Just caffeine that dehydrates in coffee?

Is it just the caffeine in coffee and Coke/Pepsi that dehydrates you, or is there more to it than that?

Can I drink decaffeinated coffee or caffeine free soda safe in the knowledge I am hydrating myself nicely?

My apologies if this has been asked before. A quick search on “Caffeine AND dehydrate” didn’t show up much, however.


The idea that coffee and soda can “dehydrate” you is part and parcel of the outright LIE that goes along with “75% of Americans are ‘chronically dehydrated’ because they fail to drink eight glasses of water per day.” http://www.snopes.com/toxins/water.htm (be prepared to hear that nonsense over and over and over again from local “news” sources, even though it’s verifiably false.

A quote from the website:

“Regular coffee and tea drinkers become accustomed to caffeine and lose little, if any, fluid. In a study published in the October issue of the Journal of the American College of Nutrition, researchers at the Center for Human Nutrition in Omaha measured how different combinations of water, coffee and caffeinated sodas affected the hydration status of 18 healthy adults who drink caffeinated beverages routinely.
‘We found no significant differences at all,’ says nutritionist Ann Grandjean, the study’s lead author. ‘The purpose of the study was to find out if caffeine is dehydrating in healthy people who are drinking normal amounts of it. It is not.’ The same goes for tea, juice, milk and caffeinated sodas: One glass provides about the same amount of hydrating fluid as a glass of water. The only common drinks that produce a net loss of fluids are those containing alcohol – and usually it takes more than one of those to cause noticeable dehydration, doctors say.”

Thanks, Dogface, that is very interesting.

It is certainly a very widespread theory that coffee/coke dehydrates you more than it hydrates (I was even told this by nutritional sports mags while training for a marathon) so that is quite a turn up! Is this now the generally accepted line of the mainline scientific community, or is it still a hot debate?

So why is caffeine thought of as bad for you if dehydration is a minor issue? I have heard rumours that it increases your heart rate, but is that it?

I think it may be important to remember that people still respond individually to some extent in response to caffeine, and even at that we’re not all regular habituated caffeine consumers. I’d imagine that those concerned with dehydration in the first place are not likely to be caffeine/booze adicts, and may not as habituated as others.

I know for sure that tea, coffee, and pop absolutely do dehydrate me … I can drink a cup of tea and within 30 minutes I will “recycle” that same volume of water right back into the cup (ok, I haven’t gone quite that far yet). If I drink milk, nothing… water, nothing… don’t drink at all, nothing… have a coke and I can tell ya almost to the minute when I’m gonna be looking for the bathroom.