At the end of this lecture, the student should be able to: Identify four nutrients that function as electrolytes in our bodies. List three functions of water in our bodies. Describe how electrolytes assist in the regulation of healthful fluid balance. Define hyponatremia and identify factors that can cause this condition. Identify four symptoms of dehydration.

1. Lecture 9:
Nutrients
Involved In
Fluid And
Electrolyte
Balance
DR. SHARIFAH WAJIHAH
WAFA

2. Topic Learning Outcomes
• At the end of this lecture, the student should be able to:
1. Identify four nutrients that function as electrolytes in our bodies.
2. List three functions of water in our bodies.
3. Describe how electrolytes assist in the regulation of healthful fluid
balance.
4. Define hyponatremia and identify factors that can cause this
condition.
5. Identify four symptoms of dehydration.

3. Course Outline
• Why Is Water So Important?
• Functions of Water in the Body
• Water Balance
• Electrolytes Participate in Fluid Balance
• How Do Water and Sodium Affect Blood
Pressure?

4. Body Fluids
• Body fluid is the liquid portion of cells and
tissues
• Characterized by its ability to move freely and
changeably, adapting to the shape of the
container that holds it
• About 50−70% of healthy adult body weight

5. Body Fluids
• Intracelluar fluid: within the cell
– 2/3 of body fluid
• Extracellular fluid: outside the cell
– 1/3 of body fluid
– Interstitial fluid flows between cells that make up a
particular tissue or organ (muscle, liver)
– Intravascular fluid is the water in the blood and lymph
– Plasma transports blood cells within arteries, veins, and
capillaries
Intracellular and Extracellular
Fluid

7. Body Fluids
• Fluid composition of tissue varies by:
– Tissue type: lean tissues have higher fluid content
than fat tissues
– Gender: males have more lean tissue and
therefore more body fluid than females
– Age: decrease in body water results partly from
loss of lean tissue as people age

8. Electrolytes
• Dissolved substances that disassociate in solution
into electrically charged particles called ions
– Positive charge: sodium, potassium
– Negative charge: chloride, phosphorus
• Predominant electrolytes
– Extracellular fluid: potassium, phosphorus
– Intracellular fluid: sodium, chloride
Role of Electrolytes in Water
Balance

9. Functions of Water
• Medium for chemical reactions
• Participates in chemical reactions
• Distributes nutrients to cells
• Removes waste products from cells
• Lubricant for joints
• Moistens organs, GI tract, eyes, skin
• Maintains body temperature
• Maintains blood volume

10. Acid-base
balance
Chemical
reactions
Lubricant
Distribution of
nutrients
Temperature
regulation
Removal of waste
products
Component of
body fluids

11. 21
Water is the Main Constituent of the Body
74 pounds of water
(57%)
17 pounds of protein
(13%)
32 pounds of fat
(25%)
7 pounds of minerals
(5%)
1 pound of glycogen
(<1%)
105 pounds of water
(62%)
27 pounds of protein
(16%)
27 pounds of fat
(16%)
10 pounds of minerals
(6%)
1 pound of glycogen
(<1%)
Healthy Man (170 pounds) Healthy Woman (130 pounds)
© Digital Vision / Getty Images RF

12. Functions of Body Fluids
• Fluids dissolve and transport substances
– Water is an excellent solvent because it dissolves a
variety of substances
– Water-soluble substances are readily transported
in the bloodstream: amino acids, glucose,
vitamins, minerals, medications
– Fatty substances must be attached to or
surrounded by water-soluble proteins

13. Functions of Body Fluids
• Fluids account for blood volume
– Appropriate body fluid levels are essential for
maintaining healthful blood volume
– Blood pressure increases when blood volume rises
– High blood pressure (hypertension) is a risk factor
for heart disease and stroke
– Low blood pressure can cause people to feel tired,
confused, or dizzy
– Kidneys help to regulate blood volume and blood
pressure

14. Functions of Body Fluids
• Fluids account for blood volume
– Antidiuretic hormone (ADH) stimulates the kidneys
to reabsorb water, reducing urine
– Renin responds to decreased blood pressure
– Angiotensin II (vasoconstrictor) increases blood
pressure
– Aldosterone signals the kidneys to retain sodium
and chloride, thereby retaining water, increasing
blood pressure, and decreasing urine output

