Drinking 8 Glasses Of Water A Day Is 'Nonsense,' Doc Says

The health recommendation to drink six to eight glasses of water a day is "thoroughly debunked nonsense," a doctor wrote this week in a commentary in the British Medical Journal.

Many health departments and organizations tout the need to drink that much water every day, but there is no high-quality scientific evidence to support the recommendation, wrote Dr. Margaret McCartney, a general practitioner based in Scotland.

Some organizations backed by bottled-water makers -- such as Hydration for Health, created by the makers of Volvic and Evian -- say that it's important to drink 1.5 to 2 liters (about 6 to 8 cups) of water a day, and that being even mildly dehydrated plays a role in disease development, McCartney wrote.

However, no such claims have ever been confirmed in studies, she said, and drinking too much water can actually be dangerous by causing low blood sodium levels (a condition called hyponatraemia) and exposing people to pollutants in the water.

"People still think that we're all going to die or our kidneys will shrivel up if we don't drink eight cups of water a day," McCartney told Postmedia News. "From what I can see, there's never been any evidence in the medical literature about it."

The first recommendation to drink six to eight glasses of water a day has been traced back to a 1945 U.S. research paper, but even that isn't for certain, Postmedia News reported.

The Guardian reported that humans' thirst mechanisms are so sophisticated that if our bodies are in need of water, they'll let us know by making us thirsty.

From The Guardian:

Drinking extra water is said to reduce urinary tract infections, improve skin tone, help with weight loss (fill up with water first), reduce headaches and fatigue, eliminate constipation and improve concentration. There's no robust evidence for any of this. The kidneys are wonderful things (that don't need flushing with lots of water) and will make concentrated urine to save water.

Dartmouth Medical School physician Dr. Heinz Valtin also told The Huffington Post last month that there aren't any scientific studies supporting the eight-glasses-a-day rule and that, to date, he hasn't seen any additional evidence that would confirm the recommendation. Valtin published a review of the literature in the American Journal of Physiology.

Not all doctors are on board with McCartney's commentary. The commentary wasn't peer-reviewed, one doctor from King's College London pointed out, and it's especially important for the very young and the very old to be appropriately hydrated, particularly by drinking water, the Los Angeles Times reported.

The Mayo Clinic acknowledges that most doctors recommend drinking eight to nine cups of water a day, but said that people need to drink as much water as is necessary to replace water that is lost throughout the day.

In addition, drinking enough to produce about 6.3 cups of clear or slightly yellow urine a day means your fluid intake is probably sufficient, the Mayo Clinic said.

There are factors that can increase or decrease your body's need for water, though, including an increase in physical activity, being sick (vomiting or diarrhea), being in a dry environment or at a high altitude and being in hot or humid weather, according to the Mayo Clinic.

And it's not just water -- fruit and vegetables can also hydrate you, research shows. A University of Aberdeen Medical School study revealed that fruits and vegetables can hydrate the body twice as much as a glass of water because of the salts, sugars and minerals they contain, the Daily Mail reported.

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Comments

[anytimecowboy]

03:38 PM on 07/18/2011

I teach healthcare. For over a year, I have told students that if they bring me the study showing 8 glasses of water is necessary they will get a degree without going to school. No one has brought me the study because it does not exist. Now let's debunk the MSG theory.

[DoYourThang]

02:29 PM on 07/21/2011

Dr. F Batmaghelidj studied the effects of dehydration for many years before passing away. I heard him discussing his book "Your Body's Many Cries for Water" with Dr. Gary Null on the radio about ten years ago. Four years later I started getting arthritis and Googled his book. I am sure that what I learned from him helped me to overcome arthritis by drinking more water and eating sea salt the way he discusses it in his book.

Here are some links from a website that more than covers the results of his research:

Water Cure "brief"
http://www.watercure2.org/preventable%20_cause_of_diseases.htm

Water Cure Disclaimer:
http://www.watercure2.org/disclaimer.htm

Testimonials of people who have done the water cure for diabetes:
http://www.watercure2.org/diabetes.htm

Testimonials of people who have done the water cure for heart problems:
http://www.watercure2.org/heart_problems.htm

Water Cure Recipe:
http://www.watercure2.org/mankind.htm

Other Testimonials, including cancer:
http://www.watercure2.org/table_of_contents.htm

All about the "Water Cure":
http://www.watercure2.org

[DoYourThang]

03:01 PM on 07/21/2011

If you had trouble viewing the first link above you can also view it by going to http://www­.watercure­2.org scroll down until you see a white box and select the link in that white box that says "THE SIMPLE PREVENTABLE CAUSES OF MOST SO-CALLED DISEASES"
Be sure to read the powerful testimonials at this site of people who have found that it works!

[Waterphoneman]

10:31 AM on 07/18/2011

Your body is not stupid. When you get thirsty drink, when you are not thirsty, don't drink.

[Momcatusa]

08:45 AM on 07/18/2011

I notice a lot of careless throwing about of the words "cup" and "glass". 8 cups of water per day is NOT the same as 8 glasses of water per day. I have glasses which range from 3 oz to 18 oz in my kitchen - imagine trying to drink 8 of the 18 oz glasses of water every day! That's what, 144 ounces? In liquid measurement, a cup is a specific amount, 8 ounces, so 8 cups would equal 64 ounces, or roughly 2 liters - easy enough to drink if you are exercising, perhaps doing yard work or out on the boat for the day. I'm not advocating superhydration here, I'm just saying that 8 cups got expanded to 8 glasses pretty easily, and that changed the whole sense of the thing.

