Coffee is a stimulant which postpones sleep. Besides this obvious fact, which is common knowledge, what effects does coffee have on the body. Here is a small list of organs and functions upon which coffee has – or does not have – an effect.


Caffeine acts as a vasoconstrictor on the circulatory system within the brain. It lengthens the duration of vigilance, delays the appearance of symptoms of tiredness, especially during intellectual or repetitive tasks. It prevents migraine, reduces the intensity of migraine headaches and increases the analgesic effect of aspirin. It therefore has a beneficial action.


Among healthy subjects, a normal level of coffee consumption (up to 5 cups spread over the day) will not alter cardio-vascular functions, nor the heart rate, nor blood pressure. However, certain heart disorders mean coffee is not recommended.


Coffee stimulates certain enzymatic activities and thus influences the effect of certain medications.


Effects are variable depending on the subject and the type of physical activity. Caffeine stimulates the central nervous system and increases endurance by delaying the appearance of a feeling of tiredness. It does not improve performance but it facilitates activities that require complex coordination, such as driving machines or vehicles.


Caffeine has a broncho-dilatory action which helps prevent asthma attacks. Dust particles from green coffee beans may nevertheless cause a cutaneous or respiratory allergic reaction.


The wax and fat in coffee stimulate the secretion of acid inside the stomach. They make coffee difficult to digest if it is served with milk.


Caffeine is a diuretic.


Coffee increases external secretions from the pancreas. Diabetics may consume a moderate quantity of coffee unless it leads to a state of nervousness or anxiety, which modify the control of the blood sugar content.


Coffee does not alter the physiological conditions of a pregnancy. It is not dangerous for breast-fed babies. Nevertheless, a fœtus takes a long time to eliminate caffeine and expectant mothers are therefore advised to reduce their coffee intake.


Coffee also contains an acid – chlorogenic acide – which is a powerful, natural antioxidant and which therefore postpones the fixing of atheroma plaques on arteries and delays the development of cardio-vascular diseases.