16. Functions of Body Fluids
• Fluids help maintain body temperature
– Body temperature must be within a safe range
– Water has a high capacity for heat, which means
that only sustained high heat can increase body
temperature
– Sweating releases heat as the evaporation of
water from the skin cools the skin and blood

18. Functions of Body Fluids
• Protect and lubricate tissues
– Cerebrospinal fluid protects the brain and spinal
cord
– Amniotic fluid protects the fetus
– Synovial fluid lubricates joints
– Tears cleanse and lubricate eyes
– Saliva moistens food for swallowing

19. Functions of Electrolytes
• Electrolytes help regulate fluid balance
– Cell membranes are permeable to water, but not
freely permeable to electrolytes
– Water moves by osmosis to areas where the
concentration of solute is high
– This action provides a means to control movement
of water into and out of the cells
– Osmotic pressure keeps electrolytes in solution
from drawing liquid toward them across a
semipermeable membrane

22. Functions of Electrolytes
• Electrolytes enable nerves to respond to
stimuli
– Nerve impulses are initiated at nerve cell
membranes in response to a change in electrical
charge across the membrane
– Depolarization—Action Potential—Repolarization
– Sodium and potassium ensure that nerve impulses
are generated, transmitted, and completed

24. Functions of Electrolytes
• Electrolytes signal muscles to contract
– Muscles are stimulated to contract in response to
stimulation of nerve cells
– Influx of calcium into the muscle from the
extracellular space stimulates contraction
– Muscles can relax after contraction once the
electrical signal is complete and calcium is
pumped out of the muscle cell

25. Fluid Balance
• Thirst mechanism (hypothalamus) prompts us
to drink when it is stimulated by
– Increased concentration of salt and other
dissolved substances in the blood
– A reduction in blood volume and blood pressure,
such as during profuse sweating, vomiting,
diarrhea, or low fluid intake
– Dry mouth and throat from reduced saliva
• ADH signals the kidneys to retain water

26. Fluid Balance
• Body gains fluids
– Water enters the body through beverages
– Some foods have very high water content
– Water from metabolic reactions contributes
10−14% of daily water need

27. Fluid Balance
• Sensible water loss
– Kidneys excrete water as urine
– Sweat during exercise or in hot environment
• Insensible water loss
– Skin (not sweating) or lungs during exhalation
• Significant loss
– Illness, injury, exercise, high altitude, pregnancy,
breastfeeding, diuretics

28. Intake
2,500 mL/day
Output
2,500 mL/day
Metabolic water
200 mL
Feces 200
mL
Expired air
300 mL
Cutaneous
transpiration
400 mL
Sweat 100 mL
Urine
1,500
mL
Drink
1,600 mL
Food
700 mL
Fluid Balance

29. Water
• Water
– Essential for life
– Amount needed varies with gender, age, body
size, health status, physical activity level,
environment
– Sources of drinking water: carbonated, mineral,
distilled, purified, tap, bottled
ABC Video Bottled Water

32. Water
• What happens if we drink too much water?
– Becoming overhydrated is rare
– Dilution of blood sodium concentration
• What happens if we don’t drink enough
water?
– Dehydration
– Leading cause of death around the world
Water Balance

33. Sodium (Na+)
• Table salt = sodium chloride = NaC
– 40% sodium
– 60% chloride
• 1 tsp of salt = 2,400 mg sodium

34. Sodium: Functions
• Adds flavor to foods
• Preserves food
• Helps maintain fluid balance
• Helps nerve impulse
conduction
• Helps absorption of some
nutrients (ex: glucose)

35. Sodium: Deficiency
• Groups at risk:
– Low sodium diet
– Excessive sweating
(ex: athletes)
– Persistent vomiting or
diarrhea
• Symptoms:
– Muscle cramps
– Nausea and vomiting
– Dizziness
– Shock
– Coma

36. Sodium: Nutrient Needs
• DRI:
– For adults under age 51: 1,300 mg/day
– For adults aged 51-70: 1,300 mg/day
– For adults aged 71+: 1,200 mg/day
• Average American consumption:
– 2,300-4,700 mg/day
• DV on food labels based on:
– 2,400 mg/day
• To lower blood pressure:
– 2,000 mg/day or less

37. Sodium Intake
• AI: 1,500 mg
• most recommend < 2,300
mg/day
• <1,500 mg per day:
– Those with hypertension,
diabetes or chronic kidney
disease
• The National Heart Lung and
Blood Association reports that
500 mg is a safe daily minimum
intake of sodium

