While it is often suggested that diuretic coffee causes dehydration, a study from the University of Birmingham (UK) published in the specialist journal Plos One, reveals that moderate coffee consumption does not dehydrate and that, on the contrary, it has the same virtues as water.
Researchers compared the effects of drinking coffee and water and assessed their hydration abilities. In this crossover study, 50 healthy, non-smoking men drank 4 x 200 ml cups of coffee containing 4 mg of caffeine per kilogram or an equivalent amount of water for 3 days.
The hydration levels in the blood and urine of the volunteers were measured before and throughout the experiment.
Coffee hydrates as much as water
Researchers found no difference in hydration levels between coffee drinkers and water drinkers. But because caffeine increases renal sodium excretion, coffee drinkers had higher urinary sodium levels.
“We found that moderate coffee consumption did not change hydration levels when compared to equivalent water consumption,” said Sophie Killer, director of the study. This study would therefore call into question the effects of dehydration often suggested by coffee. But if the authors of this study conclude that “coffee consumed moderately does not dehydrate”, they recall that the study was carried out on healthy people, not subject to urinary disorders or to risks of dehydration, and that these results should not be extrapolated to the entire population. “
