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Chapter 12 – Water and the Major Minerals
Learning Objectives
After completing Chapter 12, the student will be able to:
1. List the uses of water in the body.
2. Describe water balance and the sources of water for the body.
3. Describe the effects of inadequate and excessive intakes of water.
9. Identify the role of sodium in the body and the effects of excessive or inadequate sodium.
10. Identify the food sources of sodium and the daily Tolerable Upper Intake Level.
11. Identify the role of chloride in the body.
12. Describe the role of potassium in the body and effects of excessive and inadequate intake.
13. Identify food sources of potassium.
14. Describe the role of calcium in the body and the factors that enhance or limit its absorption from the diet.
15. Identify food sources of calcium and the recommended dietary intake of calcium.
Assignments and Other Instructional Materials
The following ready-to-use assignments are available in this chapter of the instructor’s manual:
• New! Case study
• Worksheet 12-1: How to Interpret Calcium Serum Levels1
Other instructional materials in this chapter of the instructor’s manual include:
• Answer key for How To (pp. 396, 405) activities
• Classroom activities
• Worksheet answer keys (as appropriate)
• New! Handout 12-1: RDA/AI and UL for Major Minerals Compared
1 Worksheets 12-1, 12-2, and 12-5 contributed by Daryle Wane.
2 Worksheet 12-3 and Handout 12-1 contributed by Sharon Rady Rolfes
3 Contributed by Mary A. Wyandt, Ph.D., CHES
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Lecture Presentation Outline4
“Of special interest to...” symbol key: = Hot Topic = Personal Health
= Health Care Professionals = Science Majors
Key to instructor resource annotations (shown to the right of or below outline topics):
PL = Available on Power Lecture DVD-ROM (ISBN 0538797592)
TRA = Transparency acetates: 12e TRA = 12th edition, 11e TRA = 11th edition, 10e TRA = 10th edition
I. Water and the Body Fluids
The main role of water is to maintain an appropriate water balance to support vital functions. To maintain
water homeostasis, intake from liquids, foods, and metabolism must equal losses from the kidneys, skin, lungs,
and feces.
A. Water’s roles in the body
1. Carries nutrients and waste products.
2. Maintains the structure of large molecules.
B. Water Balance and Recommended Intakes
1. Intracellular fluid (inside the cells) makes up about two-thirds of the body’s water.
2. Extracellular fluid (outside the cells) has two components—the interstitial fluid and plasma.
3. Water Intake
a. Thirst is a conscious desire to drink and is regulated by the mouth, hypothalamus, and nerves.
b. Dehydration occurs when water output exceeds input due to an inadequate intake or excessive
losses.
1. Symptoms of a 1%-2% loss of body weight include thirst, fatigue, weakness, vague
discomfort, and loss of appetite.
4. Water sources include water, other beverages, fruit, vegetables, meat, cheese, and the byproduct of
metabolism. An intake of 1450 to 2800 milliliters of water is usually represented by:
a. Liquids – 550 to 1500 mL.
6. Water Recommendations IM WS 12-2, CI 12.1
a. 1.0 to 1.5 mL/kcal expended for adults (approximately 2-3 liters for a 2,000 kcalorie expenditure.
b. 1.5 mL/kcal expended for infants and athletes.
f. Both caffeine and alcohol can have a diuretic effect.
7. Health Effects of Water
a. Meeting fluid needs.
8. Kinds of water IM CI 12.2
a. Hard water
1. Water with high calcium and magnesium content.
b. Soft water
1. Water with high sodium and potassium content.
c. Other types of water:
1. Artesian water – water drawn from a well that taps a confined aquifer in which the water in
under pressure.
2. Bottled water – drinking water sold in bottles
3. Carbonated water – water that contains carbon dioxide gas, either natural or added.
C. Blood Volume and Blood Pressure – Fluids are essential to the regulation of blood volume and blood
pressure. 10e TRA 128; 12e TRA 18
1. ADH and water retention
a. Antidiuretic hormone (ADH) is released from the pituitary gland and causes kidneys to reabsorb
2. Renin
a. Kidneys release renin to reabsorb sodium.
b. Helps to restore blood pressure and blood volume.
3. Angiotensin
4. Aldosterone
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D. Fluid and Electrolyte Balance – Several minerals including sodium, chloride, potassium, calcium,
phosphorus, magnesium, and sulfur are involved in fluid balance.
1. Dissociation of Salt in Water 10e TRA 130
a. Dissociates into positive ions called cations and negative ions called anions.
