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In this edition of McCurtain Memorial
Hospital’s nutrition newsletter, we will
explore the role of fluid and electrolytes in
keeping the body properly hydrated and
maintaining the function of muscles and
nerves.
What Does Water Do?
We all know that food and water are
essential to survival. But did you know that
while a person can survive for literally
weeks without food, we can only live about
2-3 days without fluid?!
Water is a critical nutrient for health and is
involved in many body processes:
● fluid balance ● nutrient transport
● nerve impulses ● removal of wastes
● muscle contraction ● chemical reactions
● and many more!
Water… be impressed!
Water is a type of body fluid. Fluids are
composed of freely moving molecules with
the ability to conform to the shape of
whatever container holds them. The type
and composition of our body fluid is very
important.
Nutrients in Fluid and Electrolyte Balance
Food and Nutrition Services
The Role of Nutrition on Our Health
Inside:
Body Composition and
Body Fluid
1-2
Functions of Fluids and
Electrolytes
3-4
Maintaining Fluid
Balance
5
Loss of Fluids and
Diuretics
6
Primary Electrolyte
Functions
7
Fluid Disorders 8
Additional Resources 9
Body Composition
It is true that a majority of our body is made up of
fluid. Depending on age, about 50-70% of our body
composition is basically water! For example, a 150
pound person is 90 pounds fluid, 30 pounds fat, 30
pounds carbohydrates, protein, and bone, and about a
pound of vitamins and minerals.
The human body is composed of billions of cells.
Each and every one of those cells is filled with fluid.
Thus, two-thirds of our body fluid is within the cells
and called intracellular fluid. The remaining
one-third of fluid surrounds or is outside the cells and
is called extracellular fluid.
Water is essential for a healthy body
and a long life. Drink up!
www.mmhok.com
580.286.7623
What is Body Fluid?
If you have ever heard that “muscle weighs more than fat” it is because
muscle tissue has more fluid!
Fluid does all kinds of things in your
body. For starters, water dissolves and
carries or transports substances. Water is
involved in almost all of the chemical
reactions that take place inside our bodies
(that works out to be about 10,000,000
reactions per minute). The dissolved
materials, or solutes, can now travel
through the body via blood. These solutes
include ions, carbohydrates, amino acids,
vitamins, and minerals. Since fat does not
dissolve in water, fat molecules are
combined with proteins for transport in
the blood.
Page 2 The Role of Nutrition on Our Health
The types of tissues that
make up our bodies contain
fluid as well. Muscle
tissue is 70% fluid while
fat tissue is only 10-20%
fluid. If you have ever
heard that “muscle weighs
more than fat” it is because
it has more fluid!
Gender also impacts body
fluid. It is a biological fact
that most males have more
muscle mass while most
females have more fat
mass. Therefore, men have
more body fluid than
women.
Muscle tissue is also called
lean tissue. As we age, our
muscle mass or lean tissue
mass decreases thus, our
body fluid lessens. To
keep this from happening
(we want lean mass and
fluid), you should
continue/start an exercise
program.
Babies are mostly water
with about 75% of their
body mass being fluid.
This is because babies’
bodies are composed of
TRILLIONS of cells which
all contain water! It is vital
that babies remain properly
hydrated at all times so all
of their intra- and
extracellular spaces are full
of water!
Functions of Fluid
Body Fluid
Not surprisingly, body fluid is mostly plain old water. However, water by itself is
not enough to keep us going. We also need mineral salts. These substances are more
commonly called electrolytes. The four major electrolytes in body fluid are:
● Sodium (Na+) ● Potassium (K+) ● Chloride (Cl–) ● Phosphorus (HPO42–)
When dissolved, mineral salts separate and form ion particles which carry an
electrical charge. This charge stimulates nerves and causes our muscles to contract
and relax. Without electrolytes we would not be able to move and our heart (a
muscle) would stop beating!
Functions of Electrolytes
BLOOD VOLUME
Fluids account for blood
volume. Blood is made up
of different types of cells,
plasma (a fluid), and
water. Blood volume is the
fluid part of blood.
