10 facts about coffee

It was long thought that coffee made you ill. Today, its beneficial properties are increasingly being highlighted. So what is true?

19.12.2017 Carmen Schmidli 4 minutes

Caffeine is a poison. It serves to protect plants from being eaten by paralysing or killing insects. A healthy adult would have to consume 10 grams of caffeine to ingest a deadly dose – that equates to more than 330 cups of espresso. However, even just one gram can cause minor poisoning. Caffeine is contained in coffee, cola, energy drinks, black tea and maté tea as well as – in small quantities – in cocoa. Consumers appreciate its stimulating effect. It is the most frequently consumed psychoactive substance in the world.

What effect caffeine has

First and foremost, caffeine is a stimulant. It keeps you awake, improves your mood and encourages drive and concentration.

Nerve cells communicate with each other using messages. This process consumes energy, leading to a release of adenosine which protects the brain from overexertion. The exchange of signals between nerve cells is inhibited and you get tired. The caffeine blocks these adenosine receptors by occupying them. As a result, the adenosine is ineffective and cannot make you tired.

The myth of drying out

Coffee does not dry out the body. It is considered to be a source of liquid and can be counted towards the recommended daily intake of about two litres. The glass of water often served with an espresso or cappuccino is not intended to replace the lost liquid, but rather – just like during a wine tasting – to neutralise your sense of taste. So you drink it beforehand, in order to be able to better enjoy the coffee flavour.

However, coffee is not suitable for quenching your thirst. Water or unsweetened herbal tea are much more suitable for this purpose. Coffee drinks from the chilled section also often contain a lot of sugar. The Schweizerische Gesellschaft für Ernährung (Swiss Society of Nutrition) therefore recommends looking at the nutrition declaration and the list of ingredients.

What is a safe level of caffeine consumption?

Adults can safely consume up to 400 milligrams of caffeine spread out over the course of one day, i.e. almost four cups of coffee. However, the caffeine content varies depending on the type of coffee bean and method of preparation. Too much caffeine causes symptoms like anxiety, facial blushing, excitation, unrest, palpitations or nausea. The symptoms disappear as soon as the substance has been excreted.

Does it weaken or strengthen you?

Coffee was long considered unhealthy. However, according to Peter E. Ballmer from Winterthur Cantonal Hospital, there are now indications “that the beneficial effects of moderate consumption outweigh the risks”. For instance, coffee is said to be good for diabetes patients because it enhances the effect of insulin. Studies have also shown that coffee drinkers are less likely to get colon cancer or that consumption thereof prevents arteriosclerosis. According to other studies, coffee possibly improves elderly people’s memories and reduces the risk of getting Alzheimer’s.

However, the results should be taken with caution because they are based on experiments with animals or cell cultures. Or they are observational studies which are considered less meaningful.

What contains how much caffeine

Coffee (150 ml)

150 mg Caffeine

Chocolate (100g)

90 mg Caffeine

Energy drink (250 ml) 

80 mg Caffeine

Black tea (150 ml)

50 mg Caffeine

Cola (330 ml)

40 mg Caffeine

Espresso (30 ml)

30 mg Caffeine

Full milk chocolate (100g) 

15 mg Caffeine

Cocoa (150 ml)

5 mg Caffeine

Who should refrain from consuming caffeine if at all possible?

Children react to caffeine with hyperactivity and sleeping disorders. A daily intake of three milligrams per kilogram of body weight is considered a safe level. The Schweizerische Gesellschaft für Ernährung recommends that pregnant women consume a maximum of 200 milligrams per day. In animal experiments, caffeine led to growth retardation, memory disorders and epileptic fits in both foetuses and newborns. “However, it can improve the pulmonary function of premature babies,” says Christa E. Müller, a caffeine expert at the University of Bonn.

How quickly coffee takes effect

Do you feel chirpy after the first sip? It’s all in the mind. Caffeine’s maximum effect only occurs 30 to 45 minutes after consumption once the caffeine has entered the gastrointestinal tract and spread throughout the body. It then takes several hours for the body to break down the caffeine. The half-life is specified as being about three to five hours.

It is still unknown why caffeine affects some people quicker than others. On the other hand, it is well researched how the caffeine affects the different organs and bodily functions: better blood flow to the organs, greater heart activity, increased intestinal activity or, for example, a stimulating effect on the psyche.

What effect drinking coffee in the evening has

People react differently to caffeine. The best thing to do is to find out how much you can tolerate. Some people sleep restlessly after drinking a cup of coffee in the evening because the REM phases which help to make you feel refreshed are disturbed. “However, there are also people who sleep better after drinking coffee,” says Peter E. Ballmer, Head of the Clinic of Internal Medicine at Winterthur Cantonal Hospital and a nutritional expert.

How addictive coffee is

Christa E. Müller, who is conducting research into caffeine at the University of Bonneven, says that although caffeine has not officially been classified as an addictive substance, it does in fact make people addicted. The body gets used to the regular consumption of caffeine, even in small quantities. If the accustomed active substance is not consumed, the body might respond with withdrawal symptoms. Typically, such symptoms include headaches and difficulty concentrating. However, this abstinence can also trigger depressive moods and irritability. The symptoms can be severe at the beginning, but the worst will be behind you after nine days at the most.

What people with high blood pressure should know

Consumption of moderate amounts of caffeine is perfectly safe. Although the substance stimulates circulation, makes your heart beat faster and raises your pulse and blood pressure, it does not do so on a scale which would endanger your health. Furthermore, regular consumption of coffee lessens this effect. Moderate consumption also poses no risk of contracting arteriosclerosis or having a heart attack. Patients with heart rhythm problems should be careful. They should preferably ask their doctor if it is advisable to drink coffee.

This article was first published on Beobachter Gesundheit (in German): Advice, tips on prevention and well-being as well as information on illnesses and symptoms.

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