Thread: Research debunks health value of guzzling water

Research debunks health value of guzzling water
Wed Apr 2, 2008 6:32pm EDT

WASHINGTON (Reuters) - The notion that guzzling glasses of water to flood yourself with good health is all wet, researchers said on Wednesday.

Dr. Stanley Goldfarb and Dr. Dan Negoianu of the University of Pennsylvania in Philadelphia reviewed the scientific literature on the health effects of drinking lots of water.

People in hot, dry climates and athletes have an increased need for water, and people with certain diseases do better with increased fluid intake, they found. But for average healthy people, more water does not seem to mean better health, they said.

Their scientific review, published in the Journal of the American Society of Nephrology, is the latest to undercut the recommendations advanced by some experts to drink eight glasses of 8 ounces (225 ml) of water a day.

Dr. Heinz Valtin of Dartmouth Medical School in 2002 also put those recommendations to the test, finding them to be more urban myth than medical dogma and lacking in scientific basis.

Goldfarb and Negoianu examined what Goldfarb called "four major myths" regarding claims of a benefit for extra water drinking: that it leads to more toxin excretion, improves skin tone, makes one less hungry and reduces headache frequency.

"Our bottom line was that there was no real good science -- or much science at all -- behind these claims, that they represent probably folklore," Goldfarb said.

As far as facilitating toxin excretion, Goldfarb said that was not verified by any sort of scientific study.

"The kidneys clear toxins. This is what the kidneys do. They do it very effectively. And they do it independently of how much water you take in. When you take in a lot of water, all you do is put out more urine but not more toxins in the urine," Goldfarb said.

No studies showed any benefit to skin tone as a result of increased water intake, they found. They also found evidence lacking that drinking water wards off headaches.

As far as lots of water serving to limit appetite, he said there was no consistent evidence, adding it was "a little unclear exactly whether that was true."

"What no one looked at is whether anyone really loses weight over the long haul if they go under this regimen of drinking lots of water," Goldfarb said. "We just expressed uncertainty in that area."

While it may not help a person to drink lots of water, it may not harm them much either, Goldfarb said.

"If someone enjoys it, I say that's wonderful, keep doing it. They're not doing anything that's going to hurt them."

"A little mild dehydration for the most part is OK, and a little mild water excess for the most part is OK. It's the extremes that one needs to avoid," he said.

(Editing by Maggie Fox and Peter Cooney)

http://www.reuters.com/article/healthNe ... 9720080402

No benefit in drinking eight glasses of water a day, scientists say
By Rebecca Smith, Medical Editor
Last Updated: 2:02am BST 03/04/2008

The idea that drinking eight glasses of water a day is good for your health has been dismissed as a myth.

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Scientists say there is no evidence drinking large amounts of water is beneficial for the average healthy person, and do not even know how this widely held belief came about.


Myth: Healthy people do not need eight 8oz glasses of water a day


Specialists in kidney conditions in America reviewed research on claims eight 8oz glasses of water help flush toxins from the body, preventing weight gain and improving skin tone.

Dr Dan Negoianu and Dr Stanley Goldfarb, of the Renal, Electrolyte and Hypertension Division at the University of Pennsylvania, said no single study indicated average healthy people needed to drink this amount of water - a total of 3.3 pints - each day.

"Indeed, it is unclear where this recommendation came from," they say in a review in the Journal of the American Society of Nephrology.

The researchers did find some evidence that individuals in hot, dry climates, as well as athletes, need to increase the amount of water they drink. Studies have also shown that drinking lots of water helps the body to clear salt and urea.

But no studies have found any benefit to the organs of increased water intake.

Drs Negoianu and Goldfarb also investigated the theory that drinking more water makes you feel full and curbs appetite.

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Proponents say this may help maintain a healthy weight and fight obesity, but the evidence for this claim remains inconclusive, states the review.

No carefully designed clinical trials have measured the effects of water intake on weight maintenance.

Headaches also are often attributed to water deprivation, but there is little data to back this up, claim the scientists.

Only one small trial has addressed this question, and while trial participants who increased their water intake experienced fewer headaches than those who did not, the results were not statistically significant.

In addition, water has been touted as an elixir for improved skin tone.

The authors said that while dehydration can decrease skin stiffness, no studies have shown any clinical benefit to skin tone as a result of increased water intake.

The literature review by Drs Negoianu and Goldfarb reveals there is no clear evidence of benefit from increasing water intake. On the other hand, no clear evidence exists of a lack of benefit. "There is simply a lack of evidence in general," they explain.

On average, the body uses between 1.7 and 2.6 pints (one-1.5 litres) of water daily and more in high temperatures or when exercising.

This is replaced through drinks but a large amount is also contained in food, so it is not necessary to drink an equivalent amount to replace water levels.

Too much water can affect the balance of salts in the body causing "water intoxication", which can be fatal.

http://www.telegraph.co.uk/news/main.jh ... lth103.xml

Lots of water 'is little benefit'

UK experts say research which finds drinking lots of water does little to improve health should not discourage people from topping up regularly.

A scientific review by the University of Pennsylvania said some people, such as athletes, may need to drink a lot.

But they found little evidence that flushing out toxins through drinking copious amounts improved health.

However, the Food Standards Agency is sticking to its recommendation to drink six to eight glasses of fluid a day.

There is no clear evidence of benefit from drinking increased amounts of water

University of Pennsylvania scientists

The body's natural systems normally keep us topped up with water by making us feel thirsty, but various arguments are used to justify drinking extra.

It has been claimed that it can help remove toxic chemicals from the body, stop headaches, make you eat less, and even keep your skin healthier.

Dr Dan Negoianu, and Dr Stanley Goldfarb, writing the the Journal of the American Society of Nephrology, say that while dehydration can be harmful, there is scant evidence that large amounts of water offer any benefits.

In fact, they said, there was no evidence supporting the standard US recommendation of "8x8" - eight glasses, each containing eight ounces of water (a total of 1.8litres), a day.

They wrote: "There is no clear evidence of benefit from drinking increased amounts of water.

"Although we wish we could demolish all of the urban myths found on the Internet regarding the benefits of supplemental water ingestion, we concede there is also no clear evidence of lack of benefit.

"In fact, there is simply a lack of evidence in general."

Looking at other scientific papers revealed that while drinking more water did effect the rate at which various substances were cleared by the kidney, there was no suggestion that this led to any actual health benefits.

Skin tone

While one small trial found that drinking more water appeared to lead to fewer headaches, they said these results were not statistically significant.

And while dehydration can change the appearance of skin, there were no studies which suggested any clinical benefit to skin tone from drinking more.

In the UK, recommendations vary, with the Food Standards Agency's "Eatwell" website advising the public to drink six to eight small glasses of fluid a day - equivalent to 1.2 litres.

A spokesman said this estimate was based purely on studies of the fluid lost each day by the body, rather than any purported health benefits.

"In temperate climates, such as the UK, the government advises that six to eightglasses of water - about 1.2 litres - or other fluids should be consumed every day to prevent dehydration.

"The average 70kg man has a total daily water excretion of 2.5 litres - 1.3 litres is received from ingested food and metabolic activity with the remaining 1.2 litres coming from drinking."

The British Nutrition Foundation opted for slightly more, encouraging people to take between 1.5 and two litres.

However, a spokesman said: "I'm not sure how much science there is behind any recommendation that people drink more than this, unless you are doing a lot of physical activity or sweating a lot."

http://news.bbc.co.uk/2/hi/health/7326437.stm