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Is coffee diuretic?

rppa

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Aside from getting into a medical question of interest to me as a voluminous coffee-drinker, this topic also gets into the area of subjective vs. objective evidence which has been raised in many threads in different areas of this forum.

OK, let me start here:

http://bicyclecoffeesystems.com/

This guy is a rabid coffee drinker, and has done a fair job of collecting papers supporting his habit, i.e., supporting the thesis that there is no harmful effect, especially diuretic, from coffee. (Look for the heading "Coffee and Dehydration--Urban Myth" just below the pictures of bicycle-compatible coffee bottles).

These papers make a convincing case that there is no difference in fluid retention from drinking coffee.

Yet I have personal evidence that suggests some connection to dehydration. Some of it is weaker than others, but taken together I feel there's something at odds with the conclusions of those papers, and I want to reconcile it.

Weakest: Coffee affects my singing voice. I'm an amateur singer, no pro but I've sung in some decent choirs and in some stage shows. If I have anything challenging to do (meaning high notes) then coffee seems to have a repeatable negative effect: if I have coffee at all in the hour or so before a performance, I'll choke and cough or otherwise strain myself trying to get the notes. Tea doesn't have this effect (which suggests it's not the caffeine). The best thing is water, especially hot water.

Arguments against this: there is lots of lore in the singing world, some of it scientific, some of it superstition. Singers, like most performers, are a superstitious lot, and one of the biggest enemies of the singing voice is tension. Conceivably, coffee could make me tense just from worrying about it. On the other hand, there could be a physiological connection of coffee -> tension which wouldn't require the "diuretic" explanation.

Stronger: A day of coffee affects my body like a day of not drinking at all. I try to get in 6-8 glasses of water a day. If I do, I wake up feeling good in the morning. If I have little or no liquid during a day, then several physical symptoms will manifest themselves in the morning. From least to most severe (in some cases I get only the first couple, in worst cases all four):

- a lot of coughing in the morning
- (apologies for too much information) strongly-colored urine
- a very dry mouth, to the point where I can barely swallow until I get a little water.
- headaches

I associate all of these symptoms with dehydration from not drinking water. The thing is, I also associate these symptoms with a day in which I have drunk a great deal, almost all of it coffee. This experiment is repeatable.

As I enjoy coffee, I'd be happy to do any controlled experiment anyone wants to suggest. I'll deal with the headaches in the interests of science.

Discussion?
 
No objective data, but personal anecdote...

Damn right it's diuretic. I find shortly after coffee I have a full bladder in a way that is untrue if I drink anything else except alcohol. Odd thing I also find is that after coffee I often experience what the medics call "urgency", i.e. get out of my way or there's going to be a wet patch, that is disproportionate to the volume of urine present.

I think I am quite sensitive to caffeine, and my unblinded observations reveal that I get a noticeable hand tremor if I drink too much coffee and it does seem to be able to induce cardiac 'palpitations'.

So, there you go, in some ways more information than you could ever have wanted, yet not enough to answer your question!
 
Badly Shaved Monkey said:
Odd thing I also find is that after coffee I often experience what the medics call "urgency", i.e. get out of my way or there's going to be a wet patch, that is disproportionate to the volume of urine present.
Click to expand...
It appears that in addition to being a diuretic, caffeine also irritates the bladder, hence the effect described here. Try googling the words caffeine, bladder and irritant.
 
The thing with pregnancy (Coffee FAQ 2.3) is interesting. The first symptom of pregnancy for both of my wife's pregnancies was an aversion to coffee. A friend of ours of Italian heritage (with all that implies about a love for strong coffee) also had a strong aversion to coffee throughout her pregnancy, and immediately after giving birth had such a strong craving that she literally crawled to the nearest vending machine to get a cup.

The fact that there's data on fetal malformation, however weak, must mean that there are some women who do not experience this aversion and continue to consume coffee during pregnancy.
 
Mojo said:
It appears that in addition to being a diuretic...
Click to expand...

And yet, and yet...

http://www.ncbi.nlm.nih.gov/entrez/...ve&db=PubMed&list_uids=12187618&dopt=Abstract

Investigations comparing caffeine (100-680 mg) to water or placebo seldom found a statistical difference in urine volume. In the 10 studies reviewed, consumption of a CB resulted in 0-84% retention of the initial volume ingested, whereas consumption of water resulted in 0-81% retention. Further, tolerance to caffeine reduces the likelihood that a detrimental fluid-electrolyte imbalance will occur.
Click to expand...
 
rppa said:
This guy is a rabid coffee drinker, and has done a fair job of collecting papers supporting his habit, i.e., supporting the thesis that there is no harmful effect, especially diuretic, from coffee. (Look for the heading "Coffee and Dehydration--Urban Myth" just below the pictures of bicycle-compatible coffee bottles).
Click to expand...