2. Electrolytes Attract Water
3. Water Follows Electrolytes 11e TRA 25; 10e TRA 131
a. Sodium and chloride are primarily outside the cell.
4. Proteins Regulate Flow of Fluids and Ions
a. Proteins attract water and regulate fluid balance.
5. Regulation of Fluid and Electrolyte Balance
a. Digestive juices of GI tract contain minerals and these are reabsorbed as needed.
E. Fluid and Electrolyte Imbalance – Medications and medical conditions may interfere with the body’s
ability to regulate the fluid and electrolyte balance.
1. Different Solutes Lost by Different Routes
2. Replacing Lost Fluids and Electrolytes
F. Acid-Base Balance – The body must maintain an appropriate balance between acids and bases to sustain
life. Acidity in measured by the pH value, the concentration of hydrogen atoms. 10e TRA 132
1. Regulation by the Buffers
a. First line of defense.
2. Regulation in the Lungs
a. Respiration speeds up and slows down as needed to restore homeostasis.
3. Regulation in the Kidneys
a. Selects which ions to retain and which to excrete.
b. The urine’s acidity level fluctuates to keep the body’s total acid content balanced.
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II. The Minerals—An Overview IM CI 12.1, 12.3, HN 12-1
Major minerals are found in large quantities in the body, while trace minerals are found in small quantities.
Minerals receive special handling in the body. They may bind with other substances and interact with other
minerals, thus affecting absorption.
B. The Body’s Handling of Minerals
1. Some behave like water-soluble vitamins.
2. Some behave like fat-soluble vitamins.
3. Excessive intake of minerals can be toxic.
C. Variable Bioavailability
1. Binders in food can combine chemically with minerals and prevent their absorption.
III. Sodium
Sodium is one of the primary electrolytes in the body and is responsible for maintaining fluid balance. Dietary
recommendations include a moderate intake of salt and sodium. Excesses may aggravate hypertension. Most of
the sodium in the diet is found in table salt and processed foods.
A. Sodium Roles in the Body
1. Maintains normal fluid and electrolyte and acid-base balance.
B. Sodium Recommendations
1. Minimum adults: 500 mg/day
2. Adequate Intake
4. Maximum % Daily Value on food labels is set at 2400 mg/day.
C. Sodium and Hypertension
1. Salt has a great impact on high blood pressure. Salt restriction does help to lower blood pressure.
D. Sodium and Bone Loss (Osteoporosis)
1. High sodium intake is associated with calcium excretion.
E. Sodium in Foods IM CI 12.4; Website HN 12-2
1. Large amounts in processed foods (approximately 75% of sodium in the diet).
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4. Moderate amounts in meats, milks, breads, and vegetables (approximately 10% of sodium in the diet).
F. Sodium Deficiency
1. Sodium and water must be replaced after vomiting, diarrhea, or heavy sweating.
G. Sodium Toxicity and Excessive Intakes
1. Edema and acute hypertension.
IV. Chloride
Chloride in an essential nutrient that plays a role in fluid balance. It is associated with sodium and part of
hydrochloric acid in the stomach.
A. Chloride Roles in the Body
1. Maintains normal fluid and electrolyte balance.
2. Part of hydrochloric acid found in the stomach.
3. Necessary for proper digestion.
B. Chloride Recommendations and Intakes
1. Recommendations
a. Adequate Intake
1. For those 19-50 years of age, 2,300 mg/day.
2. Chloride intakes
a. Abundant in foods.
b. Abundant in processed foods.
C. Chloride Deficiency and Toxicity
1. Deficiency is rare.
V. Potassium
Potassium is another electrolyte associated with fluid balance. It is associated (inversely) with hypertension. It
is found in fresh foods—mostly fruits and vegetables.
A. Potassium Roles in the Body
1. Maintains normal fluid and electrolyte balance.
2. Facilitates many reactions.
B. Potassium Recommendations and Intakes 10e TRA 133; IM CI 12.4
1. Adequate Intake – For all adults, 4,700 mg/day.
C. Potassium and Hypertension
1. Low potassium intakes increase blood pressure.
2. High potassium intakes prevent and correct hypertension.
D. Potassium Deficiency
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1. Symptoms include muscular weakness, paralysis, confusion, increased blood pressure, salt sensitivity,
kidney stones, and bone turnover.
2. Later signs include irregular heartbeats, muscle weakness, and glucose intolerance.
E. Potassium Toxicity
1. Results from supplements or overconsumption of potassium salts.
VI. Calcium
Most of calcium (99%) is found in the bones. The remaining calcium (1%) is found in the blood and has many
A. Calcium Roles in the Body
1. Calcium in Bones
a. Hydroxyapatite are crystals of calcium and phosphorus.