38. Food Sources of Sodium
• High sodium foods:
– Packaged foods
– Processed foods
– Fast food
– Canned foods
– Frozen, ready
prepared foods (ex:
pizza)
• Low sodium foods:
– Fruits & vegetables
– Whole grains
– Meats w/o sauces
– Unprocessed foods

39. Food Sources of Sodium
* For adults; see the DRI table in the back of this book for
age-specific recommendations.
Dairy
Key:
Adult Male and Female
AI = 1500 milligrams
Daily Value = 2400 milligrams
%AI
Food Item
and Amount
Sodium
Content
(milligrams)
ChooseMyPlate.gov
AI* 1500 100%
Pepperoni pizza , 2 slices 2045 136%
Ham, sliced, 1 ounce 1215 81%
Chicken noodle
soup, canned, 1 cup 1106 74%
V8 vegetable juice, 8 ounces 620 41%
Macaroni salad, ½ cup 561 37%
Hard pretzels, 1 ounce 486 32%
Hamburger with bun, 1 each 474 32%
Green beans, canned, ½ cup 390 26%
Saltine crackers, 6 each 234 16%
Cheddar cheese, 1 ounce 176 12%
Peanut butter, 2 tablespoons 156 10% Grains
Nonfat milk, 1 cup 127 8% Vegetables
Seven-grain bread, 1 slice 126 Fruits
8%
Animal crackers, 1 ounce 112 7% Protein
Grape juice, 1 cup 10 1%

40. 77
%
6
%
5
%
Added to foods
during cooking
at home
Added to food at the
table
12%
Present in foods
naturally
Added to foods
during food
processing or in
restaurant meals
Sodium in food

41. Sodium: Excess
• ↑ urine output & can lead to dehydration
– Normal 5g excreted daily
– Hypertension decreases renin result in
upto 25g excreted daily
• ↑ blood pressure indicates high sodium
• UL: 2,300 mg/day
– Note that the DV (2,400 mg) is > UL
– Healthier goal: aim for the AI (1,500 mg)

42. Potassium
• Potassium
– Major positively charged electrolyte in the
intracellular fluid
– Together with sodium, maintains fluid balance and
regulates the contraction of muscles and
transmission of nerve impulses
– High potassium intake helps maintain a lower
blood pressure

43. Potassium (K): Functions
• Water Balance
• Nerve impulse transmission
• Principal positively charged
intracellular ion
• ↑ potassium intake can help ↓ BP

44. Potassium: Deficiency
• Can be caused from:
– Chronic diarrhea
– Vomiting
– Laxative abuse
– Alcohol abuse
– Eating disorders
– Very low calorie diets
• Symptoms include:
– Loss of appetite
– Muscle cramps
– Confusion
– Constipation
– Irregular heart beat

45. Potassium: Nutrient Needs
• AI for adults:
– 4,700 mg
• DV used on labels:
– 3,500 mg
• Typical North American consumption:
– 2,000-3,000 mg/day

46. Food Sources of Potassium
• Unprocessed foods
– Fruits
– Vegetables
– Milk
– Whole grains
– Dried beans
– meats
• Major contributors in
the diet include:
– Milk
– Potatoes
– Beef
– Coffee
– Tomatoes
– Orange juice

47. Food Sources of Potassium
* For adults; see the DRI table in the back of this book for
age-specific recommendations.
8%
Food Item
and
Amount
Potassium
(milligrams)
Adult Male and
Female AI = 4700
milligrams
Daily Value = 3500milligrams
%AI
AI* 4700 100%
Kidney beans, 1 cup 715 15%
Winter squash, ¾ cup 670 14%
Plain yogurt, 1 cup 570 12%
Orange juice, 1 cup 495 11%
Cantaloupe, 1 cup 495 11%
Lima beans, ½ cup 480 10%
Banana, 1 medium 470 10%
Zucchini, 1 cup 450 10%
Soybeans, ½ cup 440 9%
Artichoke, 1 medium 425 9%
Tomato juice, ¾ cup 400
ChooseMyPlate
9%
Key:
Grains
Pinto beans, ½ cup 400 9% Vegetables
Baked potato, 1 small 385 8% Fruits
Buttermilk, 1 cup 370 Dairy
Protein
Sirloin steak, 3 ounces 345 7%
.gov

