Thinking today has changed somewhat with regard to water intake.
Previously, coffee and soda were not counted as water intake, because
soda and coffee contain sodium/caffeine that can retain fluid (sodium)
and cause a fluid loss (caffeine). Research has shown that people that
regularly drink coffee and sodas do not experience the water loss/gain
as casual consumers of such beverages. Also, water intake should be
consistent with our environment and activities, and not a one size
?[S]ome nutritionists insist that half the country is walking around
dehydrated. We drink too much coffee, tea and sodas containing
caffeine, which prompts the body to lose water, they say; and when we
are dehydrated, we don't know enough to drink.?
?Regular coffee and tea drinkers become accustomed to caffeine and
lose little, if any, fluid. In a study published in the October issue
of the Journal of the American College of Nutrition, researchers at
the Center for Human Nutrition in Omaha measured how different
combinations of water, coffee and caffeinated sodas affected the
hydration status of 18 healthy adults who drink caffeinated beverages
"We found no significant differences at all," says nutritionist Ann
Grandjean, the study's lead author. "The purpose of the study was to
find out if caffeine is dehydrating in healthy people who are drinking
normal amounts of it. It is not."
The same goes for tea, juice, milk and caffeinated sodas: One glass
provides about the same amount of hydrating fluid as a glass of water.
The only common drinks that produce a net loss of fluids are those
containing alcohol ? and usually it takes more than one of those to
cause noticeable dehydration, doctors say.?
?In general, to remain healthy we need to take in enough water to
replace the amount we lose daily through excretion, perspiration, and
other bodily functions, but that amount can vary widely from person to
person, based upon a variety of factors such as age, physical
condition, activity level, and climate. The "8-10 glasses of water per
day" is a rule of thumb, not an absolute minimum, and not of all of
our water intake need come in the form of drinking water.
The origins of the 8-10 glasses per day figure remain elusive. As a
recent Los Angeles Times article on the subject reported:
Consider that first commandment of good health: Drink at least eight
8-ounce glasses of water a day. This unquestioned rule is itself a
question mark. Most nutritionists have no idea where it comes from. "I
can't even tell you that," says Barbara Rolls, a nutrition researcher
at Pennsylvania State University, "and I've written a book on water."
Some say the number was derived from fluid intake measurements taken
decades ago among hospital patients on IVs; others say it's less a
measure of what people need than a convenient reference point,
especially for those who are prone to dehydration, such as many
?The consensus seems to be that the average person loses ten cups
(where one cup = eight ounces) of fluid per day but also takes in four
cups of water from food, leaving a need to drink only six glasses to
make up the difference, a bit short of the recommended eight to ten
glasses per day. But according to the above-cited article, medical
experts don't agree that even that much water is necessary:
Kidney specialists do agree on one thing, however: that the 8-by-8
rule is a gross overestimate of any required minimum. To replace daily
losses of water, an average-sized adult with healthy kidneys sitting
in a temperate climate needs no more than one liter of fluid,
according to Jurgen Schnermann, a kidney physiologist at the National
Institutes of Health.
One liter is the equivalent of about four 8-ounce glasses. According
to most estimates, that's roughly the amount of water most Americans
get in solid food. In short, though doctors don't recommend it, many
of us could cover our bare-minimum daily water needs without drinking
anything during the day.?
?For healthy people, the universal, age-old advice has been to
drink at least eight 8-ounce glasses of fluid daily -- preferably in
the form of water and discounting beverages containing alcohol or
caffeine because of their diuretic effect.
However, the validity of that recommendation has been questioned after a recent
search failed to uncover scientific proof supporting this practice.
Indeed, results of food surveys show that thousands of men and women
habitually consume less than ?8 x?8? without suffering any adverse
effects, thanks to the precision and effectiveness of the body?s
osmoregulatory system that maintains fluid balance. The bottom line is
that healthy adults leading a mostly sedentary lifestyle in a
temperate climate?in other words, a large proportion of Americans?may
not need ?8 ??8? to maintain health.
What is supported by scientific evidence is that eight glasses of
fluid or more are recommended to treat or prevent some diseases (e.g.,
kidney stones, constipation) and for vigorous work and exercise,
especially in hot climates.
