http://www.sciencedaily.com/print/2002/08/020809071640.htm
Reprinted from ScienceDaily Magazine ...
Source: Dartmouth Medical School
Date Posted: Friday, August 09, 2002
Web Address: http://www.sciencedaily.com/releases/2002/08/020809071640.htm
"Drink At Least 8 Glasses Of Water A Day" -- Really?
Hanover, NH -- It has become accepted wisdom: "Drink at least eight glasses of water a day!" Not necessarily, says a DMS
physician Heinz Valtin, MD. The universal advice that has made guzzling water a national pastime is more urban myth than
medical dogma and appears to lack scientific proof, he found.
In an invited review published online by the American Journal of Physiology August 8, Valtin, professor emeritus of physiology at
Dartmouth Medical School, reports no supporting evidence to back this popular counsel, commonly known as "8 x 8" (for eight,
eight-ounce glasses). The review will also appear in a later issue of the journal.
Valtin, a kidney specialist and author of two widely used textbooks on the kidney and water balance, sought to find the origin of
this dictum and to examine the scientific evidence, if any, that might support it. He observes that we see the exhortation
everywhere: from health writers, nutritionists, even physicians. Valtin doubts its validity. Indeed, he finds it, "difficult to believe that
evolution left us with a chronic water deficit that needs to be compensated by forcing a high fluid intake."
The 8 x 8 rule is slavishly followed. Everywhere, people carry bottles of water, constantly sipping from them; it is acceptable to
drink water anywhere, anytime. A pamphlet distributed at one southern California university even counsels its students to "carry a
water bottle with you. Drink often while sitting in class..."
How did the obsession start? Is there any scientific evidence that supports the recommendation? Does the habit promote good
health? Might it be harmful?
Valtin thinks the notion may have started when the Food and Nutrition Board of the National Research Council recommended
approximately "1 milliliter of water for each calorie of food," which would amount to roughly two to two-and-a-half quarts per day
(64 to 80 ounces). Although in its next sentence, the Board stated "most of this quantity is contained in prepared foods," that last
sentence may have been missed, so that the recommendation was erroneously interpreted as how much water one should drink
each day.
He found no scientific studies in support of 8 x 8. Rather, surveys of fluid intake on healthy adults of both genders, published as
peer-reviewed documents, strongly suggest that such large amounts are not needed. His conclusion is supported by published
studies showing that caffeinated drinks, such as most coffee, tea and soft drinks, may indeed be counted toward the daily total. He
also points to the quantity of published experiments that attest to the capability of the human body for maintaining proper water
balance.
Valtin emphasizes that his conclusion is limited to healthy adults in a temperate climate leading a largely sedentary existence --
precisely, he points out, the population and conditions that the "at least" in 8 x 8 refers to. At the same time, he stresses that large
intakes of fluid, equal to and greater than 8 x 8, are advisable for the treatment or prevention of some diseases, such as kidney
stones, as well as under special circumstances, such as strenuous physical activity, long airplane flights or hot weather. But barring
those exceptions, he concludes that we are currently drinking enough and possibly even more than enough.
Despite the dearth of compelling evidence, then, What's the harm? "The fact is that, potentially, there is harm even in water,"
explains Valtin. Even modest increases in fluid intake can result in "water intoxication" if one's kidneys are unable to excrete
enough water (urine). Such instances are not unheard of, and they have led to mental confusion and even death in athletes, in
teenagers after ingesting the recreational drug Ecstasy, and in ordinary patients.
And he lists other disadvantages of a high water intake: (a) possible exposure to pollutants, especially if sustained over many
years; (b) frequent urination, which can be both inconvenient and embarrassing; (c) expense, for those who satisfy the 8 x 8
requirements with bottled water; and (d) feelings of guilt for not achieving 8 x 8.