48. MyPlate: Sources of Potassium
58
MyPlate:
Sources of PotassiumChooseMyPlate.go
v
Fruits
Vegetables
Protein
Grains
• Whole-
wheat
bread
• Whole-
grain
products
Vegetables
• Avocados
• Spinach
• Squash
• Potatoes
• Tomatoes
• Lettuce
• Lima beans
Fruits
• Pears
• Prunes
• Peaches
• Cantaloupes
• Bananas
Dairy
• Milk
• Yogurt
• Cottage cheese
• Ricotta cheese
Protein
• Meat
• Chicken
• Fish
• Shrimp
• Beans
Grains
Dairy
(tomatoes): © Brand X Pictures/PunchStock RF; (pears): © Corbis RF; (shrimp): © Comstock Images / Jupiterimages RF

49. Potassium: Excess
• Typical food intakes do not lead to
potassium toxicity in people with
healthy kidneys
• If kidney function is poor:
potassium builds up in blood,
inhibits heart function & ↓
heartbeat
• No Upper Level (UL) has been set

50. Chloride (Cl): Functions
• Primary negatively charged ion
in the extracellular fluid
• Functions:
– Component of stomach acid (HCl)
– Immune response
– Nerve function

51. Chloride: Deficiency
• Prolonged vomiting (ex:
bulimia or severe flu) can lead
to acid-base disturbance due
to large loss of stomach acid
• Deficiency is unlikely because
dietary salt intake is so high

52. Chloride: Nutrient Needs
• AI for chloride is 2,300
mg/day
• Based on 40:60 ratio of
sodium: chloride in salt:
(1,500 mg sodium: 2,300
mg chloride)
• DV used on food labels is
5,400 mg

53. Food Sources of Chloride
• Fruits & Vegetables
• Chlorinated water
• Salt (NaCl)

54. Chloride: Excess
• Plays a role in salt in
raising blood pressure
• UL is 3,600 mg/day
• Because of ↑ salt intake,
average North American
intake of chloride is also ↑

55. Phosphorus
• Functions of phosphorus:
– Major intracellular negatively charged electrolyte
– Required for fluid balance
– Critical role in bone formation
– Regulates biochemical reactions by activating or
deactivating enzymes (phosphorylation)
– Found in ATP, DNA, RNA, cell membranes
(phospholipids), and lipoproteins

56. Phosphorus
• Recommended intake
– RDA for phosphorus is 700 mg/day
• Sources of phosphorus
– Widespread in many foods
– High in protein foods (meat, milk, eggs)
– More readily absorbed from animal sources
– Phytic acid: plant storage form
– Soft drinks

58. Phosphorus
• What happens if you consume too much
phosphorus?
– High blood phosphorus can occur among people
with kidney disease or when taking too many
vitamin D supplements
– Causes muscle spasms, convulsions
• What if you don’t consume enough
phosphorus?
– Deficiencies of phosphorus are rare

59. Medical Disorders
• Disorders related to fluid and electrolyte
imbalance include:
– Dehydration
– Heatstroke
– Water intoxication
– Hypertension
– Neuromuscular disorders
– Obesity

61. Dehydration
• Dehydration occurs when fluid loss exceeds
fluid intake
• Commonly due to heavy exercise or high
environmental temperatures
• Elderly and infants are at increased risk

63. Heatstroke
• Heatstroke occurs from failure in the body’s
heat-regulating mechanisms
– Hot, humid environments
– Symptoms: rapid pulse, hot and dry skin, high
body temperature, loss of consciousness
– Fatal during exercise in extreme heat
– Stop exercising when feeling dizzy, light-headed,
disoriented, or nauseated

64. Water Intoxication
• Overhydration can occur but it is rare
• Kidneys retain too much water, causing
overhydration and hyponatremia
• Documented cases of deaths among college
students (hazing rituals)

65. Hypertension
• Hypertension: major chronic disease
characterized by high blood pressure
– Often without symptoms
– Increases a person’s risk of heart disease, stroke,
kidney disease
– Can reduce brain function, impair physical
mobility, and cause death
– Systolic pressure over 140 mm Hg
– Diastolic pressure over 90 mm Hg

66. Hypertension
• What causes hypertension?
–Primary (or essential) hypertension:
unknown cause for 90−95% of cases
–5−10% are caused by kidney disease, sleep
apnea, and chronic alcohol abuse
–Salt sensitivity: >50% adults with
hypertension