In addition, several published studies show that caffeine is not the
dehydrating culprit as is commonly believed. In fact, an analysis of
the scientific literature dealing with moderate caffeine consumption
(e.g., the equivalent of 1 to 4 cups of coffee/day) found:
? The body retains some fluid from caffeinated beverages.
? The mild diuresis seen with moderate caffeine consumption is similar to that of
water. Strictly speaking, large amounts of water are a diuretic
because they increase
? People who regularly consume caffeine develop a higher tolerance to its diuretic
? There is no proof that consuming caffeinated beverages causes a
fluid and electrolyte imbalance detrimental to health or interferes
with the ability to perform physical activity.
The conclusion is that caffeinated beverages can count toward the
day?s total fluid intake, providing that caffeine consumption is not
For healthy adults, thirst is usually a reliable indicator of water
need and fluid intake is assumed to be adequate when the color of
urine produced is pale yellow.
However, the sensation of thirst is blunted in the elderly, in
children, and during hot weather or strenuous exercise. For these
people and conditions, drinking fluids should not be delayed until the
sensation of thirst occurs because by then fluid loss is significant.
Because the body cannot store water, it should be consumed throughout
Here is the conclusion of a study in the Journal of American College
of Nutrition, supported by a grant from Coca-Cola, ?The Effect of
Caffeinated, Non-Caffeinated, Caloric and Non-Caloric Beverages on
Hydration?. The study was overseen by Ann C. Grandjean, EdD, FACN,
CNS, Kristin J. Reimers, RD, MS, Karen E. Bannick, MA, and Mary C.
Haven, MS, The Center for Human Nutrition, (A.C.G., K.J.R.), School of
Allied Health Professions, University of Nebraska Medical Center,
(M.C.H.), Omaha, Nebraska, Bannick Consulting, Isle, Minnesota
You?re right if you expect the study to find virtually no difference
between hydration values of water and carbonated beverages!
?Acknowledging the limitations of the study, results indicate that
consuming caffeinated beverages did not significantly alter hydration
status as measured by weight change. It is further concluded that
blood and urine indices are insensitive to slight fluctuations in
hydration status. Additional research is needed to verify the findings
of this study.
Without question, a metabolic ward setting would have added a greater
degree of control, but the intent was to ascertain results applicable
to free-living individuals. In future research on the effect of
beverages on hydration status, testing other commonly consumed
beverages would have merit. Because the biochemical variables used in
this study were not sensitive enough to mark small changes in
hydration status as measured by body weight, deliberate dehydration
may be necessary to assess biochemical indicators of hydration
?Eight 8-ounce glasses of water a day. Another approach to water
intake is the "8 x 8 rule" ? drink eight 8-ounce glasses of water a
day (about 1.9 liters). The rule could also be stated, "drink eight
8-ounce glasses of fluid a day," as all fluids count toward the daily
total. Though this approach isn't supported by scientific evidence,
many people use this basic rule as a guideline for how much water and
other fluids to drink.?
?You don't need to sip from your water bottle all day to satisfy your
fluid needs. Your diet, including the beverages you drink, can provide
a large portion of what you need. In an average adult diet, food
provides about 20 percent of total water intake. The remaining 80
percent comes from beverages of all kinds.
Fruits and vegetables ? besides being good sources of vitamins,
minerals and fiber ? contain lots of water. For example, oranges are
87 percent water, and cucumbers are 95 percent water. Milk, juice and
other beverages also have large amounts of water. Conversely, dried
fruits, nuts, grain products and baked goods generally contain less
? Make it count: Meet your water needs through food and beverages
Alcohol ? such as beer and wine ? and caffeinated beverages ? such as
coffee, tea or soda ? can contribute to your total fluid intake. But
your best beverage is still water. Water is calorie-free, inexpensive
when drawn from a faucet or fountain, and readily available in and out
of your home.?
?Though uncommon, it's possible to drink too much water. Drinking
excessive amounts can overwhelm your kidneys' ability to get rid of
the water. This can lead to hyponatremia, a condition in which excess
water intake dilutes the normal amount of sodium in the blood.
Marathon runners and people who are older, who have certain medical
conditions ? such as congestive heart failure and cirrhosis, or who
are taking certain diuretics are at higher risk of hyponatremia.?
