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Lecture
Outline
Chapter 9
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Water and Minerals
Chapter 9
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chapter
Chapter Learning Outcomes
1. Discuss the functions of water in the body as
well as typical sources of intakes and losses.
2. Discuss how the body maintains its water
balance.
3. List major signs and symptoms of heat-related
illnesses.
4. Classify mineral nutrients as major, trace, or
ultratrace minerals.
5. Describe factors that can affect the absorption,
retention, and availability of mineral nutrients.
Chapter Learning Outcomes
(continued)
6. List key functions and major food sources of
mineral nutrients.
7. Identify signs and symptoms associated with
deficiencies as well as excesses of mineral
nutrients.
8. Describe roles of minerals in achieving and
maintaining good health.
9. Identify major risk factors for hypertension and
osteoporosis.
Quiz Yourself
True or False

1. Your body constantly loses water through
insensible perspiration, a form of water loss that
is not the same as sweat. T F
2. Ounce per ounce, cottage cheese contains
more calcium than plain yogurt. T F
3. Potassium, sodium, and chloride ions are
involved in fluid balance. T F
4. Arsenic is an ultratrace mineral. T F
5. In general, plants are good dietary sources of
iron because the plant pigment chlorophyll
contains iron. T F
Quiz Yourself
True or False

1. True Your body constantly loses water through
insensible perspiration, a form of water loss that
is not the same as sweat.
2. False Ounce per ounce, cottage cheese
contains less calcium than plain yogurt.
3. True Potassium, sodium, and chloride ions are
among the ions involved in fluid balance.
4. True Arsenic is an ultratrace mineral.
5. False In general, plants are not good dietary
sources of iron. The plant pigment chlorophyll
contains magnesium not iron.
Water
Water (H2O)
– Comprised of 2 hydrogen atoms and 1 oxygen
atom
– Needs no digestion and is easily absorbed
– Makes up 45 to 75% of body weight
Elderly ~45% Infants ~75%
– Major solvent
– Very essential—without water, death occurs
within 1 to 2 weeks.
Body Temperature Regulation
Metabolism generates body heat
– If body temperature reaches 1060 F, excess
heat denatures enzymes and damages body
tissues which may result in death.
– Evaporation of water in perspiration releases
heat to maintain normal body temperature.
Each liter of perspiration that evaporates
represents loss of ~500 kcal of energy.
Body Water Compartments
Intracellular water (fluid): water inside cells
Extracellular water (fluid): water surrounding cells
or in blood vessels (plasma)
Plasma membrane of human cell is selectively
permeable
Osmosis — the diffusion (movement) of water
through a selectively permeable membrane
Concentration of substances dissolved in water
influences osmosis
Body Water Distribution
Simple diffusion – molecular movement
from a region of higher to lower concentration
Insert figure 9.1
Body Water Distribution
Osmosis – movement of water through a
selectively permeable membrane
Insert Figure 9.2
Two Major Water Compartments
Intracellular Water
Water inside the cells
~ 2/3 of body water is intracellular
Extracellular Water
Water surrounding the cells or in the fluid portion of
blood (plasma)
Balance between intra- and extracellular fluid is
maintained by concentration of ions.
Main ions = sodium, potassium, chloride, and
phosphate
Fluid Compartments in the Body
•
Insert Figure 9.3
Maintaining Proper Hydration
Hydration refers to adequate water status
shifts in ion concentration can affect hydration.
Insert figure 9.1
Sources of Water
Total Water Intake
– Includes water in beverages and foods
•
Water weight of fruits and vegetables typically
ranges from 60 to 95%.
Metabolic Water
– Water formed by cells as a metabolic byproduct
How Much Water is in That
Food or Beverage?
•
Insert Table 9.1
The Essential Balancing Act
Body water is lost through:
– urine, perspiration, exhaled air, feces, and
insensible perspiration.
Insensible perspiration: body water that passes
through the skin and is not from sweat glands.
Typical fluid intake = fluid lost
Average is ~2.5 qt/d
Daily Water Balance
• Insert figure 9.5
Kidneys and Hydration
Kidneys:
– Are the major regulator of body’s water
content and ion concentration.
– Maintain proper hydration by filtering excess
ions from the blood.
• Remove excess sodium ions; water
follows sodium.
– Remove drugs and metabolic wastes.
• Urea and uric acid — waste products of
protein metabolism.
