No Need to Guzzle All That Water, Expert Says
Fri Aug 9, 7:40 PM ET
By Maggie Fox, Health and Science Correspondent
WASHINGTON (Reuters) - Trying to do the "right" thing by
drinking eight full glasses of water a day may do little more
than make a person run to the bathroom, a researcher said on
Friday.
Newspaper articles, health and beauty magazines all advise
drinking at least 8 full glasses of water a day totaling 64
ounces for optimal health -- an approach called "8x8" by
proponents.
But Dr. Heinz Valtin of Dartmouth Medical School in New
Hampshire said there is no scientific evidence to back up this
advice, which has helped create a huge market for bottled
water.
"After 10 months of careful searching I have found no
scientific evidence that supports '8x8'," Valtin, who has written
textbooks on the subject of human water balance, said in a
telephone interview.
Writing in the American Journal of Physiology, Valtin, a
kidney specialist, said people forget that the food they eat also
contains some water.
The Food and Nutrition Board of the National Research Council
( news - web sites) has recommended that people take in about one
milliliter of water for each calorie of food eaten.
This adds up to two liters, or 74 fluid ounces on an average
2,000-calorie diet. But the National Research Council also noted
that much of this is already contained in food.
"I did 43 years of research on that system -- the
osmoregulatory system. That system is so precise and so fast that
I find it impossible to believe that evolution left us with a
chronic water deficit," Valtin said.
LOW ON FLUID
If a person gets low on fluid, the body compensates by
bringing fluid back out of the kidneys and by slowing the loss of
water through the skin, Valtin said. Thirst kicks in long before
dehydration starts, he added.
"It does it very quickly and very accurately and it does so in
minutes," Valtin said.
He said he and colleagues became concerned after seeing dozens
of newspaper and magazine articles urging people to sip water all
day. "I started talking to my colleagues and asking them 'Do you
know of any evidence for this?'. Invariably, they said, 'No I
think it's a myth'," Valtin said.
The journal asked him to review all the scientific studies he
could find and he concluded that someone misinformed has been
telling people to drink large amounts of water when most do not
need to.
"I am referring to healthy adults in a temperate climate
leading a largely sedentary existence," Valtin said. "Persons
with certain diseases must have large volumes of water -- kidney
stones are probably the most common example."
The rest can just drink enough to slake thirst -- and this
includes coffee, tea, and even beer -- despite their diuretic
effects, Valtin said.
He hopes people will be relieved of the guilt of not getting
enough water, and of the expense of buying bottled water to drink
throughout the day.
"There is also the possibility that if you drink a lot of
water that happens to be polluted then of course you get more
pollutants," Valtin said.
"Then there is the inconvenience of constant urination, the
embarrassment of having to go to the bathroom all the time," he
added.
And overdoses of water can cause water intoxication that can
lead to confusion and even death. Water intoxication is one
deadly effect of taking the drug Ecstasy, for instance, because
it makes people thirsty beyond their physical needs.
Paul Mason's rebuttal is below.
Dear Dr. Valtin:
I agree with your assessment that for HYDRATION consumers do
not necessarily need 2 liters of water per day. However, you have
failed to address the role played by minerals in water,
specifically MAGNESIUM.
Mg is the second most common mineral in water, after Calcium.
Mg in water is more bioavailable than Mg in food, because of
interference from dietary fat, fiber, competing minerals, etc.,
e.g.: http://www.mgwater.com/sabatier.shtml
Almost all Americans get less than the RDI of Mg. See the NAS
Report at:
http://www.mgwater.com/exhibitk.shtml
In the US, bottled water averages only 2.7 mg/liter -- but
world-wide, the average is 38 mg/L -- and outside the US, the
average is 45 mg/L. This is because at the inception of the FDA
in 1930, the FDA's first act was to destroy the American mineral
water industry in the mistaken beliefs that:
1. mineral water is "impure" -- an oxymoron.
2. only "commies" drink mineral water (apparently the FDA thought
all Europeans were commies, as Europeans commonly drank mineral
water)
Regarding global levels of Mg in water see:
http://www.pmgeiser.ch/cgi-bin/mineral?sort=mg
Please correct the incorrect information you have purveyed to
the public in recent press releases:
http://story.news.yahoo.com/news?tmpl=story&u=/nm/20020809/sc_nm/health_water_dc_3
(This article has expired. Same as first section above.)
Mg-deficiency may be causing 150,000 to 225,000 deaths per
annum in the US, and your inaccurate press releases will only
exacerbate the deficiencies. See:
http://www.mgwater.com/exhibitk.shtml
http://www.mgwater.com/epidem.shtml
http://www.mgwater.com/calcs.shtml
Sincerely,
Paul Mason, editor
Magnesium Web Site
www.MgWater.com
This page was first uploaded to The Magnesium Web Site on
August 13, 2002
http://www.mgwater.com/
Healthy Water
Association--USA