2. Calcium in Body Fluids
3. Calcium and Disease Prevention
a. May protect against hypertension.
b. DASH diet that is rich in calcium, magnesium, and potassium.
c. May be protective relationship with blood cholesterol, diabetes, and colon cancer.
4. Calcium and Obesity
5. Calcium Balance 10e TRA 134, 135; IM WS 12-1
a. Works with vitamin D.
b. Works with parathyroid hormone and calcitonin.
6. Calcium Absorption
1. Stomach acid.
2. Vitamin D.
3. Lactose.
4. Growth hormones.
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B. Calcium Recommendations and Sources IM WS 12-3
1. Calcium Recommendations
a. AI adolescents: 1300 mg/day.
2. Calcium in Milk Products 10e TRA 136
3. Calcium in Other Foods IM CI 12.5
a. Tofu, corn tortillas, some nuts, and seeds.
b. Mustard and turnip greens, broccoli, bok choy, kale, parsley, watercress, and seaweed (nori).
D. Calcium Deficiency
1. Osteoporosis is the disease where the bones become porous and fragile due to mineral losses.
2. No obvious symptoms of mineral loss in bones appear. It is silent.
3. Deficiency in children can present as stunted growth.
4. Toxicity symptoms include constipation, increased risk of urinary stone formation, kidney dysfunction,
and interference with the absorption of other minerals.
VII. Phosphorus
Most of the phosphorus is found in the bones and teeth. It is also important in energy metabolism, as part of
phospholipids, and as part of genetic materials.
A. Phosphorus Roles in the Body
1. Mineralization of bones and teeth.
2. Part of every cell.
B. Phosphorus Recommendations and Intakes
1. RDA adults: 700 mg/day for ages 19-70 years.
C. Phosphorus toxicity symptoms include the calcification of nonskeletal tissues, especially the kidneys.
VIII. Magnesium
Magnesium supports bone mineralization, and is involved in energy systems and in heart functioning. It is
widespread in foods.
A. Magnesium Roles in the Body
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B. Magnesium Intakes
1. RDA adult men: 400 mg/day for 19-30 years of age.
2. RDA adult women: 310 mg/day for 19-30 years of age.
5. Hard water and some mineral waters.
C. Magnesium Deficiency
1. Deficiencies are rare.
2. Symptoms
a. Weakness and confusion.
3. Develops from alcohol abuse, protein malnutrition, kidney disorders, and prolonged vomiting and
diarrhea.
D. Magnesium and Hypertension
1. Protects against heart disease and hypertension.
2. Low magnesium restricts walls of arteries and capillaries.
E. Magnesium Toxicity
1. Symptoms from nonfood magnesium are diarrhea, alkalosis, and dehydration.
IX. Sulfate
Sulfate requirements are met by consuming a varied diet. It is found in essential nutrients including protein.
There is no recommended intake and there are no known deficiencies (apart from PEM).
X. Highlight: Osteoporosis and Calcium IM CI Highlight
Osteoporosis is one of the most prevalent diseases of aging. Strategies to reduce risks involve dietary calcium.
A. Bone Development and Disintegration
1. Cortical bone is the outer shell compartment of bone.
a. Creates the shell of long bones.
2. Trabecular bone is the inner lacy matrix compartment of bone. 10e TRA 137
a. Can be affected by hormones in the body signaling the release of calcium.
3. Women are affected 6 times as often as men.
3. Losses of both trabecular and cortical bone result in type II osteoporosis. 10e TRA 138; IM CA 12-2
a. Can result in compression fractures of the spine.
b. Hip fractures can develop.
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B. Age and Bone Calcium 10e TRA 139; IM CA 12-3
1. Maximizing Bone Mass
a. Children and adolescents need to consume enough calcium and vitamin D to create denser bones.
b. Hormonal changes can increase calcium losses.
C. Gender and Hormones
1. Men at lower risk than women.
2. Hormonal changes.
D. Genetics and Ethnicity
1. Genes may play a role: risk for African Americans < for Caucasians < Asians or Central/South
Americans.
E. Physical Activity and Body Weight
1. Muscle strength and bone strength go together.
2. Heavy body weights and weight gains place a stress on bones and promote bone density.
F. Smoking and Alcohol
1. Smokers
a. Less dense bones.