Increased blood volume
can cause blood pressure to
rise (hypertension). This
can lead to heart
disease and stroke.
Decreased blood volume
can cause low blood
pressure (hypotension)
which can make a person
feel tired, confused, dizzy,
and weak.
Electrolytes (sodium, potassium, chloride, phosphorus) help
regulate fluid balance. Our billions of cells are permeable to
water. Water can freely flow in and out of the cells into the
extra or intracellular space. The cells can’t control this movement
of water but, in a way, electrolytes can. Electrolytes can’t flow in
and out of the cells by themselves. They need help from certain
kinds of proteins. These proteins attach themselves to the cell and
act as tiny gatekeepers, opening and closing to allow passage of
the electrolytes. Water prefers that the concentration of
electrolytes in and outside of the cell be balanced. Therefore,
water follows electrolytes from areas of low concentration to areas
of high concentration. This is called osmosis.
ORGAN PROTECTION
Body fluids protect and lubricate our tissues. Here are just a few examples:
● Cerebrospinal fluid protects brain and spinal column ● Synovial fluid lubricats joints
● Pleural fluid allows lungs to safely expand as we breathe ● Tears lubricate eyes
● Amniotic fluid protects fetus in pregnant women
● Digestive secretions allow for easy passage of food through body- saliva, mucus, hydrochloric acid
Functions of Fluid
Page 3 The Role of Nutrition on Our Health
BODY TEMPERATURE
Fluid helps maintain our body temperature. Water has a high heat capacity. This
means that it takes quite a bit of external energy to change the temperature of water.
This is good for us because we want to maintain a constant body temperature. When
our body temperature begins to rise due to external energy (heat from the sun) or from
heat we produce while exercising, we begin to sweat.
Sweating releases heat and the evaporation of water from the skin cools both the skin
and blood. Basically, our bodies move heated blood from our core (organs and tissues)
outward to the skin and we sweat. Then, the cooled blood travels back to our core.
Functions of Electrolytes
Water follows electrolytes to balance the fluid to mineral salt ratio. It is like if you have ever had a deli
meat sandwich and a bag of potato chips. Chances are, that meal made you thirsty! It is because of all the
sodium. Your body was letting you know that the fluid to electrolyte ratio was unbalanced. You needed
more water to dilute the concentration of salt!
Maintaining this balance is very important. Illness with vomiting/diarrhea, progressive sweating, or
bleeding can alter your fluid to electrolyte ratio and thus change the composition of your body cells– this
can be fatal.
(a). Ideally, your fluid and electrolyte balance is about equal both inside and outside of each body cell.
(b). Hypoatremia (low blood sodium), heart disease, liver or kidney failure, pneumonia, polydispia
(over-hydration), or intense exercise over many hours can cause the electrolyte concentration inside the cells
to be greater than outside the cell. Because water follows the higher concentration of electrolytes, water will
flow inside the cells to dilute the mineral salt concentration. This causes the cell to swell and potentially
burst, which kills the cell. This includes destroying our brain cells which can be fatal fairly rapidly.
(c). Hypertonic dehydration occurs when we lose fluid from our extracellular spaces. This can happen with
hyperventilation, diarrhea, fever or excessive sweating, improperly balanced tube or IV feeding solutions,
uncontrolled diabetes with ketoacidosis, or in diabetes insipidus (different than type 2 diabetes). Because
we have lost fluid from outside the cell, the mineral salt concentration increases. In other words, it is very
salty outside the cells. To compensate and dilute the salts, water flows out of our cells. This causes cells to
shrink. If balance is not restored quickly, this will cause the cell to shrivel and die.
Page 4 The Role of Nutrition on Our Health
Functions of Electrolytes
Electrolytes are ions that carry an electrical charge which help
nerves respond to stimuli. As electrolytes enter and exit the cell,
the charge of the cell changes thus creating an action potential or
signal that travels to the brain. Electrolytes are constantly moving
which allows us to do everything from breathing, to blinking, to
waving at a friend across the room!