Here's the quote:

"The logic goes like this: Diuretics cause dehydration. Caffeine is a diuretic. Coffee contains caffeine. Hence drinking coffee causes dehydration. The flaw in this logic is that coffee is NOT mostly caffeine, it is mostly water. The water provides hydration, while the small amount of caffeine has negligible or no effect."

A diuretic causes you to lose more water, but that doesn't produce dehydration unless you don't drink enough water. Period. And caffeine is diuretic, which means coffee is diuretic, period. But it's only in extreme cases (amoebic dyssentry, for example) where you can't solve the problem of dehydration by simply drinking more water, so this is really beside the point to begin with.
 
Mojo said:
It appears that in addition to being a diuretic, caffeine also irritates the bladder, hence the effect described here. Try googling the words caffeine, bladder and irritant.
Click to expand...

Look at the last link I found;

"increase in detrusor pressure on bladder filling following administration of caffeine"

I assumed that was more likely to be a direct sympathomimetic effect of the caffeine, increasing bladder wall tone for a given volume. But, you suggest another mechanism, but I'm not sure they are contradictory.

An increase in detrusor pressure could be perceived as 'irritation', or it could be the other way round, so that irritation results increased wall turgor.
 
Re: Re: Is coffee diuretic?

Ziggurat said:

A diuretic causes you to lose more water, but that doesn't produce dehydration unless you don't drink enough water. Period. And caffeine is diuretic, which means coffee is diuretic, period. But it's only in extreme cases (amoebic dyssentry, for example) where you can't solve the problem of dehydration by simply drinking more water, so this is really beside the point to begin with.
Click to expand...

Wait, I'm confused. So coffee is diuretic just because of the presence of caffiene? What about, like the guy said, the relative amounts of caffiene versus water in a cup of joe? And I'm not sure I understand your point about amoebic dysentery. And I'm also not sure what you mean by "this is really beside the point." What this does your this refer to? :confused: :confused: :confused:
 
Re: Re: Re: Is coffee diuretic?

Phaycops said:
Wait, I'm confused. So coffee is diuretic just because of the presence of caffiene? What about, like the guy said, the relative amounts of caffiene versus water in a cup of joe?
Click to expand...

A diuretic means something that makes you secrete more water from the kidneys (and often the intestines as well). Coffee does that, hence it's a diuretic. That is a somewhat SEPARATE question from whether the net hydration effect of the water in the coffee outbalances the dehydration effects of the caffeine.

And I'm not sure I understand your point about amoebic dysentery. And I'm also not sure what you mean by "this is really beside the point." What this does your this refer to? :confused: :confused: :confused:
Click to expand...

It's beside the point because, even if you lose more water from drinking coffee than you gain from it (my intuition is that this varies from person to person - it's quite diuretic for me), that really doesn't matter from a dehydration standpoint since you can just drink more water to compensate.

In the case of severe disease (such as dysentery) or poisoning, you're often losing too many electrolytes along with the water, and simply trying to drink more water to compensate doesn't work (you'll end up like that frat kid who died from drinking too much water). But that's irrelevant for coffee, since you're not perturbing your system nearly that much. So the question of whether coffee is good or bad for you (which is really what that guy's kick seems to be) doesn't even depend on whether or not it's a net dehydrator for you. If it is, then just drink more water along with your coffee and it won't hurt you at all (aside from the inconvenience of having to empty your bladder more often).
 
Thanks for the clarification.

So is it true that if you're more used to caffiene, it doesn't dehydrate you as much? How does that work? You're just immune to the effects, or your body compensates?
 
From this page:

Tea Drinking and Fluid Balance: A Review

(Maughan 2001 See References)

Tea contains caffeine making it a diuretic. The common view is that caffeine from drinking tea will cause dehydration by increasing urine production leading to lost water needing to be replaced to maintain fluid balance. This actually is not entirely correct….It is true that caffeine is a diuretic – it is metabolised in the liver by the p450 system to produce; dimethyl- and monomethyl-xanthines, xanthine and uric acid. (Maughn & Griffin 2001). It is the increase in uric acid (which needs to removed from the body via the kidneys) that causes more urine to be produced. Water is needed to dilute the uric acid to prevent any damage and maintain correct fluid and ion balance. Caffeine may also increase glomerular filtration rate and reduce sodium reabsorption from the renal tubules, thus increasing the amount of water in urine.Studies that have been conducted on the effect of caffeine and tea on fluid balance have produced the following conclusions (Maughn & Griffin 2001);

Large doses of caffeine (above 300 mg/more than 6 cups of tea per day) have an acute diuretic action.
Single caffeine doses at the levels found in commonly consumed beverages have little or no diuretic action (as the potential fluid loss due to the caffeine is replaced by the fluid in the drink itself).
Regular caffeine users become habituated to the effect of caffeine, diminishing its actions.In summary, drinking tea can actually contribute to the recommened fluid intake of 1.5 – 2 litres of fluid per day to maintain good body fluid levels rather than diminish them. Other health benefits include its antioxidant properties (e.g. oxidising LDL (for reducing cardiovascular disease), inhibting cell proliferation and trapping carcinogens (to prevent cancers), and protecting teeth (from acid erosion).
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I also seem to recall another study (that I'm too lazy to search for right now) which says that some people's smooth muscles are more sensitive to caffeine and so it may increase their urge to urinate to a greater degree. People with a degree (not necessary pathological) of urinary incontinence will be more sensitive to caffeine. But even for them the diuretic effect can almost disappear if they keep it at 2 mugs of coffee per day.
 