Other claims discredited by scientific evidence that Valtin discusses include:
Thirst Is Too Late. It is often stated that by the time people are thirsty, they are already dehydrated. On the contrary, thirst begins
when the concentration of blood (an accurate indicator of our state of hydration) has risen by less than two percent, whereas most
experts would define dehydration as beginning when that concentration has risen by at least five percent.
Dark Urine Means Dehydration. At normal urinary volume and color, the concentration of the blood is within the normal range and
nowhere near the values that are seen in meaningful dehydration. Therefore, the warning that dark urine reflects dehydration is
alarmist and false in most instances. Is there scientific documentation that we do not need to drink "8 x 8"? There is highly
suggestive evidence, says Valtin. First is the voluminous scientific literature on the efficacy of the osmoregulatory system that
maintains water balance through the antidiuretic hormone and thirst. Second, published surveys document that the mean daily fluid
intake of thousands of presumably healthy humans is less than the roughly two quarts prescribed by 8 x 8. Valtin argues that, in
view of this evidence, the burden of proof that everyone needs 8 x 8 should fall on those who persist in advocating the high fluid
intake without, apparently, citing any scientific support.
Finally, strong evidence now indicates that not all of the prescribed fluid need be in the form of water. Careful peer-reviewed
experiments have shown that caffeinated drinks should indeed count toward the daily fluid intake in the vast majority of persons.
To a lesser extent, the same probably can be said for dilute alcoholic beverages, such as beer, if taken in moderation.
"Thus, I have found no scientific proof that absolutely every person must 'drink at least eight glasses of water a day'," says Valtin.
While there is some evidence that the risk of certain diseases can be lowered by high water intake, the quantities needed for this
beneficial effect may be less than 8 x 8, and the recommendation can be limited to those particularly susceptible to the diseases in
question.
DMS news is on the web at http://www.dartmouth.edu/dms/news.
***************
http://www.miami.com/mld/miamiherald/living/columnists/dave_barry/3788338.htm?template=contentModules/printstory.jsp
Posted on Sun, Aug. 04, 2002
Water everywhere and not a drop to drink (for free)
DAVE BARRY
Gatorade is now making water. I know this because I saw a Gatorade commercial that asks the intriguing
question: ''What if Gatorade made water?''
(Intriguing answer: Gatorade will charge you a dollar for a small bottle of it.)
The commercial features the usual cast of hyperactive Gatorade people, who have to constantly ingest
massive quantities of fluids, or they shrivel up like dead toads on hot asphalt. Gatorade people dehydrate
rapidly because they are fanatically dedicated to exercise, and as a result, perspiration-wise, they are human
fire hydrants.
Even when they stand still, sweat gushes from their every pore, so that within seconds they're surrounded by
an expanding puddle of their own bodily secretions. People are constantly slipping and falling around them, but
the Gatorade people don't notice. That's how dedicated they are.
The Gatorade people are similar to the Nike-commercial people, another group of fierce, focused, grunting
competitors who give a minimum of 175 percent and would not hesitate to elbow their own grandmother in the
teeth if she stood between them and their objective (usually, a ball). The message of these commercials is that
Nike people are winners, because they have heart, willpower, and the one ''intangible'' asset that all true
champions possess: severely overpriced sneakers.
Here's an intriguing question: What if a Gatorade man married a Nike woman? THAT would be a competitive
wedding. The happy couple would race each other down the aisle, the bride gaining a momentary advantage by
jamming her bridal bouquet into the groom's eye, then the groom countering by stomping on her bridal train,
snapping her head back like a Pez dispenser, while the guests cheered and jumped up and down in their sweat
puddles. At the reception, everybody would eat a wedding cake made entirely out of Power Bars, and take
turns bench-pressing members of the band. Blood would be shed during the limbo competition.
But getting back to my point: Gatorade is now making water. It joins the rapidly growing list of companies,
including Coke, Pepsi and (any day now) Yoo-Hoo, getting into the highly profitable, multi-billion-dollar business
of making water.
Of course, when I say that these companies ''make'' water, what I mean is that they ''do not make'' water.