Water Conservation
•
•
Water conservation occurs when a person is
hot and perspires heavily.
Hormones that participate in sodium and water
conservation include:
-Antidiuretic hormone (ADH)
-Aldosterone
Effects of Antidiuretic Hormone and
Aldosterone on Kidneys
•
Insert Table 9.7
How Much Water Is Needed?
Adequate Intake (AI) for total water
(including water in foods) is:
Young Women = 11 cups (2.7 L)/day
Young Men = 15.5 cups (3.7 L)/day
Urine output is best indicator of adequate water
intake.
What Is a Diuretic?
Diuretics — substances that increase urine
output.
Two common diuretics:
Caffeine – In coffee, tea, “energy” drinks, and
soft drinks
Alcohol – In beer, wine, and spiritis
Inhibits ADH resulting in urinary water losses > amount of fluid
consumed
“Hangovers” may be an effect of
dehydration on the brain.
Dehydration
When the body’s fluid loses are greater
than its input, dehydration occurs.
• Weight loss is a sign of dehydration.
Every 16 oz of water lost by
the body represents 1 lb of
body weight.
Dehydration
Body fluid loss
Symptom/condition
1 to 2%
Fatigue and thirst
4%
7 to10%
Loss of muscular strength
and endurance
Severe weakness
20%
Death
People at Risk for Dehydration
•
Older adults – do not sense thirst as
quickly as younger people.
•
Sick people – especially sick children
with fever, vomiting, and diarrhea.
•
Athletes and people who work or
exercise outdoors in hot weather.
Can Too Much Water Be
Toxic?
Water intoxication – too much water
consumed at a time or conditions in which
kidneys have difficulty filtering water from
blood
•
Excess water dilutes sodium concentration of
blood, disrupting water balance
– Signs and symptoms:
•
Dizziness, headache, confusion, poor coordination,
bizarre behavior, and seizures
Minerals: Basic Concepts
What are minerals?
• Elements in Earth’s rocks, soil, and
natural water sources.
• About 15 mineral elements are
essential nutrients.
• Classified as micronutrients because
they are required in mg or mcg amounts.
Classifying Mineral Nutrients
•
Main categories of minerals
– Major
• Required in amounts >100 mg/d
– Trace
• Required in amounts <100 mg/d
– Ultratrace
• Body contains very small amounts
Minerals with Known or
Possible Roles in the Body
• Insert Table 9.2
Summary of Major Minerals
• Insert Table 9.3
Why Are Minerals Necessary?
Diverse roles, including:
–
–
–
–
–
–
–
–
Structural components of tissues
Ions
Blood clotting
Fluid balance
Acid-base balance
Cofactors in chemical reactions
Part of certain enzymes and hormones
Aid in energy release from macronutrients
Minerals and Their Functions
• Insert Table 9.8
Sources of Minerals
Most foods contain minerals
– Animal foods generally contain higher
amounts of minerals than plant foods.
– Processing often reduces mineral contents of
foods.
Bioavailability of minerals varies
– In general, minerals in animal foods are more
easily absorbed than minerals in plant foods.
Other Sources of Minerals
Tap water
• “Hard” water contains a variety of minerals,
including calcium, sulfur, copper, iron, and zinc.
• Most public water supplies provide optimal
fluoride levels, because the mineral has been
added to the water.
Dietary supplements
–
–
A daily multiple vitamin and mineral supplement is
generally safe for healthy people.
Supplements of single minerals may be toxic, if taken
in excess.
Mineral Intakes
Many minerals have
a narrow range of safe
intake. As a result, it is
relatively easy to
consume a toxic
amount, especially by
taking supplements
that only contain a
particular mineral.
• Inser
t
Figur
e 9.9
Major Minerals: Calcium
• The most plentiful mineral in human body
– > 99% is in bones and teeth
– ~ 1% is in extracellular fluid
• Healthy adults absorb ~25% of calcium.
– Absorption increases during growth.
– Absorption decreases with advanced age,
vitamin D deficiency, diarrhea, and high
intakes of phosphorus, oxalic acid, and
phytic acid.
Why Is Calcium Necessary?
Functions of calcium include:
•
•
•
•
•
•
Bone formation and maintenance
Structural component of teeth
Muscle contraction
Blood clot formation
Nerve impulse transmission
Cell metabolism
May help control blood pressure and immune
functioning
Bone Development and Maintenance
Bones are constantly remodeled in
response to physical stress.