G. Dietary Calcium – the key to prevention
H. Other Nutrients
1. Adequate protein.
2. Adequate vitamin D.
3. Vitamin K protects against hip fractures.
I. A Perspective on Supplements
1. Calcium-rich foods are best.
2. Supplements may be needed when requirements are not met through foods.
3. Types of supplements
a. Antacids contain calcium carbonate.
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Case Study5
Michael is a 17-year-old high school football player who has recently been doing “two a day” practices in
preparation for the upcoming season. He is in good physical condition at 5 feet 10 inches and 165 pounds. He is
attempting to gain weight, so he has increased his intake of protein foods and estimates he eats approximately 3500
kcalories a day. One particularly hot afternoon, Michael is sweating profusely and begins to feel weak and has a
difficult time keeping up with his usual practice routines. Noticing that his face is visibly flushed, his coach has him
sit out of practice. Michael reports having eaten 2 peanut butter and jelly sandwiches, potato chips, and a can of soda
for lunch about 2 hours before practice. He had a breakfast burrito with eggs and cheese for breakfast with a 12-
ounce glass of orange juice.
1. What signs of dehydration does Michael exhibit?
2. Based on these signs of dehydration, what percentage of body fluid would you estimate Michael has lost?
3. Along with water, what essential nutrients has Michael’s body most likely lost as result of his heavy sweating?
4. Using his reported caloric intake, estimate Michael’s fluid needs.
5. Besides fruit juice and soda, what foods and beverages would you encourage to meet Michael’s fluid
requirements?
6. What food groups appear to be deficient in Michael’s usual diet? What essential nutrients are likely to be
lacking as a result of his limited diet?
7. Using information in this chapter and the simplified point system on page 405, estimate Michael’s calcium
intake. Is this adequate for his age? If not, what recommendations for increasing his calcium intake would you
offer?
Answer Key:
1. Flushed skin, impaired physical performance, weakness.
Suggested Classroom Activities
This chapter offers students the opportunity to learn many exciting things about the body fluids and major minerals.
The highlight that follows (Osteoporosis and Calcium) is a subject of great interest and controversy and usually
leads to lively class discussion. Several vitamin activities have been presented in Chapter 10 of this manual that can
also be used in the study of this Chapter. Please see Classroom Activities 10-3, 10-4, 10-5, 10-6, 10-7, 10-8, and 10-
9.
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Classroom Activity 12-1: Chapter Opening Quiz
Objective: Introduction to chapter Class size: Any
Instructions: As a way of introducing any new chapter, give a quiz to the class. This is a quiz designed to be
projected overhead. For details, please see Chapter 1, Classroom Activity 1-7.
Classroom Activity 12-3: Using Bags of Flour to Display Bone Losses During Osteoporosis
Key concept: Bone density Class size: Any
Materials needed: 6 zip-lock plastic bags, 6 labels, 1 bag of all-purpose flour (29 cups)
Instructions: Before class, obtain 6 clear zip-lock plastic bags, labels, and a bag of flour. Add flour to each bag in the
following amounts:
Classroom Activity 12-4: Consumer Brochures on Major Minerals6
Key concept: Nutrition messages on minerals Class size: Small to medium
Instructions: Ask students to select one of the minerals outlined in this chapter and write a three-fold flyer on it that
could be used for patient education.
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How To “Try It” Activities Answer Key
How to Cut Salt (and Sodium) Intake
How to Estimate Your Calcium Intake
189 mg Ca per ½ cup almonds, 21 mg Ca per ½ cup broccoli, and 148 mg Ca per ½ cup yogurt (per USDA Nutrient
Data Laboratory)
Critical Thinking Questions7
These questions will also be posted to the book’s website so that students can complete them online and e-mail their
answers to you.
1. Explain how homeostatic controls within the body are involved in regulating intracellular, intravascular, and
other extracellular fluids and the compounds dissolved in them.
Answer: Maintenance of Blood Volume and Blood Pressure: While this is not an activity that is performed by
water or fluids by themselves, the importance of fluids for blood volume and blood pressure should be obvious.
Acid-Base Balance: Maintaining the pH within a very narrow range in the body is a delicate balancing act
among the lungs, the kidneys, and the blood. Metabolic and respiratory problems can result in acidosis or
alkalosis and with the help of the kidneys via the blood, pH can be restored.
Bicarbonate is an alkaline compound produced in the body. Its level is controlled by the kidneys in times of
acidosis or alkalosis in that the kidneys will either reabsorb more of the bicarbonate in the former situation or
excrete more of the bicarb in the latter situation.
2. Discuss the multiple roles of water in body fluids. Provide an example of what might happen if enough water is
not available to the body for each particular function, or give a clinical example of the particular function.