There's no need to actually MAKE water, because there's already water all over the planet -- water in lakes,
water in rivers, water falling from the sky, water in your home plumbing system, water escaping from your home
plumbing system causing your ceiling to collapse when you're away on vacation, water just EVERYWHERE.
What the bottled-water companies do is get some of this water, put it in bottles, give it a brand name, sell it
to consumers, then smack themselves in their corporate foreheads and say, ''We can't BELIEVE we're getting
away with this! Do you think they'd buy air? How about dirt?''
Incredible as it may seem, there was a time, years ago, when people right here in America actually drank the
water that came out of their taps. Back then, if you had tried to ''brand'' water and sell it, people would have
laughed and squirted you with garden hoses.
Today, of course, thanks to the educational efforts of the bottled-water industry, we consumers are terrified
of our tap water, because we know that it contains some of the most deadly substances known to man:
chemicals. To cite one example: Bottled-water-industry researchers recently issued an alarming report stating
that virtually every sample of tap water they tested contained large quantities of hydrogen, which is a type of
atom believed to have caused the Hindenburg dirigible disaster.
''We're not saying that people who drink tap water will explode in massive fireballs,'' assured the researchers.
''We're just saying they should avoid open flames.''
This is why millions of consumers now prefer bottled water, which -- we know this, because we have seen it
with our own eyes, in commercials -- bubbles up from pristine underground mountain springs, and thus does not
contain any impurities, unless of course you count worm droppings.
I mean, let's face it, underground is where worms live, and very few worm species wear diapers. Also, your
mountains are frequented by your mountain goats, which drink from the springs, and if you know anything
about goats, you know they drool. ''He drools like a goat'' is a common mountain expression.
But big deal, bottled-water consumers! Ingesting goat saliva and worm poop (which is very low in fat) is a small
price to pay for the security of knowing you are drinking water that is backed by the highest scientific quality
of marketing campaign, right? So let's raise our glasses of brand-name water in a toast to health and fitness!
OK, you Gatorade people, please put your arms back down.
Reprinted from ScienceDaily Magazine ...
Source: Dartmouth Medical School
Date Posted: Friday, August 09, 2002
Web Address: http://www.sciencedaily.com/releases/2002/08/020809071640.htm
"Drink At Least 8 Glasses Of Water A Day" -- Really?
Hanover, NH -- It has become accepted wisdom: "Drink at least eight glasses of water a day!" Not necessarily, says a DMS
physician Heinz Valtin, MD. The universal advice that has made guzzling water a national pastime is more urban myth than
medical dogma and appears to lack scientific proof, he found.
In an invited review published online by the American Journal of Physiology August 8, Valtin, professor emeritus of physiology at
Dartmouth Medical School, reports no supporting evidence to back this popular counsel, commonly known as "8 x 8" (for eight,
eight-ounce glasses). The review will also appear in a later issue of the journal.
Valtin, a kidney specialist and author of two widely used textbooks on the kidney and water balance, sought to find the origin of
this dictum and to examine the scientific evidence, if any, that might support it. He observes that we see the exhortation
everywhere: from health writers, nutritionists, even physicians. Valtin doubts its validity. Indeed, he finds it, "difficult to believe that
evolution left us with a chronic water deficit that needs to be compensated by forcing a high fluid intake."
The 8 x 8 rule is slavishly followed. Everywhere, people carry bottles of water, constantly sipping from them; it is acceptable to
drink water anywhere, anytime. A pamphlet distributed at one southern California university even counsels its students to "carry a
water bottle with you. Drink often while sitting in class..."
How did the obsession start? Is there any scientific evidence that supports the recommendation? Does the habit promote good
health? Might it be harmful?
Valtin thinks the notion may have started when the Food and Nutrition Board of the National Research Council recommended
approximately "1 milliliter of water for each calorie of food," which would amount to roughly two to two-and-a-half quarts per day
(64 to 80 ounces). Although in its next sentence, the Board stated "most of this quantity is contained in prepared foods," that last
sentence may have been missed, so that the recommendation was erroneously interpreted as how much water one should drink
each day.