• Remodeling involves two types of cells:
Osteoclasts — tear down bone tissue where
it is not needed
Osteoblasts — add bone to where it is
needed
Thyroid and Parathyroid Glands
• Insert
Figure
9.11
Role of Thyroid and Parathyroid
Glands
Thyroid gland:
Secretes calcitonin when blood calcium is too high
• Stimulates osteoblasts
Parathyroid glands:
Secrete parathyroid hormone (PTH) when blood
calcium is too low
• Stimulates osteoclasts
Calcium Content of Selected Foods
• Insert Table
9.4
Good Food Sources of Calcium
• Insert figure
9.13
What is Osteoporosis?
Insert figure
9.14
• A chronic disease characterized
by low bone mass and reduced
bone structure leading to
increased risk of bone fractures
– Among people over age 50,
~10 million have osteoporosis and
34 million are at risk.
– An estimated 1.5 million Americans
have an osteoporosis-related
fracture each year.
Risk Factors for Osteoporosis
Insert Table 9.5
Calcium Toxicity
Upper Level (UL) is 2500 mg/d
– Excess calcium can result in
hypercalcemia
– Signs/symptoms:
» Kidney stones, bone pain, muscle
weakness, fatigue, and
hypertension
Sodium (Na)
• Table salt = sodium + chloride
– 1 tsp salt supplies 2325 mg sodium
• Why is Sodium Necessary?
– Major positively charged ion in
extracellular fluid
– Conducts nerve impulses
– Involved in transporting glucose and
amino acids into cells
Sodium Content of Selected
Foods/Food Additive
Insert Table 9.7
Dietary Adequacy for Sodium
• Only ~ 180 mg sodium required
per day
– AI = 1500 mg/d
• Those who perspire heavily lose
sodium in sweat and need more
Sodium Deficiency and Toxicity
• Deficiency
– May occur when > 2 to 3% of body weight
is lost through sweating
• Toxicity
– UL = 2300 mg/d
• Average American consumes >2500
mg/d
– High sodium intakes associated with
increased risk of hypertension
Sodium and Hypertension
• Hypertension — condition
characterized by persistently elevated
blood pressure
– Estimated 27% of American adults have
the condition
– Hypertension increases risk of:
• Heart disease
• Stroke
• Kidney failure
Blood Pressure
• Systolic pressure — maximum blood
pressure within arteries when ventricles
of the heart contract
• Diastolic pressure — pressure when
ventricles relax between contractions
Systolic value is always higher than
diastolic value
Categories of Blood Pressure
Levels in Adults
• Insert table
9.18
Many risk factors
for hypertension
can be controlled
by following a
healthy lifestyle.
Insert Table 9.9
Practical Steps to
Reduce Risk of
Hypertension
• Insert Table 9.10
Potassium (K)
Why is Potassium Necessary?
• Major positively charged ion in intracellular
fluid
– Needed for nerve impulses, contracting muscles,
and kidney function
– Potassium-rich diets may reduce blood pressure
Dietary Adequacy
– AI = 4700 mg/d
• Most Americans consume ~2700 mg/d
Good Food Sources of Potassium
Insert Figure 9.15
Potassium Content of Selected Foods
Insert Table 9.11
Magnesium (Mg)
• Participates in >300 chemical reactions
• Roles the body include:
– Regulation of muscle and nerve function
– Maintenance of strong bones
– Strengthening the immune system
• Dietary Adequacy
– Adult RDA = 310 to 420 mg/d
Magnesium Content of Selected Foods
Insert Table
9.12
Good Food Sources of Magnesium
Insert Figure
9.16
Magnesium Deficiency and
Toxicity
• Deficiency
• Rare among healthy Americans
• Most likely in girls between 14-18 yrs of
age
• Toxicity
• Results from ingesting excessive
laxatives, antacids, or dietary
supplements
Summary of Trace Minerals
• Insert Table
9.13
Iron (Fe)
Why is Iron Necessary?
• Iron is a component of hemoglobin and
myoglobin.
• Hemoglobin — iron containing protein in RBC
that transports oxygen to tissues and some
CO2 away from tissues
• Myoglobin — iron-containing protein in
muscle cells that controls oxygen uptake from
RBC
• Iron is involved in energy generation and
immune function.
Iron Content of Selected Foods
Insert Table 9.14
Good Food Sources of Iron
Insert Figure 9.17
Iron: Dietary Adequacy
• RDA
• Women = 18 mg/d
• Most females from ages 14 to 50
yrs have low intakes.
