Myth Busted – Coffee Doesn’t Cause Dehydration


Water is undoubtedly the elixir of life. Without it our bodies will cease to function within 3-5 days, a remarkably short period of time. For years we’ve often heard that coffee causes dehydration and that we should supplement every cup of coffee consumed with a cup of water. At best we’re told to not count coffee towards our daily intake of water.

New research from the University of Birmingham (1) is challenging this theory and claiming that there is no evidence that the moderate consumption of coffee has no impact on our levels of hydration.

With an estimated 1.6 billion cups of coffee consumed every day it’s surprising that relatively little research has been conducted on this subject. It’s an intriguing question and the initial hypothesis was that coffee consumption would contribute to our daily fluid requirements and would not result in progressive dehydration.

52 males aged between 18-46 were selected from an initial group of 100 volunteers. Those selected had to be in good overall health, free from medication, have a stable weight and work/live in an environment that avoided excess humidity. Women were excluded from the study to avoid potential fluid variations during their menstrual cycle.

The men were split into two groups where the first group drank black coffee for 3 days while the others consumed water. At the end of this first phase both groups were given a 10-day “wash out” period before their roles were reversed.

The tests continued for 72 hours and scientists monitored a number of variables including dietary intake, urinary markers and blood samples.

At the end of the test they found no correlation between coffee consumption and dehydration with a wide variety of markers suggesting that consuming coffee was equal to water in terms of hydration levels.

The additional argument we frequently hear is that coffee consumption increases our need for urination. When the University of Connecticut examined a number of previous studies (2) on urination and coffee consumption, they found that 12 out of 15 comparisons highlighted no difference between the frequency or amount of urination when people drank either coffee or water.

There is growing evidence to suggest that coffee may not be as bad for us as we once thought, and moderate consumption may actually help with hydration, not inhibit it.

About the author: Nick Huxsted is an independent writer who’s interested in biology and the effects coffee has on the human body. He currently writes for Joe Black Coffee in Liverpool and is a regular contributor to Hip & Healthy.



1 – Killer S.C., Blannin A.K. and Jeukendrup A.E. (2014). No evidence of dehydration with moderate daily coffee intake: a counterbalanced cross-over study in a free-living population.

2 – Departments of Kinesiology, Nutritional Sciences, and Physiology & Neurobiology, University of Connecticut, Storrs, CT 06269-1110, USA.



Nick Huxsted
Nick Huxsted works for Will Williams Meditation in London. Their aim is to help people live the happiest, healthiest lives they can through the ancient practice of Vedic meditation.