[bumbalina831]

12:43 PM on 07/17/2011

I've never drank 6 to 8 glasses of water a day. I couldn't handle it. I have also never been dehydrated because I do drink some water, just not that much or a beverage when I'm thirsty. I'm happy to read this article, which proves to me a lot of things. Thanks for the info, it is much appreciated.

[expat50]

12:37 PM on 07/17/2011

When someone told me "if you get thirsty, it's too late - you are dehydrated" I asked them then what role does thirst play? I asked if millions of years of evolution would have retained and refined the thirst mechanism if it was not useful. The answer was vague, something about "they say." I am glad to see this type of article.

[longnow]

08:02 AM on 07/17/2011

The 8 glasses a day crap did conveniently coincide
with the bubble in bottled water with or without the
convenient nipple to complete the infantile PR
symmetry. Just imagine all that leaching plastic baking
in the hot sun in trucks coming all the way from
Fiji and sometimes from the tap water up the block.

[paradoc2]

10:43 PM on 07/16/2011

If you are eating and drinking enough to maintain a normal weight and feel decent then you should be fine.

[charpist5]

05:18 PM on 07/16/2011

If I drank 8 glasses of water,
I'd waddle around like an otter.
The bathroom I'd live in,
My bladder would give in,
I'd spend my whole day on the potter.

[charpist5]

05:15 PM on 07/16/2011

I drink very little water (or any fluids) for reasons i will not go into here. Probably....three glasses of water every day....I have perfect skin, great health, lots of energy, etc. I do not do alcohol, coffee or tea. Very little juice (OJ is high sugar), so mostly I drink plain water.

[don28don]

04:52 PM on 07/16/2011

One of the biggest scams in the history of the world was bottled water. The same idiots that buy bottled water will next buy bottled air.

[ddermon]

04:14 PM on 07/16/2011

Use a little common sense. Your weight, the temperature, your exercise level, your diet, the relative humidity, your age all are factors which affect your hydreation requirements. No one size fits all. If you run one mile per day, in 10 minutes, in New Hampshire, in March, you won't need the water that a person running 3 miles a day in 20 minutes in Central Florida will. A 225 lb sedentary 51 yr old man needs less water than a 24 yr old female, world class, soccer player. Think, people. If you are going to cut the lawn, drink before, during and after your done. Less if it's cool out, More if it's hot. Simple rule: If you are sweating alot, drink some water, Cool water. Too little is bad and too much is bad. Learn your own bodily needs and listen to your body. If you are to err on one side or the other, err SLIGHTLY on too much. If you were wrong........ go pee.

[pepperoni0]

04:01 PM on 07/16/2011

My cardiologist told me to cut down on caffeine and drink 64 oz of water or equvalent liquid per day as a way to avoid the arrythmia and heart beat skips I was experiencing. It worked for me, so why should I give any credibility to some MD who wants to get his name in the paper? There may be no evidence in the macro sense, but there certainly is in the personal experience of people with bonafide problematical medical symptoms. Does Dr Valin know something that nobody else knows? I think not. Drink up!!

[Victoryin2008]

09:35 AM on 07/17/2011

I'm happy your doctor's advice worked for you. Perhaps it wasn't the 64oz of water/liquid per day that did the job, but the omission of caffeine from your diet? Caffeine is known to cause a rapid heart rate. Aren't you at least curious about the fact that the new "fad" of drinking lots of water coincided with the appearance of bottled water? (LOL). The body is a wonderful instrument...it lets us know when we need rest and water. Perhaps Dr. Valtin DOES know more than the rest of us (who are not scientists).

[Barbara Folk]

10:42 AM on 07/23/2011

Not exactly... Back in the 90s, I was told to drink water because I had "concentrated urine" when doing a test for a bladder infection. Admittedly, I wasn't drinking water because it hurt to pee, but when I did drink more, it never bothered me at all. And usually, I did drink about 10 glasses or so a day. Even now, I tend to down about 5 or 6 bottles (I rinse them and refill) every day. I won't credit them with miracle cures, because I'm also taking supplements, but I can tell when I don't get enough water pretty easily.

[bumbalina831]

12:45 PM on 07/17/2011

That's great but what works for you may not work for us all.....just saying.

[Victoria Cianci Cipullo]

03:40 PM on 07/16/2011

Love cold water, especially in the winter in NJ. the best water, I feel in the country. But, if I drank 8 full glasses a day I would get me sick

[MikeLoran]

03:38 PM on 07/16/2011

Have a Bun test with your next blood test, it will tell you if you are drinking enough liquid.

[AverageJoeSixPac]

03:23 PM on 07/16/2011

Beer is appx 94% water and tastes 94% better. 8 to 10 glasses a day.

[sheila3fan]

09:41 PM on 07/16/2011

alcohol will dehydrate your system even more, think, rubbing alcohol drys the skin, as will beer dry your innards rule of thumb, for ever beer drink 8oz. of water

[Thaag Tidestalker]

03:53 AM on 07/17/2011

I would drink all that beer if they could make a NA beer that actually tasted as delicious as the real thing. Unfortunately, the calories get me every time.