The science is in: Coffee does NOT dehydrate you

We’ve long been told a cup of coffee dehydrates you. Even government health recommendations have stated coffee is not appropriate
Health

We’ve long been told a cup of coffee dehydrates you.

Even government health recommendations have stated coffee is not appropriate on hot summer days where dehydration is a health risk.

But scientists have now tested this old assumption… and it’s actually not true.

A 2014 study published in the scientific journal PLoS One found that drinking regular quantities of coffee does not dehydrate you. Coffee simply contributes to your daily fluid intake, much in the same manner as tea or water does.

How did they test it?

In this study, 50 male participants were tested in two phases, where they had to drink four cups of either black coffee (200ml) or water per day for three consecutive days.

In the second phase, participants switched drinks to act as the control. So those who drank coffee for the first three days now had to switch to water, and vice versa. This gives the researchers something to compare the first results to.

“We found that consumption of a moderate intake of coffee, 4 cups per day, in regular coffee drinking males, caused no significant differences across a wide range of hydration indicators compared to the consumption of equal amounts of water,” said lead author Sophie Killer.

In other words, 4 coffees per day for three days straight had absolutely no influence on their hydration status.

But coffee makes me race to the toilet?

If you’re first thoughts were along the lines of “hang on, coffee definitely makes me need to pee”, you’re right.

Caffeine on its own is a diuretic (a substance that promoted the production of urine), much the same as alcohol. However, the caffeine you consume in your coffee comes with at least 200ml of water or milk (or both).

Those fluids offset any fluid loss caused by the caffeine. Put another way, it replaces the fluid you are about to expel, and some. So while a pure caffeine pill consumed without any fluid will dehydrate you, a standard cup of coffee (or four) won’t.

We should always drink a lot of water anyways, regardless of the weather, but it is great news for all of us coffee connoisseurs this summer.

I’ll drink to that, will you?

  1. Four? I have had four coffee’s before 10 o’clock in the morning. Yes. I do have water and milk (no sugar it’s one vice I don’t have) Why don’t they test REAL coffee drinkers. Every coffee works the same way. Why would four coffees be OK and the fifth one any different?

    • The article states that “the caffeine you consume in your coffee comes with at least 200ml of water or milk (or both).and that those fluids offset any fluid loss caused by the caffeine.” So it’s not dehydration.

    • The article states that “the caffeine you consume in your coffee comes with at least 200ml of water or milk (or both).and that those fluids offset any fluid loss caused by the caffeine.” So it’s not dehydration.

    • The article states that “the caffeine you consume in your coffee comes with at least 200ml of water or milk (or both).and that those fluids offset any fluid loss caused by the caffeine.” So it’s not dehydration.

  2. Marg O'Connor  

    Great news, this coffee I just purchased is going down even better now.

  3. I don’t take any notice of any studies these days because they first tell you that something is no good for you, then they say they do a new study and the result of the first study was wrong or in conclusive. It’s a joke and I don’t trust the results.

  4. I beg to differ. Whenever I drink coffee, I need to have a good long drink of water afterwards. This does not happen with any other beverage I indulge in.

    • Linda Eden, coffee and tea do have a diuretic effect but it’s believed that it is not significant enough to dehydrate, however what’s the harm in a glass or 2 of water if one feels inclined.

    • Linda Eden, coffee and tea do have a diuretic effect but it’s believed that it is not significant enough to dehydrate, however what’s the harm in a glass or 2 of water if one feels inclined.

    • Linda Eden, coffee and tea do have a diuretic effect but it’s believed that it is not significant enough to dehydrate, however what’s the harm in a glass or 2 of water if one feels inclined.

    • I like my cup or two in the morning. Who cares if it dehydrates you. Just follow with a glass of water , if you feel thirsty.

    • I like my cup or two in the morning. Who cares if it dehydrates you. Just follow with a glass of water , if you feel thirsty.

  5. I thought it was common knowledge that coffee didn’t dehydrate, mind you, you wouldn’t know from one week to the next whether it’s good for you or not.

    • I agree Fred…don’t know what’s good and what’s not….just cross your fingers and hope for the best .

    • If it’s bad for you, still eat or drink it, for next week they’ll tell you it’s good for you

    • Yep this is soo true. If we stopped eating & drinking all that is supposedly bad for us we would starve to death.

    • Patricia Clapton : Maybe that is the idea, those who follow blindly will be the ones who starve.

  6. I love my ice cold glass of water in summer or winter. Next I love my glass of ice cold white wine with lunch. Next comes a cup of tea. Only drink coffee if there is nothing else.

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