67. Hypertension
• Recommendations for reducing hypertension:
– Losing weight
– Increasing physical activity
– Reducing alcohol intake
– Reducing sodium intake
– Eating more whole grains, fruits, vegetables, and
low-fat dairy foods
– DASH diet

68. Hypertension
• Medications
– Help in normalizing blood pressure
– Should also continue to practice healthful lifestyle
changes
• Hypertension: “the silent killer”
– Often no obvious symptoms of this disease
– Importance of regular blood pressure check

69. Neuromuscular Disorders
• Electrolyte imbalances can alter nervous
system and muscle function
– Seizures: uncontrollable muscle spasms
– Muscle cramps: involuntary, spasmodic, and
painful muscle contractions

70. Obesity
• Popularity of sweetened beverages (U.S.)
– 21% of calories from beverages: sweetened soft
drinks, fruit juices, sweetened bottled waters,
bottled teas, specialty coffee
– Appetite not curbed: extra calories from drinks are
not compensated for by eating less
– Displace more nutritious beverages such as milk
(source of protein, calcium, vitamin D, and other
nutrients important for bone health)

72. Why Is Water So Important?
• Water is the most abundant substance in the
body
• Average healthy adult is 45–75% water
depending on
– Age
• Percent of water declines with age
– Composition of fat and muscle
• Muscle is ~65% water
• Fat is 10–40% water
– Gender

73. Figure 11.1
The Composition of the Body

74. Figure 11.2
Why Is Water So Important?
• Water is a
polar
molecule
– Excellent
solvent in
the body
– Neutral
charge
– Essential in
maintaining
acid-base
balance

75. Quick Review
• Body is more than 45% water
• Muscle tissue has more water than does fat
tissue
– Men have more body water than women
– Younger individuals have more body water than
older individuals
• Water is polar
• Water serves as an acid-base buffer

76. Functions of Water in the Body
You can survive for weeks without food,
but you can survive only a few days without water

77. Functions of Water in the Body
• Commonly known as a universal solvent
• Polarity allows it to attract charged particles into
solutions and dissolve a variety of other polar
substances
– Important to digestion
• Helps transport dissolved nutrients and other
substances throughout the body
• Blood is composed of water and red blood cells
– Water allows blood to transport oxygen, nutrients, and
hormones to cells
– Water helps transport waste products away from cells to
be excreted

78. Figure 11.3
Water Helps Regulate Body Temperature

79. Functions of Water in the Body
• Lubricates joints, sensitive eye tissues, mouth,
and intestinal tract
• Provides a protective cushion, bathing certain
organs with fluid
– During pregnancy the fetus is surrounded by
watery amniotic fluid
• Provides a structural component to cells

80. Functions of Water in the Body
• Water is essential for most chemical reactions
in the body
– During digestion water hydrolyzes the bonds
holding together
• Carbohydrate molecules
• Protein molecules
• Fat molecules
– When smaller molecules combine through
condensation water is formed

81. Quick Review
• Water
– Universal solvent
– Transports oxygen and nutrients throughout the body
– Absorbs and releases heat to regulate body
temperature
– Acts as a lubricant
– Provides a protective cushion for organs
– Adds structure to cells
– Participates in chemical reactions
• Hydrolysis
• Condensation

82. Amount consumed = Amount excreted
Figure 11.4
Maintaining Water Balance
• Fluid homeostatis
– Is necessary for
normal reactions
within the cells
– Is maintained by
adaptation to
changes in water
intake and water
loss
– Water balance

83. Sources of Body Water
• Largest source comes from beverages
• Food is an additional source
– Except for fats, all food contains some water
• Metabolic water – water generated during
metabolism
These sources contribute to an average daily intake
of 2,550 ml (about 2 quarts)

84. Water Excretion
• Majority of fluid is excreted through the kidneys
– More water that is ingested the more urine that is
produced
• Excreted through intestinal fluids in the stool
– Dependant on dietary intake of plant fibers and
presents of diarrhea
• Evaporated through exhalation and through the
skin
– Insensible water loss

85. Water Excretion
• Loss through sweat
– Varies based on
• Environmental factors
– Temperature
– Humidity
– Wind
– Sun’s intensity
– Clothing
• Amount of physical activity