Water lost from the body must be replaced… every day. We lose most of our water in urine and feces, through
sweat, and through respiration (breathing). We gain water by drinking fluid, eating food, and through internal
metabolic processes. Our body can even tell us when we need to add water. When you feel thirsty or if your throat is
dry, this is your body’s thirst mechanism at work. This is your cue to take a break and drink some water.
It is important to note that this mechanism has a major flaw. As we age, out thirst mechanism does not work very
well and many elderly people become dangerously dehydrated. It is important to drink fluids (especially water)
throughout the day even if you do not feel thirsty. Water-rich foods, like fruits and vegetables, also are great and tasty
ways to stay hydrated. Think about all the water in a juicy orange or watermelon! Even relatively dry foods like
almonds are still about 5% water.
Adult bodies have the ability
to restrict urine output and
retain water. Babies’ kidneys
are not sophisticated enough
to retain fluid. Infants also do
not have the ability to regulate
their body temperature like
adult bodies can. It is vital
that infants are properly
hydrated all day and are
adequately protected from hot
and cold temperatures.
Maintaining Fluid Balance
Page 5 The Role of Nutrition on Our Health
Fluid Loss
We lose fluid in sensible (noticeable) and insensible (invisible) ways.
Sensible Insensible
Urine Feces
Sweat Mild perspiration
Blood loss Blood donation
Illness (vomit/diarrhea/runny nose) Breathing/Coughing
Sneezing Medication use
Internal bleeding
Proper Hydration
A relatively easy way to determine if you are properly hydrated is to look
(and smell) your urine.
• A properly hydrated person’s kidneys will flush out more water with waste
material resulting in a clear or very light colored urine that doesn’t smell.
• With minor dehydration, the kidneys do not have enough water to flush out
waste so the urine has a yellow color and a slight smell.
• In severe dehydration, the body does not have enough water to spare to help
flush out the kidneys. This causes the urine to be dark in color and mostly
made up of waste material and have a very strong smell.
We also have to take note of our environment to
fully understand how our body fluid might be
impacted.
High altitudes have less oxygen which requires
increased respiration and more fluid lost.
High temperatures may mean you lose more fluid by
sweating. Places with low humidity have less water
in the air and our sweat evaporates faster.
Even low temperatures can cause us to lose more
body fluid through hormonal changes.
Pregnant women’s bodies devote a lot of fluid to
the developing fetus. Women who are breastfeeding
also have increased fluid needs.
Loss of Fluids
Page 6 The Role of Nutrition on Our Health
DIURETICS
Diuretics are substances that increase urine output. These
work by overriding hormonal messages that tell the kidneys to
retain water in a moderately or severely dehydrated person.
Misuse of diuretics can be extremely dangerous– even deadly.
Some types of medications are
diuretics. Be sure you understand
what you are taking and if you need
to increase your water intake.
Weight-loss pills and
supplements may also contain
diuretics. In these cases, you are
losing “water weight” rather than
excess weight from fat– not an
optimal outcome. You want that
water!
Alcohol is also a diuretic. While all
fluids from orange juice to tea make
you pee, alcohol is classified as a
diuretic because it blocks hormonal
messages to the kidneys and drinking
this particular fluid can actually
cause dehydration. Drinking alcohol
in moderation is a good idea for
various reasons, avoiding
dehydration is just one of them!
If you are consuming any kind of diuretic, the urine color
chart on the previous page does NOT apply to you! Please
be aware you may need more fluid than your urine color
indicates.
Fluid Needs
Fluid needs vary based on age, gender, overall
health, activity level, and environmental conditions.
General fluid recommendations in a healthy adult:
Men aged 19-50: need 3.7 liters of fluid a day which is
about 15.5 cups or 124 ounces
• 13 cups should come from water and food
Women aged 19-50: need 2.7 liters of fluid a day which
is about 11.5 cups or 92 ounces
• 9 cups should come from water and food
The well know advice of drinking “eight 8 ounce
glasses of water a day” is really a pretty good place to
start. If your diet is
high in fruits and
vegetables which
contain lots of water,
you may not need to
drink as much fluid.
