Coffee - why it is healthier than you think

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.

What effect does coffee have on the body?

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.

Coffee: How much per day is healthy?

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.

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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.

The positive effects of coffee on health

Various studies have examined the extent to which coffee—consumed in moderation—can have positive effects on health. And some benefits summarized:

1. Drinking coffee regularly can apparently prevent depression. Two to three cups a day reduced the risk of illness in women by 15 percent, and with more than three cups, the risk even decreased by 20 percent.
2. People who have been drinking coffee all their lives are less likely to develop Alzheimer's and Parkinson's.
3. In combination preparations against headaches, caffeine increases the pain-relieving effect of painkillers by up to 70 percent.
4. The risk for type 2 diabetes decreases by six percent with each cup of coffee you drink daily. Overall, you can reduce your risk by up to 30 percent.
5. People with asthma show improved lung function up to two hours after consuming coffee.
6. A number of studies conclude that coffee drinkers are less likely to develop liver cancer. Whether coffee protects against other types of cancer has not yet been clearly proven. Conversely, however, the following applies: coffee does not increase the risk of cancer. However, it should not be consumed too hot, as hot liquids promote esophageal cancer.
7. According to numerous studies, coffee reduces the risk of cardiovascular diseases.
8. A South Korean research team even concluded that two to four cups of coffee a day reduce mortality. This may be due to the antioxidants contained in coffee.

Filter coffee is the healthiest

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.

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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.

Taking medications: Beware of interactions with caffeine

Some medications can be weakened by caffeine. These include:

1. Sedative medications (benzodiazepines)
2. Thyroid hormone replacements
3. H1-antihistamines

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.

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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.