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Is 8 Glasses of Water Per Day Overkill?
An anonymous reader writes: "David Harris reports in his science news that the American Journal of Physiology today published a study dispelling the 8x8 myth. That is, the recommendation to drink 8 eight-ounce glasses of water per day has no scientific evidence behind it. The paper also mentions the risks of drinking too much water and explodes some other urban myths of water drinking such as the 'thirsty means dehydrated' and 'dark urine means dehydrated' myths."
For once, the /. article summary says nearly as much as the linked-to articles themselves. It's funny, no matter how hard I try to challenge preconceived notions I have, there's always one more "well-known fact" I forget to look into.
The part about water in caffeine drinks counting towards you're recommended intake struck me as most contrary to my own anecdotal expereience--it seems like whenever I drink anything caffeinated, I'm thirsty for water shortly afterwards. I suppose this discrepancy is either in my head, a bizarre artifact of my own physiology, or a misinterpretation of the abstract linked to here.
It pisses me off that i can't read this without paying. I mean all were getting here is the watered down abstract. And the link will likely be hosed shortly anyway due to ./ effect.
I always thought it was cans of Coke!
I might have to re-evaluate my daily drinking.
no sig.
I think this paper is clear evidence that we all need to drink more Bawls. :)
Learn to Play Go
Yup. NPR had a story with the author of this study this morning, quite interesting too...
Guest host Renee Montagne talks with Dr. Heinz Valtin, doctor of physiology and professor emeritus at Dartmouth College, about a new study saying that people may NOT need to drink eight cups of water a day to stay healthy.
story on npr.org
Lets hope they got over the deep linking craop.
.....
Not a Sop to Drink (February 6, 2001)
Water - the myth of 8 glasses (February 13, 2001)
How much water do we really need? (May 24, 2002)
There's pretty close to 12 ounces of water in a 12 ounce can of soda, but with caffeine you'll probably pee out 14 ounces.
'SBEMAIL!' is better than a goat!!
Drinking water is good for you. Drink lots of water. When it is hot, humid, and I am outside, I can drink that 64 oz of water within an hour or less. The people who don't drink enough water get taken away in an ambulance.
You are orders of magnitude more likely to experience dehydration than to experience the almost mythical "water intoxication." (Yes, it is possible to kill yourself by drinking too much water, but it happens very very rarely.)
So ignore this article and go have a nice glass of water.
Tim
Omnia vestra castrorum habetur nobis.
You doctors have been telling us to drink eight glasses of gravy a day!
Y2K Compliant since the late 1890s
I used to drink about six cans of Diet Coke a day, plus one Diet Coke from the soda fountain at lunch.
A friend I respected suggested that I consider drinking more water and less soda. He claimed that I would lose weight (I was 265 pounds at the time) and feel better.
What I discovered is that I did lose weight, although not enough to significantly impact my appearance, but more to the point I felt better - I was generally more alert in the afternoons, and after a while just a few sips of a Diet Coke would give me more energy (when I needed it) than a whole one would previously.
It looks like caffinee becomes steadily less effective as more of it is used, so the simply exponent of abstaining from it and limiting its intake worked well.
So I would recommend something like this to anyone trying to become more healthy. I started losing weight at a good clip, incidentally, when my new job responsibilities made me less sedentary. Annoying but good for me in the long term.
D
I'm feeling a bit drained....
* And remember, it's spelled N-e-t-s-c-a-p-e, but it's pronounced "Mozilla."
It's recommended that people taking certain recreational pharmaceuticals put a limit on their water consumption, since some have an anti-diuretic effect.
You can get water from sources other than just a glass of water - for instance, all those servings of fruit you never eat.
1) It is true that 8 glasses of water need not be drunk each day. It *is* true that the equivalent, two liters of fluid, must be consumed -- but food contains 30-50% of the water you need each day.
2) It is true that "being thirsty means you're already dehydrated" is an exaggeration, but it is an intentional one. It means "you're well on the way to being dehyrated". The exaggeration is, I suppose, intended to catch ID10Ts who ignore thirst even during 10-km runs in 110 degree weather. Thirst does kick in well after you have lost plenty of fluid, and once ADH (anti-diuretic hormone, the hormone that controls urine production and volume status) has already risen. These facts, I suppose, are the origin of the common anecdote.
3) "Dark urine doesn't mean you are dehydrated" -- not true. It *is* true that it is difficult to judge from color alone. Despite our 16 million color resolution, it is hard for people to subjectively grade color without experience (i.e. working in a urinalysis lab); thus, judging hydration by urine color alone will have a high error rate and often be inconclusive. Other factors, such as urine contaminants, might make the test less accurate. Along with other clues, however (i.e., being sweaty, thirsty, and tired), it may be useful.
4) "Water intoxication", a peculiar form of hyponatremia (low blood sodium concentration), is *not* mythical. However, it *is* much rarer than dehydration. It takes a special kind of person (read: mentally ill patient) to drink the 25+ glasses of water per day that it requires to achieve this.
5) Studies have shown (sorry, I don't have links, its 0130 around here) that caffinated beverages such as Coke hydrate at about 2/3 the rate of pure water. That is, at Coke concentrations, the caffeine dose is sufficient to cause you to lose 1/3 of the water you just drank as part of the Coke.
6) These indicators -- thirst and dark urine -- are not "myths" and not useless (although they are far from perfect). I happen to know first-hand that some of the best doctors in the United States use these observations in their daily assessments of patients.
7) "Absence of evidence is not equal to evidence of absence." --paraphrased from Carl Sagan
This fellow has done very little experimentation on his own, but simply collected the lack of research combined with evidence from his own student experiments over the years. While this is a provocative article, it is intended to stimulate research, and NOT to be the definitive work on the subject. What's needed (as he states at the end, in A CALL FOR DIALOGUE) is more and better (and better funded, pretty please)nutritional research!
Disclaimer: IANAD (but I am in medical school and work with 'em in hospitals every day; see address.) And yes, I am a geek. Been programmin' since age four (BASIC on a c64), researchin' at MIT. Good enough for youz?
Your friendly neighborhood nitpicker
After this story, and one yesterday aboutt he size of drinks cups also in ounces, I've looked up the conversion rates to see what you're all talking about
from this web site :
1 American fluid ounce = 29.57 millilitres.
1 British fluid ounce = 28.41 millilitres
So the American 8oz cup is just under a quarter litre (or around halfway between a 1/3 and a 1/2 English pint, if that's more your kind of reference size....)
Peeing WHITE?! WHITE?! If you pee white, please go see a doctor - you're pipes are crossed somewhere.
Usual color scale:
Clear.. okay.
Light Yellow.. okay..
Thick lemonaide yellow.. drink water..
Tang Orange.. Someone slipped me some pyridium.
Red.. time to see the doctor
White.. WTF?
This guy shows a substantial amount of evidence that most of the supposed benefits of drinking "lots" of water are either unsupported by research or shown to be achieved with substantially less water intake than the 64oz recommendation. He also has some anecdotal evidence that caffinated beverages and to some extent beer not being particluarly dehydrating.
But the most important thing to note (I think) is that under normal circumstances the body's thirst mechanism is entirely sufficient to prevent dehydration.