?IF YOU DO NOT KEEP UP WITH LOSSES, nature has a sensing system in
place called thirst. Under almost all circumstances it works very
effectively to alert an individual when water losses have produced
even a minor degree of water deficiency. Thirst is first perceived in
the mouth but it is a highly complex function that involves a number
of hormones and brain functions, all of which serve to signal fluid
intake. And one need not worry if the fluid is not pure water--the
fluids humans consume are almost entirely composed of water. As soon
as a few extra ounces of fluid are consumed, the system rapidly and
efficiently eliminates any overage.?
?An AI for total water, which includes drinking water, other
beverages, and water in food, is based on the median total water
intake from U.S. food consumption survey data. For men ages 19 to 30
the Adequate Intake (AI) is 3.7 L/day; for women of the same age, the
AI is 2.7 L. Fluid (water and other beverages) accounts for
approximately 81% of usual total water intake, with the remaining 19%
coming from water in food.
Similar to AIs set for other nutrients, daily intakes below the AI may
not be harmful to healthy people because normal hydration is
maintained over a wide range of intakes. Intakes higher than the AI
are recommended for rigorous activity in hot climates.?
I know you already know about the calcium/phosphorus problem, but
it?s included here:
Of concern is the high intake of soft drinks, particularly
among children and adolescents, which has increased dramatically in
recent decades. A recent survey indicates the mean daily intake of
soft drinks is 12 oz/day?approximately 150 calories of sugar water.
The problem with the ever-growing use of soft drinks is that:
? Soft drinks are 100% empty calories that may increase the risk of
weight gain and obesity.
Studies indicate that when extra calories are consumed in liquid form, the body
does not compensate for those additional calories by eating less later
on as it tends to do when extra carbohydrate calories are consumed in
solid form. Liquid calories appear to lack satiety value and so are
major contributors to obesity. In children, one serving of soft drink
per day increases the risk of becoming overweight by 60% during the
course of 1 year.
? Although the mean intake is 12 ounces/day, an actual serving can be
much larger. For
instance, a king-sized soft drink at Burger King is 35 ounces,
slightly more than 1 quart and about 426 calories.
? Soft drinks that displace milk remove the primary source of calcium
in the typical American diet, increasing the risk of osteoporosis. Low
calcium intakes may also increase the risk of bone fractures among
children and adolescents.
? High soft drink consumption is associated with lower total diet
quality, not just because less milk is consumed, but also because
intake of 100% fruit juice may be less. High soft drink consumers tend
to have lower intakes of vitamin A, vitamin D, riboflavin, and
?Adequate hydration is a crucial part of health and even a small
water loss can impair both mental and physical function. The average
adult requires at least 2-3 litres of water a day (2). This
requirement increases if you exercise. Thirst is a poor measure of
dehydration. You become dehydrated long before you feel thirsty so
drink water continuously throughout the day. Being well hydrated
improves how you feel and perform. Alternatively, choose fruit teas
and herbal blends, and water flavored with a little fresh fruit juice.
The best measure of fluid balance is urine colour, this should be
clear and pale at all times. Dark yellow urine is an indicator of
dehydration. Some multivitamins may give the urine a bright yellow
This article can be purchased for $37.42 USD
This article reviews the literature on how important water is to the
world's elderly population. Background:
Water is a finite resource, so we must preserve the water that we
have. Physiological aspects and what water requirements our bodies
maintain sum up this essential nutrient for life. Dehydration is a
concern in the elderly.
Five strategies related to water intake can promote health: (1) assess
for symptoms which may indicate dehydration, (2) encourage ingestion
of fluids and foods to maintain an optimal fluid level, (3) be alert
to physical and clinical conditions affecting hydration in the
elderly, (4) consider environmental factors which may affect body
fluids, electrolytes and acid-base balance, and (5) encourage methods
to increase fluid consumption.?
This one sells for $30.00 USD
?It is understood that water is the most essential nutrient for life,
yet research elucidating the fine points of hydration and fluid needs
is still in its youth. Public recommendations based on scientific
evidence are not always translated by the media into useful and
Conclusion: Further research investigating the benefits of all fluids,
and water in particular, as beverages to meet hydration and health
needs will help clarify the controversies over how much water we
should drink every day. Health practitioners must further work to
assist patients with designing practical fluid intake strategies to
ensure adequate hydration.?
You may find this (free) article interesting:
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P.S. I agree wholeheartedly that the Geico commercial you mention is
irritating and annoying!
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