"Large doses of caffeine (above 300 mg/more than 6 cups of tea per day) have an acute diuretic action."

6 cups of tea a day! Goodness knows how much caffeine I'm ingesting a day, I normally have around 12-15 cups of THE Tea everyday. Hmm... did wonder why I'm always rushing to the loo ;)
 
rppa said:
The thing with pregnancy (Coffee FAQ 2.3) is interesting. The first symptom of pregnancy for both of my wife's pregnancies was an aversion to coffee. A friend of ours of Italian heritage (with all that implies about a love for strong coffee) also had a strong aversion to coffee throughout her pregnancy, and immediately after giving birth had such a strong craving that she literally crawled to the nearest vending machine to get a cup.
Click to expand...

I'm currently pregnant, and one of my first symptoms was caffiene aversion. Tea and cola were two things I loved, and when I got pregnant the very thought of them was horrifying.

One of my aunts had the same thing. It doesn't appear to be overwhelmingly common, but it certainly seems to be a not unusual symptom.

My liking of caffiene came back at the start of the third trimester, actually. I've been avoiding it, just because why ingest something that might not be healthy at this point? But the cravings/liking have definitely returned.
 
I just performed a very scientific test of the diuretic effects of caffeine. First, I drank a very large cup of coffee (about 16 ounces). Then, after about an hour with no obvious diuretic effect, I drank a 1 liter Mountian Dew, which contains pretty high levels of caffeine. An hour later, I still did not observe any diuretic effects. I then took a sip of water from the drinking fountian and five minutes later I had to run to the restroom. Based on these observations, I can only conclude that water, not caffeine, is the cause of the diuretic effects.
 
Maybe I'm being stupid, but I still haven't figured out a conclusion from all this. I see there's evidence for bladder irritation by caffeine.

But how about my central question: does coffee cause dehydration? I've got the personal evidence that the water content in coffee does NOT replace the fluid lost from caffeine effects, and then the medical evidence that coffee does not cause net fluid loss.

So which is it? Dammit, I'm thirsty after coffee, despite the claim that it's equivalent to drinking a cup of water. Is there objective scientific evidence to bolster my personal observations? Does coffee cause dehydration or not?
 
My completely anecdotal conclusion based on a convenient mix of personal observations and gleaned studies is that a concetration of about 25mg of caffeine in 100ml of water will not cause net loss of water to most people, assuming they stay below a total of 300mg of caffeine per day.
 
rppa said:
Maybe I'm being stupid, but I still haven't figured out a conclusion from all this. I see there's evidence for bladder irritation by caffeine.

But how about my central question: does coffee cause dehydration? I've got the personal evidence that the water content in coffee does NOT replace the fluid lost from caffeine effects, and then the medical evidence that coffee does not cause net fluid loss.

So which is it? Dammit, I'm thirsty after coffee, despite the claim that it's equivalent to drinking a cup of water. Is there objective scientific evidence to bolster my personal observations? Does coffee cause dehydration or not?
Click to expand...

rppa-- I'm not convinced that your observations show that coffee causes dehydration in you. Coffee has lots of other things in it besides caffiene and water. Perhaps your feeling of thirst has something to do with its acidity? If you put sugar in your coffee, does that have any effect on how you feel? A headache the day after may be unrelated, or not related to dehydration, at least. Maybe you're allergic to some trace chemical in coffee. Do better quality coffees make you feel the same way? Etc. etc. etc.

IOW, your personal experiences may not be evidence of what you think they are, and can't confirm or deny the hypothesis that cofee causes you to become dehydrated without ruling out countless other factors.

In my personal experience, coffee used to cause me great....gastrointestinal distress, let's just say. Then, around late high school sometime (yes, I started early!), I switched over to "gourmet" coffee from Folger's. What a difference! I could get through my whole day without feeling like my stomach was being twisted and burned and stabbed with tiny little knives all at the same time. I wasn't running to the bathroom as soon as I got to school. In this case, it would appear that my reaction to the coffee had nothing to do with either fluid content or caffiene, but rather something else in the coffee. I don't think this is proof one way or the other, but it's just a story related to cofee for me to tell so I can fit in :(
 
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