For many people, the day only really begins after a cup of coffee. One sip and you immediately feel more alert. We owe this stimulating effect to caffeine, the most popular stimulant in the world. We drink it in coffee, tea and energy drinks, eat it in chocolate and even find it in some supplements. But what actually happens in your body when you consume caffeine? In this article, you will discover how it works, what benefits it offers and what disadvantages you should be aware of.
In this article, you will read:
- What caffeine is
- What caffeine is found in
- What effect caffeine has on your body
- How you can reduce the effects
What is caffeine?
Caffeine is a natural substance with a stimulating effect, found in many plant species. The most well-known source of caffeine is coffee, but it is also found in tea leaves, cocoa beans and guarana seeds. After drinking coffee, your gastrointestinal tract absorbs the caffeine very quickly. In the liver, it is converted into paraxanthine, theophylline and theobromine, which then reach your brain.
Where is caffeine found?
Caffeine is not only found in coffee, but also in many other drinks and foods. For example, a 200 ml cup of filter coffee provides about 95 mg of caffeine, while a 30 ml espresso contains about 63 mg. A cup of black tea contains an average of 40-50 mg, and green tea about 30-35 mg. Matcha is more concentrated: 1 gram of powder contains 60–70 mg of caffeine. Soft drinks and energy drinks also contain caffeine, with a glass of cola containing 18 mg and an energy drink containing 80 mg. And last but not least: dark chocolate contains 14 mg per 30-gram serving. By adding up all these sources, you can get a good idea of your total daily caffeine intake.
How does caffeine work in the body?
Caffeine works in different ways in your body. Normally, a substance called adenosine binds to receptors in your brain. Adenosine sends signals that warn you that it is time to rest or sleep. Caffeine blocks these receptors, causing those ‘rest signals’ to be ignored. This is why you feel more alert and less sleepy after a cup of coffee or an energy drink.
At the same time, caffeine stimulates the release of adrenaline, the stress hormone that prepares your body for action. This causes an accelerated heart rate, increased blood pressure and a temporary stimulation of your metabolism. It also releases dopamine, a substance that makes you feel pleasant and motivated. The combined effect of these processes is that you feel more energetic, alert and focused.
You will usually notice the effects within 15–45 minutes after consumption, and they can last for several hours, depending on your personal sensitivity and the amount of caffeine you have consumed.
Positive effects of caffeine
- Increased alertness and concentration
Caffeine stimulates the central nervous system, allowing you to react faster and focus better. Moderate amounts of caffeine (approximately 75–250 mg) can improve alertness and concentration, especially in situations of fatigue or sleep deprivation. This makes it easier, for example, to perform complex tasks or get through long working days without mental dips. - Improved athletic performance
Caffeine increases endurance and reduces feelings of fatigue during exercise. This allows you to train harder and persevere longer during exercise, resulting in better performance. - Mood boost
By releasing dopamine and other “feel-good” neurotransmitters, caffeine can provide a short-term feeling of pleasure, motivation and energy. This effect can help you start your day on a positive note or get through an afternoon slump. - Faster reaction time
Caffeine can improve your reflexes, which is useful for sports, driving or activities that require quick decisions.
These benefits are usually most pronounced with a moderate dose, such as one to two cups of coffee or an equivalent amount of caffeine (100-200 mg). However, too much caffeine can negate the positive effects.
Disadvantages of too much caffeine
Although caffeine can make you alert and energetic, it can also have disadvantages:
Affecting sleep quality: If you drink coffee or energy drinks in the afternoon or evening, even one cup can reduce your sleep quality, especially if you are sensitive or slow to break down caffeine. The half-life of caffeine, the time it takes for half of it to be broken down, averages around four to six hours, but can vary from person to person.
Heart palpitations or slight increase in blood pressure: In people with heart or vascular problems or slow caffeine metabolism, even a small dose can be noticeable and cause an unpleasant feeling of heart palpitations.
Stomach problems: Caffeine stimulates stomach acid production. This is not a problem for most people, but for those with a sensitive stomach or conditions such as reflux or gastritis, it can lead to heartburn, bloating or pain behind the breastbone.
