Coffee Health Facts
Caffeine is a stimulant -- caffeine stimulates the central nervous system (CNS) by its adenosine antagonist action. Moderate doses usually enhance alertness, concentration and energy. These factors also mean that caffeine can interfere with sleep but as most caffeine is excreted in about two hours, this effect is minimal unless the caffeine is taken too soon before falling asleep.
Caffeine also appears to enhance exercise performance, increasing energy, endurance and calorie consumption during exercise.
Caffeine is a diuretic -- ingesting caffeine causes an increase in frequency of urinary excretion. Unless extra water is taken in to compensate for the increased volume of urine that is lost, dehydration can occur.
Caffeine is addictive -- research shows that, although humans seem not to develop tolerance to caffeine (ie, do not need more and more, over time, to get the same results) it does appear that caffeine does cause dependence in humans. This means that the body becomes used to receiving a certain amount of caffeine at regular intervals and temporary effects, such as headache or fatigue, will be apparent each time caffeine is not received when the body expects it. These symptoms are, however, short-lived and usually disappear in several days. Slowly tapering off consumption of caffeine will minimise these effects.
Caffeine does not seem linked to cancer -- in fact, a study in 1986 showed that four cups of coffee per day might actually lower the incidence of cancer compared with non-drinkers.