April 02, 2008
No Health Benefit Seen From Extra Water Consumption

I'm glad to see some medical experts have taken the time to write up a review of the lack of evidence for the claims that many glasses of water per day help you stay healthy. The idea that high water consumption delivers a health benefit is just a legend.

Washington, DC (Friday, March 28, 2008) — A recent look at what is known about the health effects of drinking water reveals that most supposed benefits are not backed by solid evidence. The findings indicate that most people do not need to worry about drinking their recommended 8 glasses of 8 ounces (“8x8”) of water per day. The editorial is published in the June 2008 issue of the Journal of the American Society of Nephrology (JASN).

While it is clear that humans cannot survive for longer than several days without water, very little research has assessed how average individuals’ health is affected by drinking extra fluids. Experts have claimed that ingesting water is helpful for everything from clearing toxins and keeping organs healthy to warding off weight gain and improving skin tone.

To investigate the true benefits of drinking water, Dan Negoianu, MD, and Stanley Goldfarb, MD, of the Renal, Electrolyte, and Hypertension Division at the University of Pennsylvania, in Philadelphia, PA, reviewed the published clinical studies on the topic. They found solid evidence that individuals in hot, dry climates, as well as athletes, have an increased need for water. In addition, people with certain diseases benefit from increased fluid intake. But no such data exist for average, healthy individuals. In addition, no single study indicates that people need to drink the recommended “8x8” amount of water each day. Indeed, it is unclear where this recommendation came from.

This scan of the literature included a look at studies related to the notion that increased water intake improves kidney function and helps to clear toxins. A variety of studies reveal that drinking water does have an impact on clearance of various substances by the kidney, including sodium and urea. However, these studies do not indicate any sort of clinical benefit that might result.

I've tried telling co-workers that their water habits were just the stuff of urban legends. But they were thoroughly wedded to their legends and kept on drinking. So just where did this urban legend originate? Maybe in some diet (wash that fat away) for losing weight? Or as part of some 1960s or 1970s fad about body detoxing?

Share |      Randall Parker, 2008 April 02 10:11 PM  Aging Diet Studies

Innovation Catalyst said at April 3, 2008 7:19 AM:

Are your friends thin? There's the benefit - and the only claimed benefit that I'm aware of. It helps dieters.

Rahein said at April 3, 2008 7:44 AM:

I have always though the 8x8 rule was an urban legend.

High levels of water consumption is required for good health though. Almost all reactions in your body take place in water and you need water to get water soluble chemicals out.

BBM said at April 3, 2008 8:48 AM:

8x8 is a ledgend, yes.

However, the majority of my patients drink too little. This is a problem especially in the south, and I think it contributes to a high rate of severe (surgical) constipation here.

I usually recommend 3-4 "tall" glasses of water (or other non-caffeinated beverage).

David Govett said at April 3, 2008 10:55 AM:

The human body does not always tell one how much water is needed. Many's the time I became symptomatically dehydrated while backpacking. My body never bothered to tell me I was thirsty.

GrannyJ said at April 3, 2008 11:07 AM:

You'll have to search much further back than the 60s, guys. I recall the 8x8 business back when I was a kid in the 30s.

N.Succorso said at April 3, 2008 1:28 PM:

Thirst signals are a lot less clear than hunger signals, and I chronically under-hydrate. Anecdotally, drinking at least 1750ml of water a day makes my weight loss progress far better than when I don't have a clear target. Granted, it's quite possibly just a follow-on effect -- if I'm tracking my water consumption, I'm likely also tracking my food consumption and exercise more closely than I would otherwise, which is likely to help me meet those daily goals -- but it helps, and I'm less concerned with whether that help is physiologically or psychologically mediated than I am with the actual results.

Rowdy Shoddy Piper said at April 9, 2008 12:27 AM:

Probably started by a soft drink company that started buying up spring water in the 1990s... but that's just idle speculation.

BB said at May 7, 2009 4:05 PM:

I lived in the desert (Las Vegas) for over twenty five years, so I have more than just a passing acquaintance with dehydration. Here's some anecdotal support for drinking water beyond quenching occasional thirst.

1. During the eight or so hours of sleep, the body expires about 6 to 8 oz. of water during respiration alone. So a big glass first thing in the morning will wake you up as fast as that cup of coffee.
2. Unless you are experiencing a medical problem, the kidneys do excrete a reduced amount of water during the night, so add another loss of 6 to 8 oz of water loss from urine in the morning.
3. Dehydration causes drowsiness during the waking hours, so back to that cup of coffee again (well, you get the picture). In the afternoon, drink a glass of water instead of heading for the snack machine.
4. An obstetrician will tell a patient to drink volumes of water to reduce false labor contractions. Water is a natural tranquilizer, so if you feel tense and/or irritable, go get a glass. It won't make you drowsy, just calm.
5. An eight oz. glass of water every 4 to 5 waking hours is better than gulping a glass an hour. Now notice I haven't addressed perspiration, but factor it in, say 4 oz a day.
6. So let's add this up: 8 plus 8 plus 8 plus 8 plus 4= 36 oz of water a day.

As far as weight loss is concerned, considering many of us eat or drink sugary things to fend off the drowsies, there may be something to weight loss and drinking water. Weight loss aside, there seems to be plenty of other reasons for deliberate water consumption rather than not.

bn sharma said at September 20, 2010 3:40 AM:

I drink 1.5 liter of water empty stomach in the morning.
Is is a good or bad practice

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