I just returned from a conference in Seattle, the home to more coffee shops than you can count (including one that you might be familiar with). It got me to thinking about a myth that I hear frequently. Maybe you've heard it too. Does caffeine really lead to dehydration?
Q: When did this myth get started?
A: The caffeine and dehydration concern appears to have roots in a study from 1928, which found that people who drank caffeinated beverages urinated more often. This led researchers to believe that consuming caffeine could lead to dehydration. What is important to remember, however, is that all fluid leads to increased urination. If you drink a liter of water, you will urinate more. It doesn’t mean that you should avoid drinking water.
In 2005, researchers put this myth to the test with a randomized control trial (the gold standard of research) in which 59 men consumed supplemental caffeine for 11 days. No increase in urine volume was found in those who were given caffeine in comparison with the control group. A study in 2014 confirmed these results.
Q: Then why do I feel like I need to go?
A: While you might feel the urge to urinate after a cup of coffee, it’s offset by the fact that coffee, tea, and soda are mostly water. In addition, if you are already well hydrated, drinking more fluids in the form of caffeinated beverages may lead to more urination.
If you choose to get your caffeine boost through pills or energy shots, it may be wise to drink extra fluid, however.
Q: I'm a runner and usually like to have a cup of coffee before my morning workout. Is that going to lead to dehydration?
Many athletes consume a caffeinated beverage before a race or game, and research shows that it does not increase their risk of dehydration.
So enjoy your cup of coffee or tea without guilt or worry. This myth is busted!