The idea that drinking coffee causes dehydration is a myth, affirmed scientists at the University of Birmingham; they demand the actualization of medical recommendations offered to the public to reflect the new discovery. Several cups of coffee per day may hydrate the body just as well as water, the researchers claim.
The idea that drinking coffee leads to dehydration of the organism is over 80 years old (the first study on it has been published in 1928), and it comes from research which showed that caffeine increases diuresis, the elimination of urine through the kidneys and it can cause chronic dehydration. However, the researchers at the University of Birmingham explain that caffeine is not the only active ingredient whose action should be taken into consideration. It is more important to look at the interaction of caffeine and many other components found in coffee. Thus, the 1928 study is not necessarily relevant in modern life.
The scientists decided to verify the above information. They started out by asking 50 healthy men to drink 4 cups of coffee or 4 cups of water each for 3 days. After this time interval, coffee drinkers went on to drink water and vice versa. All participants consumed the same food items during the study and they weren’t allowed to do intense exercise or to drink alcohol.
Blood and urine analysis proved that every single man’s hydration level was the same whether they drank water or coffee, and they eliminated the same amount of urine.
In consequence, coffee doesn’t cause dehydration, at least when it is consumed in moderate quantities. Dr. Frankie Phillips of the British Dietetic Association believes that a small quantity of very concentrated coffee such as espresso may cause slight dehydration, but in regular coffee the diuretic effect of caffeine is counterbalanced by the water content of the coffee; thus, hydration level in the body remains balanced.