He found no scientific studies in support of 8 x 8. Rather, surveys of fluid intake on healthy adults of both genders, published as
peer-reviewed documents, strongly suggest that such large amounts are not needed. His conclusion is supported by published
studies showing that caffeinated drinks, such as most coffee, tea and soft drinks, may indeed be counted toward the daily total. He
also points to the quantity of published experiments that attest to the capability of the human body for maintaining proper water
balance.
Valtin emphasizes that his conclusion is limited to healthy adults in a temperate climate leading a largely sedentary existence --
precisely, he points out, the population and conditions that the "at least" in 8 x 8 refers to. At the same time, he stresses that large
intakes of fluid, equal to and greater than 8 x 8, are advisable for the treatment or prevention of some diseases, such as kidney
stones, as well as under special circumstances, such as strenuous physical activity, long airplane flights or hot weather. But barring
those exceptions, he concludes that we are currently drinking enough and possibly even more than enough.
Despite the dearth of compelling evidence, then, What's the harm? "The fact is that, potentially, there is harm even in water,"
explains Valtin. Even modest increases in fluid intake can result in "water intoxication" if one's kidneys are unable to excrete
enough water (urine). Such instances are not unheard of, and they have led to mental confusion and even death in athletes, in
teenagers after ingesting the recreational drug Ecstasy, and in ordinary patients.
And he lists other disadvantages of a high water intake: (a) possible exposure to pollutants, especially if sustained over many
years; (b) frequent urination, which can be both inconvenient and embarrassing; (c) expense, for those who satisfy the 8 x 8
requirements with bottled water; and (d) feelings of guilt for not achieving 8 x 8.
Other claims discredited by scientific evidence that Valtin discusses include:
Thirst Is Too Late. It is often stated that by the time people are thirsty, they are already dehydrated. On the contrary, thirst begins
when the concentration of blood (an accurate indicator of our state of hydration) has risen by less than two percent, whereas most
experts would define dehydration as beginning when that concentration has risen by at least five percent.
Dark Urine Means Dehydration. At normal urinary volume and color, the concentration of the blood is within the normal range and
nowhere near the values that are seen in meaningful dehydration. Therefore, the warning that dark urine reflects dehydration is
alarmist and false in most instances. Is there scientific documentation that we do not need to drink "8 x 8"? There is highly
suggestive evidence, says Valtin. First is the voluminous scientific literature on the efficacy of the osmoregulatory system that
maintains water balance through the antidiuretic hormone and thirst. Second, published surveys document that the mean daily fluid
intake of thousands of presumably healthy humans is less than the roughly two quarts prescribed by 8 x 8. Valtin argues that, in
view of this evidence, the burden of proof that everyone needs 8 x 8 should fall on those who persist in advocating the high fluid
intake without, apparently, citing any scientific support.
Finally, strong evidence now indicates that not all of the prescribed fluid need be in the form of water. Careful peer-reviewed
experiments have shown that caffeinated drinks should indeed count toward the daily fluid intake in the vast majority of persons.
To a lesser extent, the same probably can be said for dilute alcoholic beverages, such as beer, if taken in moderation.
"Thus, I have found no scientific proof that absolutely every person must 'drink at least eight glasses of water a day'," says Valtin.
While there is some evidence that the risk of certain diseases can be lowered by high water intake, the quantities needed for this
beneficial effect may be less than 8 x 8, and the recommendation can be limited to those particularly susceptible to the diseases in
question.
DMS news is on the web at http://www.dartmouth.edu/dms/news.
***************
http://www.miami.com/mld/miamiherald/living/columnists/dave_barry/3788338.htm?template=contentModules/printstory.jsp
Posted on Sun, Aug. 04, 2002
Water everywhere and not a drop to drink (for free)
DAVE BARRY
Gatorade is now making water. I know this because I saw a Gatorade commercial that asks the intriguing
question: ''What if Gatorade made water?''