86. Figure 11.5
Water Balance between Fluid Compartments
• Body fluid is
located
– Intracellular –
within the cells
– Extracellular –
outside the cells

87. Electrolytes Participate in Fluid
Balance
• Electrolytes
– Minerals with electrically charged ions
• Potassium
• Phosphate
• Magnesium
– Help maintain water balance between
compartments
• Sodium has greatest effect on fluid balance
- Calcium
- Chloride
- Sodium

88. Electrolytes Participate in Fluid
Balance
• Osmosis
– Strongest factor influencing water balance
between compartments
– Water moves from a diluted concentration to a
more concentrated area
– Osmolarity of a solution indicates total
concentration

89. Figure 11.6
Osmosis

90. Electrolytes Participate in Fluid
Balance
• Sodium-potassium pump
– Sodium and potassium play a key role in water
concentration inside and outside of the cells
– Healthy cells
• Low concentration of sodium ions
• High levels of potassium inside the cells
– Water is attracted to sodium and moves toward it
– Transports three Na+ ions out of the cell in
exchange for two K+ ions
• Keeps the cell from swelling and bursting

91. Quick Review
• Water balance
– Water is consumed and is produced by the body via
food, beverages, and metabolism
EQUALS
– Water excreted through the kidneys, skin, lungs, and
feces
• Body water is contained in either
– Intracellular fluid compartments – majority of body
water
– Extracellular fluid compartments
• Interstitial
• Intravascular

92. Quick Review
• Osmosis is the process of water moving from
an area of higher concentration to an area of
lower concentration across a cell membrane
• Sodium-potassium pump helps maintain
electrolyte and fluid balance inside and
outside of cells

93. How Do Water and Sodium Affect
Blood Pressure?
• If the body retains too much fluid, blood
volume increases and blood pressure will
likely rise
• Kidneys help regulate blood volume and
electrolyte balance through tightly
controlled hormone signals

94. How Do Water and Sodium Affect
Blood Pressure?
• Three hormones and one enzyme work together
to orchestrate the retention and excretion of
water and electrolytes base on blood volume
• Hormones
– Antidiuretic hormone (ADH), also called vasopressin
– Angiotensin
– Aldosterone
• Enzyme
– Renin

95. ADH
• Blood volume drops
– Hypothalamus detects decrease in blood pressure
and increase in concentration of salts
– Thirst mechanism and fluid intake are stimulated
– Hypothalamus stimulates pituitary glands to
release ADH
– ADH stimulates the kidneys to reabsorb water and
decrease urine output
– Blood volume increase and osmolality returns to
normal

96. Renin
• Blood pressure falls and sodium concentration
is reduced
– Renin is secreted by the kidneys
• Enzyme splits off a protein called angiotensin I from the
protein angiotensinogen found in the blood
• In the lungs angiotensin I is converted to angiotensin II
– Angiotensin II is a powerful vasoconstrictor

97. Aldosterone
• Renin-angiotensin system adapts to changes in
dietary sodium intake
– Consume too little sodium
– Osmolality drops in extracellular fluid (ECF)
– Fluid shifts from the blood to the interstitial fluid
– Blood volume and blood pressure decrease
– Angiotenson II triggers the adrenal glands to release
aldosterone
• Aldosterone
– Signals kidneys to retain more sodium
– Indirectly leads to water retention

98. Figure 11.8
Blood Volume Regulates Blood Pressure

99. Quick Review
• Changes in blood volume and osmolality
– Body takes actions to maintain homeostasis and
return blood pressure to normal
– Antidiuretic hormone (ADH) and aldosterone direct
the kidneys to reabsorb water and sodium
– Renin increases sodium retention
– Angiotensin II is a vasoconstrictor
• These control mechanisms adjust to the changes
in dietary sodium and fluid intake to prevent
hypertension

100. How Much Water? What Are the
Best Sources?
• Water needs depend on
– Physical activity
– Environmental factors
– Diet
• Recommendations
– 80% intake from beverages and 20% from food
– Adult women: approximately 9 cups of fluid per day
– Adult men: approximately 13 cups of fluid per day
– A well-balanced 2,200 kilocalorie diet that includes
beverages at all meals and snacks will provide about
12 cups of water

101. Figure 11.9
Daily Beverage Recommendations

102. How Much Water? What Are the
Best Sources?
• Drinking bottled or tap water, milk, and
juices throughout the day can help meet
the body’s needs
• Most foods can also contribute to daily
water need
– Fruits and vegetables can be 70% or more
water by weight
– Dry grain products provide some water