Acceleration of bowel movements: Caffeine stimulates the central nervous system and the muscles in the intestines. This causes the intestinal wall to contract more quickly (peristalsis), which can accelerate bowel movements. This is why some people need to go to the toilet quickly after a cup of coffee or suffer from cramps, especially when drinking coffee on an empty stomach or having several cups in quick succession.
Anxiety and irritability: Caffeine stimulates the central nervous system by increasing the production of adrenaline and other stress hormones. At the same time, it blocks the calming substance adenosine in the brain, causing nerve signals to continue firing and cortisol levels to rise. This provides a short energy boost, but can also make sensitive people feel agitated. The body experiences this as a stress response, which can manifest itself in nervousness, restless thoughts, irritability or even feelings of panic.
Habituation: In addition, regular intake can lead to dependence: if you stop suddenly, withdrawal symptoms such as headaches, irritability and fatigue are possible.
How much caffeine is safe?
We often only experience the disadvantages of caffeine from around 400 mg per day for adults, which is equivalent to about four cups of coffee. This amount is therefore considered safe.
Not everyone processes caffeine at the same rate. People who are sensitive to caffeine or break it down less quickly, such as pregnant women, may feel these effects even at lower amounts. Pregnant women are therefore advised not to exceed 200 mg per day. Children and teenagers are more sensitive to the stimulating effects and may experience heart palpitations or sleep problems more quickly. Certain medications or conditions, such as high blood pressure, can also enhance the effects.
Hormones and your cup of coffee: how your cycle affects the effects of caffeine
Did you know that your body's response to caffeine can vary greatly during your menstrual cycle? This is because hormones such as oestrogen and progesterone fluctuate. In the first half of the cycle, when oestrogen levels rise, caffeine is often broken down slightly faster, so you feel the stimulating effects for less time. Around ovulation and in the luteal phase, progesterone increases, which can actually slow down the breakdown; the same amount of coffee can then cause more heart palpitations, nervousness or sleep problems. Just before menstruation, when many people are more sensitive to mood swings or fluid retention, caffeine can also exacerbate symptoms. By adjusting your intake to your cycle, for example by consuming less caffeine in the second half, you can better cope with these hormonal influences.
Practical tips
These tips can help you experience fewer of the disadvantages of caffeine:
- Combine with food: do not drink coffee or tea on an empty stomach, but first eat something containing protein and fat (such as nuts, yoghurt or avocado). This helps to slow down the absorption of caffeine, making the effect more gradual and reducing the likelihood of a sudden energy spike followed by a crash. It also often reduces stomach and intestinal complaints.
- Hydrate sufficiently: in addition to coffee and tea, drink enough water to help your body break down the caffeine and reduce headaches or feelings of agitation.
- Choose milder varieties: green tea and matcha contain caffeine, but in lower doses and often in combination with calming substances such as L-theanine. This means you won't experience a short energy spike followed by a crash, but a more even and long-lasting boost in alertness and concentration.
- Know your sources: caffeine is not only found in coffee, but also in tea, energy drinks, chocolate and some supplements. This means you can consume much more than you expect without realising it.
- Drink chamomile tea: have you had too much caffeine? Chamomile tea relaxes the nervous system, aids sleep and soothes the stomach if you experience any caffeine-related symptoms.
- Listen to your body: are you experiencing heart palpitations, inner restlessness or sleep problems? Then this is a sign to drink less caffeine.
Alternatives for an energy boost
Want a pick-me-up without extra caffeine? Try a few simple and healthy alternatives: drinking enough water, taking a short walk, getting some fresh air or taking a power nap can give your energy and concentration a significant boost. In addition, eating regularly and choosing fibre-rich, complex carbohydrates helps to keep your blood sugar stable.
Getting enough vitamins and minerals, such as B vitamins, magnesium and iron, also provides your body with a natural energy supply. Read here which vitamins can help with fatigue. These are simple ways to get a long-lasting and steady energy boost, without the nervousness or dips that sometimes occur with caffeine!
Conclusion
Caffeine can give you that extra boost: you feel more awake, sharper and often happier. But if you overdo it, sleepless nights, restlessness and dependence lurk around the corner. So listen carefully to your body, stay within the recommended amount and enjoy your coffee or tea with attention. This way, you get the best out of caffeine without experiencing the downside.