• Men = 8 mg/d
• Most males >age 9 yrs have
adequate intakes.
Iron Deficiency-Related Disorders
Anemia impairs oxygen transport in blood.
Normal RBC
Insert figure 9.18
Hypochromic,
microcytic RBC
Signs and Symptoms of Iron
Deficiency Anemia
Insert Table 9.15
Iron Toxicity
• Upper Limit (UL) = 45 mg/d
• May occur in children <6 yrs due to
supplement overdose
• Signs include vomiting and diarrhea,
progressing to coma and death
• Hereditary Hemochromatosis
• Common hereditary disorder resulting in
excess iron absorption
Zinc (Zn)
Why is Zinc Necessary?
• It’s a component of hundreds of
enzymes and other proteins.
• It is needed for:
• Wound healing
• Normal of taste and smell
• DNA synthesis
• Immune function
Zinc Deficiency
– Zinc deficiency often occurs in people
with chronic digestive tract problems
and exclusively breastfed infants.
– Associated with delayed sexual
maturation and growth retardation
Zinc Content of Selected Foods
Insert Table 9.16
Good Food Sources of Zinc
Insert Figure 9.20
Zinc: Dietary Adequacy and
Toxicity
• Adequacy
• Adult RDA ranges from 8 to 13 mg/d
• Children between 6 to 11 yrs at risk of
deficiency
• Toxicity
• Upper Limit (UL) = 40 mg/d
• May reduce HDL cholesterol level
• >100 mg/d results in diarrhea, cramps,
vomiting, and depressed immune system
Iodide (I)
Why is Iodide Necessary?
• Required for normal thyroid
function and production of the
thyroid hormone.
• The hormone controls the rate
of metabolism.
• Iodide is added to regular table
salt to prevent deficiency.
Iodide Content of Selected Foods
Insert Table 9.17
Iodide: Dietary Adequacy and
Toxicity
• Adequacy
• Adult RDA = 150 mcg/d
• Toxicity
• UL = 1.1 mg/d
• May result in enlargement of
thyroid gland
Dietary Deficiency of Iodide
Goiter
• Characterized by enlarged
thyroid gland
• Common before advent of
iodized salt in areas where iodine
content of soil was poor
Cretinism
• Condition affecting infants born to
women who were iodide deficient
during pregnancy
Selenium (Se)
Why is Selenium Necessary?
• Part of a group of proteins called
selenoproteins
• Many selenoproteins are antioxidants.
• May reduce risk of certain cancers
Selenium Content of Selected Foods
Insert Table 9.18
Dietary Adequacy, Deficiency,
and Toxicity of Selenium
• Adequacy
• Adult RDA = 200 mcg/d
• Most Americans meet the RDA
• Deficiency
• May occur with severe digestive tract
conditions
• Toxicity
• Upper Limit (UL) = 400 mcg/d
• Known as selenosis
Chromium (Cr)
Why is Chromium Necessary?
• May enhance insulin’s action on cell
membranes
• “Holds the door open” for glucose entry into
cells
Sources of Chromium
• Widely distributed in foods
Dietary Adequacy — most diets are adequate
Deficiency — causes impaired glucose tolerance
Toxicity — not known
Chromium Content of Selected Foods
Insert Table 9.16
Summary of Ultratrace Minerals
Insert Table 9.19
Chapter 9 Highlight
Bottled Water versus Tap Water
According to results of surveys, Americans drink bottled
water:
Taste preferences
Convenience
Drinking bottled water is expensive and
unnecessary, unless public water supply
is disrupted.
What is Bottled Water?
FDA Definition:
Water intended for human consumption
that is sealed in containers and has no
added ingredients other than a
substance that prevents growth of
microbes, such as bacteria.
Is Bottled Water Safe to Drink?
FDA regulates:
– Levels of contaminants in water such as
microbes, chemicals, and minerals
– Requires water be sampled, analyzed, and
found to be safe and clean before bottling
Is Tap Water Safe to Drink?
• The Safe Drinking Water Act requires water to
undergo a thorough purification process and
be tested for safety constantly.
• If testing indicates water may pose a threat to
public health, consumers are warned through
media, and a “boil order” may be issued.
• “Boil order” = boiling water for 10 minutes to kill
harmful microorganisms
FDA Definitions for Classifying
Some Types of Water
Insert Table
9.A