However, if you
sweat or are sick, you
can lose several cups
of water in just one
hour! Look at the
picture to the right to
help you understand
where our body water
comes from and how
it is used.
Woman on 2500 calorie diet
be aware you may need more fluid than your urine color
More on Electrolytes
Page 7 The Role of Nutrition on Our Health
The following table outlines some basic information on the four major electrolyte nutrients.
The typical American consumes plenty of sodium and chloride. Sodium chloride is another name for table salt! In
fact, many people over-consume sodium, chloride, and phosphorous. Phosphorus is abundant in meat and in soda. Try
to eat more potassium, a nutrient Americans tend to be lacking. An apple or a cup of yogurt contain phosphorus (and
fluid) and make a delicious healthy snack!
*AI = Adequate Intake– should consume about this much based on current research
*UL = Upper Limit– do not exceed this much as it may result in toxicity symptoms
*RDA = Recommended Dietary Allowance– optimal consumption level
How Much Water During Exercise?
DEHYDRATION
Dehydration occurs when water
loss exceeds water intake. This is
commonly due to exercise or
sweating and increased breathing
rate, although lack of proper diet
and fluids can contribute.
Dehydration severity is classified
by percent body water lost. Even
a small percentage of lost body
fluid results in weight loss and
can have significant health
consequences (see table below).
Weight you lose right after a workout is not fat– sorry. It is water weight that needs to be replaced. An easy way to
determine exactly how much water you lost during your workout is to weigh yourself immediately before and then right
after on the same scale. If you weighed 160 pounds before your routine and 158 pounds after, you lost an equivalent of 2
pounds of water. You need to drink enough water to make up that difference before you exercise again. A good rule of
thumb is for every 15 minutes of exercise, drink at least 4-6 ounces of water. That means downing at least a full glass (8
ounces) every half hour.
Should you be drinking Gatorade or a sports beverage with electrolytes? Probably not. The casual exerciser only
needs water. Any electrolytes lost in sweat can easily be replaced in the next few meals. Sports drinks also contain
sugar which adds to your daily calorie intake. It is counterproductive to workout to burn calories and consume refined
sugar calories at the same time! Save yourself the hassle and the money– drink water and eat a healthy snack before and
after each workout!
Disorders Related to Fluid and Electrolyte Imbalance
Page 8 The Role of Nutrition on Our Health
HEAT STROKE
Heat stroke occurs if the body’s
temperature regulation
mechanisms fail. This most often
occurs in hot, humid
environments. Symptoms include
rapid pulse, hot dry skin, and
weakness. Untreated, heat stroke
can be fatal. Do not exercise
heavily or remain outside in
extreme heat!
Even young people can suffer
from heat stroke. Every year,
student athletes, usually football
players, die from this condition.
MUSCLE DISORDERS
Electrolyte imbalances can result
in nervous system malfunction
which can lead to seizures or
muscle cramps.
Symptoms of an imbalance may
include hallucinations, blackouts,
flashbacks, severe seizing causing
loss of bowel control, and
dislocated joints. Depression,
confusion, psychosis, and
impaired brain function may also
point to a fluid and electrolyte
imbalance.
Page 9 The Role of Nutrition on Our Health
McCurtain Memorial Hospital was
originally established in 1954 and
exists to provide excellence in
healthcare. Our vision is to be the
healthcare provider of choice in our
region.
We are proud to be working for a healthier community. We understand that
actions speak louder than words and that is why we take our mission and
vision seriously. We are always striving to improve our services and we value
your feedback.
1301 E Lincoln Rd Idabel, OK 74745 Phone: 580.286.7623
NOTES:
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Resources: McCurtain Memorial Hospital: local phone: 580.286.7623
Toll free: 1800.867.1182
http://www.mmhok.com
McCurtain Memorial Wellness Center: Information on the hospital’s on-site gym and
wellness center.
Ken Moore, ATC/LAT, Director of Wellness and
Community Health
580-208-3179
Sports Drink Info: http://nutritionwonderland.com/2009/05/sports-
drinks-good-or-bad/
Abby Bridges, RD/LD, MS