(Intriguing answer: Gatorade will charge you a dollar for a small bottle of it.)
The commercial features the usual cast of hyperactive Gatorade people, who have to constantly ingest
massive quantities of fluids, or they shrivel up like dead toads on hot asphalt. Gatorade people dehydrate
rapidly because they are fanatically dedicated to exercise, and as a result, perspiration-wise, they are human
fire hydrants.
Even when they stand still, sweat gushes from their every pore, so that within seconds they're surrounded by
an expanding puddle of their own bodily secretions. People are constantly slipping and falling around them, but
the Gatorade people don't notice. That's how dedicated they are.
The Gatorade people are similar to the Nike-commercial people, another group of fierce, focused, grunting
competitors who give a minimum of 175 percent and would not hesitate to elbow their own grandmother in the
teeth if she stood between them and their objective (usually, a ball). The message of these commercials is that
Nike people are winners, because they have heart, willpower, and the one ''intangible'' asset that all true
champions possess: severely overpriced sneakers.
Here's an intriguing question: What if a Gatorade man married a Nike woman? THAT would be a competitive
wedding. The happy couple would race each other down the aisle, the bride gaining a momentary advantage by
jamming her bridal bouquet into the groom's eye, then the groom countering by stomping on her bridal train,
snapping her head back like a Pez dispenser, while the guests cheered and jumped up and down in their sweat
puddles. At the reception, everybody would eat a wedding cake made entirely out of Power Bars, and take
turns bench-pressing members of the band. Blood would be shed during the limbo competition.
But getting back to my point: Gatorade is now making water. It joins the rapidly growing list of companies,
including Coke, Pepsi and (any day now) Yoo-Hoo, getting into the highly profitable, multi-billion-dollar business
of making water.
Of course, when I say that these companies ''make'' water, what I mean is that they ''do not make'' water.
There's no need to actually MAKE water, because there's already water all over the planet -- water in lakes,
water in rivers, water falling from the sky, water in your home plumbing system, water escaping from your home
plumbing system causing your ceiling to collapse when you're away on vacation, water just EVERYWHERE.
What the bottled-water companies do is get some of this water, put it in bottles, give it a brand name, sell it
to consumers, then smack themselves in their corporate foreheads and say, ''We can't BELIEVE we're getting
away with this! Do you think they'd buy air? How about dirt?''
Incredible as it may seem, there was a time, years ago, when people right here in America actually drank the
water that came out of their taps. Back then, if you had tried to ''brand'' water and sell it, people would have
laughed and squirted you with garden hoses.
Today, of course, thanks to the educational efforts of the bottled-water industry, we consumers are terrified
of our tap water, because we know that it contains some of the most deadly substances known to man:
chemicals. To cite one example: Bottled-water-industry researchers recently issued an alarming report stating
that virtually every sample of tap water they tested contained large quantities of hydrogen, which is a type of
atom believed to have caused the Hindenburg dirigible disaster.
''We're not saying that people who drink tap water will explode in massive fireballs,'' assured the researchers.
''We're just saying they should avoid open flames.''
This is why millions of consumers now prefer bottled water, which -- we know this, because we have seen it
with our own eyes, in commercials -- bubbles up from pristine underground mountain springs, and thus does not
contain any impurities, unless of course you count worm droppings.
I mean, let's face it, underground is where worms live, and very few worm species wear diapers. Also, your
mountains are frequented by your mountain goats, which drink from the springs, and if you know anything
about goats, you know they drool. ''He drools like a goat'' is a common mountain expression.
But big deal, bottled-water consumers! Ingesting goat saliva and worm poop (which is very low in fat) is a small
price to pay for the security of knowing you are drinking water that is backed by the highest scientific quality
of marketing campaign, right? So let's raise our glasses of brand-name water in a toast to health and fitness!
OK, you Gatorade people, please put your arms back down.
THE END
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