103. Quick Review
• Daily water needs vary according to
– Physical activity levels, environment, diet
• Adult women should consume about 12 cups per day
– 9 cups from beverages
– 3 cups from food
• Adult males should consume about 16 cups per day
– 13 cups from beverages
– 3 cups from foods
• Active individuals will need more water to avoid
dehydration

104. Do Diuretics Like Caffeine and
Alcohol Affect Water Balance?
• Alcoholic drinks, regular coffee, and tea
contribute to total water intake
• Alcohol and caffeine are considered diuretics
– Contribute to water loss
– Overconsumption can upset fluid balance

105. Caffeine
• Mild diuretic that blocks the action of ADH in
the kidneys
• Research unable to confirm that this mild
diuretic actually results in dehydration
• Caffeine doesn’t cause a significant loss of
body water over the course of the day
compared to noncaffeinated beverages
• Tolerance to diuretic effects develops over
time

106. Alcohol
• Inhibits ADH
• Can induce urination as quickly as 20 minutes
after consumption
• Can be dehydrating
• Effects electrolytes, especially potassium
• Older drinkers are less effected than younger
drinkers
• To prevent dehydration
– Reduce alcohol consumption
– Drink water after consuming alcohol

107. Diuretic Medications Can Help Treat
Hypertension
• First line of treatment for hypertension
– Often pharmaceutical diuretics
• Promote diuresis by inhibiting the reabsorption of
sodium
• Increased sodium excretion increases fluid excretion
• Reduces blood volume and lowers blood pressure
• Some diuretics increase potassium loss and
the risk of hypokalemia

108. Quick Review
• Moderate caffeine intake does not affect fluid
balance
• Alcohol reduces the effects of ADH and can
cause dehydration
• Pharmaceutical diuretics are prescribed to
reduce hypertension
• Pharmaceutical diuretics may cause
electrolyte imbalances

109. Effects of Too Much Water
• Water intoxication
– Rare in healthy individuals who consume a balanced
diet
– Drinking fluid too fast without adequate sodium
replacement depletes sodium and increases the rate
of urine production
• Results in hyponatremia
– Can cause swelling in the brain
• Fatique
• Confusion
• Disorientation

110. Effects of Too Little Water
• Dehydration can result from
– Not drinking enough water
– Losing excessive amounts of water due to diarrhea,
vomiting, high fever, or use of diuretics
– As little as a 2% loss of body water can trigger
• Loss of short-term and long-term memory
• Lower attention span and cognition
• Reduced ability to maintain core temperature
• Increase risk of urinary tract infections and fatigue
• Consequences of dehydration can be severe for
children, elderly, and athletes

112. Figure 11.11
Thirst Mechanism Signals Dehydration
• Thirst is often the first
sign of dehydration
• Urge to drink is
important in preventing
dehydration and
restoring water balance
• Less circulating blood
can lead to
Reduced blood pressure
Hypotension if severe
enough

113. Thirst Mechanism Signals
Dehydration
• Hypovolemia and hypotension can
– Reduce cardiac output
– Impair digestion
– May cause fainting and blacking out
• When dehydrated
– Water is depleted from extracellular fluid and
intracellular fluid

114. Monitor Water Intake to Avoid
Overhydration and Dehydration
• Measure body weight before and after long
bouts of vigorous physical activity or labor
and note changes
– If weighs less after an activity the change is due
to loss of body water
– If weight gain is noted overhydration is likely
• Consume less fluid before next activity

115. Monitor Water Intake to Avoid
Overhydration and Dehydration
• Urine color can be used to assess hydration
– Individuals who are dehydrated produce less
urine due to the release of ADH
– With dehydration urine is more concentrated and
darker in color
– Darker urine indicates possible need to increase
fluid intake

116. Putting It All Together
• Water is
– A universal solvent
– The main component of fluids in which all reactions
involving the energy-producing nutrients take place in
the body
• Vitamins and minerals aid in these chemical reactions
• Nutrients work in conjunction with water to
meet metabolic needs
• Consuming a wide variety of foods from all food
groups, with an emphasis on maintaining
sufficient fluid intakes, is the best diet
prescription to meet the body’s needs for
carbohydrate, proteins, fat, vitamins, minerals,
and water

117. Thank you!