancer, Lynch Syndrome and hereditary high cholesterol. There’s no cost to participate, and health insurance is not required.
