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Next to water, coffee is the favorite drink of the Germans.
April 21, 2025
Birgitta Dunckel
Coffee often has a bad reputation, but drinking coffee in moderation can even reduce the risk of heart and circulatory diseases and protect against some types of cancer. Which coffee is the healthiest, and when should you avoid enjoying it?
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When it comes to coffee, studies are divided: Some scientists see negative health effects from consumption, while others are convinced of its impact on body and mind. In 1991, the World Health Organization even added coffee to the list of potentially carcinogenic substances, but it was rehabilitated in 2016. So what is true: Is coffee healthy or harmful? Or maybe both? A fact check.
One thing is for sure: Besides water, coffee is the favorite drink of Germans. In 2024, per capita consumption was around 163 liters according to the German Coffee Association. That's almost four cups per day.
The popularity of the black hot drink is naturally attributable to its potent wake-up effect – and also its aroma. The caffeine contained in coffee provides the energy boost. The alkaloid stimulates the central nervous system, it also increases pulse and blood pressure, stimulates metabolism and digestion. It also enhances concentration, increases alertness, and improves performance. The invigorating effect usually lasts for several hours and fades after an average of four hours.
Caffeine, like many other things, is all about the dose. Consumed in small amounts, caffeine provides the desired energy turbo; in high concentrations – according to studies, over 400 mg per day – caffeine leads to nervousness, anxiety, and insomnia.
However, judging the right dosage is not so easy. Because you generally don't know how much caffeine is actually in a cup of coffee. This depends on the preparation method and the type of coffee, and – logically – on the size of the cup.
The two main coffee varieties, Arabica and Robusta, differ significantly in their caffeine content, as Robusta contains almost twice as much caffeine as Arabica. Therefore, the rule of thumb is quite weak: A cup of 150 ml filter coffee contains 50-100 mg of caffeine. A strong espresso (50 ml) contains up to 150 mg of caffeine. And even decaffeinated coffee still contains 3 mg of caffeine.
Considering a normal coffee cup as a dosing aid, according to the German Nutrition Society, three to four cups are harmless – one to two for pregnant and breastfeeding women. So, the German consumption is still within the green zone.
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People who have drunk coffee throughout their lives are less likely to develop Alzheimer's and Parkinson's.
Various studies have examined the extent to which coffee—consumed in moderation—can have positive effects on health. And some benefits summarized:
At least six hours before going to bed, you must stop enjoying it: those who drink coffee late have less deep sleep. Consuming coffee in the afternoon or even evening disrupts the levels of hormones such as melatonin. This, in turn, can lead to negative changes in risk factors such as inflammation and blood pressure.
And also the way coffee is prepared seems to be an aspect of its health-promoting effect: According to a study by the Harvard School of Health, simple filter coffee is the healthiest: Because harmful coffee oils, which can raise cholesterol levels, are filtered out of the coffee in this way. Other preparation methods such as espresso, French press, or boiled Turkish coffee are considered unfiltered—and therefore less healthy than filter coffee.
Some medications can be weakened by caffeine. These include:
Caffeine also affects the breakdown of theophylline, a drug often used to treat respiratory diseases. This keeps theophylline in the body longer and can cause unwanted side effects such as nervousness, insomnia, and heart arrhythmias.
The tannins contained in coffee inhibit the iron from iron supplements, so that the body can no longer absorb it. Those who take iron as a dietary supplement should therefore be careful not to drink coffee two hours before and two hours after.
