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229
Chapter 13 – The Trace Minerals
Learning Objectives
After completing Chapter 13, the student will be able to:
13.2 Identify the main roles, deficiency symptoms, and food sources for each of the trace minerals (iron, zinc,
iodine, selenium, copper, manganese, fluoride, chromium, and molybdenum).
13.3 Describe how contaminant minerals disrupt body processes and impair nutrition status.
13.4 Define phytochemicals and explain how they might defend against chronic diseases.
a. Describe the roles of phytochemicals in food and the physiological effects of phytochemicals in the
body.
b. List major phytochemicals that might protect the body from cancer and heart disease.
c. Describe functional foods and their role in disease prevention.
d. Identify methods to help the consumer evaluate the safety and effectiveness of functional foods.
Assignments and Other Instructional Materials
The following ready-to-use assignments are available in this chapter of the instructor’s manual:
• Case Study 13-1: Trace Mineral Deficiencies
• New! Case Study 13-2: Iodine and Hypothyroidism
Other instructional materials in this chapter of the instructor’s manual include:
• Answer keys for How To (p. 412) activity and study card questions
• Classroom activities, featuring New! meal comparison activity (13-1)
• Worksheet answer keys (as appropriate)
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I. The Trace Minerals—An Overview
A. Food Sources
1. Depends on soil and water composition
B. Deficiencies
1. Some are easy to recognize, while others can be difficult to diagnose
2. Mild deficiencies are easily overlooked
3. Do not exceed 100% Daily Values
D. Interactions
1. Common and coordinated to meet body needs
2. Can lead to nutrient imbalances
E. Nonessential Trace Minerals
1. Nickel
II. The Trace Minerals
A. Iron – Discuss the following:
1. Iron Roles in the Body
a. Ferrous iron is reduced and has a net positive charge of two
2. Iron Absorption (Figure 13-3) 10e TRA 140, 141
1. Ferritin
2. Transferrin
3. Iron Transport and Storage 10e TRA 142
a. Surplus is stored in bone marrow, spleen, and liver
b. Hemosiderin
c. Iron recycling (Figure 13-5)
d. Hepcidin
4. Iron Deficiency 10e TRA 143
a. Iron-deficiency anemia
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5. Assessment of Iron Deficiency IM CS 13-1
6. Iron Deficiency and Anemia – Discuss the difference between iron deficiency and iron-deficiency
anemia (Figure 13-6) 13e TRA 13
7. Iron Deficiency and Behavior
a. Energy metabolism is impaired
8. Iron Deficiency and Pica
9. Iron Overload IM WS 13-1
a. Hemochromatosis
b. Iron overload can also be caused by:
1. Repeated blood transfusions
2. Massive doses of supplemental iron
3. Rare metabolic disorders
c. Symptoms of iron overload
10. Iron and Chronic Diseases
a. Heart disease
b. Cancer
11. Iron Poisoning
12. Iron Recommendations
a. RDA for men: 8 mg/day for adults 19-50 years of age
13. Iron Food Sources (Figure 13-7) 10e TRA 144; IM CA 13-1
a. Red meats, fish, poultry, and shellfish
14. Iron Contamination
a. Food prepared in iron cookware takes up iron salts
b. Acidic foods and long cooking times increase uptake of iron salts
15. Iron Supplementation
a. Best absorbable form is ferrous sulfate or an iron chelate
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B. Zinc – Discuss the following:
1. Zinc Roles in the Body
a. Supports the work of metalloenzymes.
b. Stabilizes cell membranes and DNA
c. Involved in growth, development, and immune function
2. Zinc Absorption
a. Rate of absorption depends on zinc status
b. Phytates bind zinc
c. Metallothionein
3. Zinc Transport 10e TRA 145
4. Zinc Deficiency
5. Zinc Toxicity
6. Zinc Recommendations and Sources
a. Recommended intakes
1. RDA for men: 11 mg/day
2. RDA for women: 8 mg/day
b. Food Sources (Figure 13-10) 10e TRA 146
7. Zinc Supplementation IM CA 13-2
1. Iodide Roles in the Body
2. Iodine Deficiency IM WS 13-2
a. Goiter
b. Goitrogen (antithyroid) overconsumption
c. Cretinism
3. Iodine Toxicity
4. Iodine Recommendations and Sources
1. Selenium Roles in the Body
a. Defends against oxidation
b. Regulates thyroid hormone
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2. Selenium Deficiency
a. Predisposes the person to Keshan disease
b. Prevalent in regions of China
3. Selenium and Cancer – May protect against certain forms of cancer
4. Selenium Recommendations and Sources
5. Selenium Toxicity
1. Copper Roles in the Body
a. Absorption and use of iron in the formation of hemoglobin
2. Copper Deficiency and Toxicity
a. Deficiency is rare
3. Copper Recommendations and Sources
a. Recommendations – Adult RDA: 900 g/day
b. Sources
1. Seafood, nuts, seeds, and legumes
2. Whole grains
3. In houses with copper plumbing, water can be a source
F. Manganese – Discuss the following:
1. Manganese Roles in the Body
2. Manganese Deficiency and Toxicity
a. Deficiency symptoms are rare
1. AI for men: 2.3 mg/day
2. AI for women: 1.8 mg/day
b. Sources include nuts, whole grains, leafy vegetables, and tea
G. Fluoride – Discuss the following:
1. Fluoride Roles in the Body
a. Formation of teeth and bones
2. Fluoride Toxicity
3. Fluoride Recommendations and Sources
a. Recommendations
1. AI for men: 4 mg/day
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2. AI for women: 3 mg/day
1. Chromium Roles in the Body
a. Enhances insulin action and may improve glucose tolerance
b. Low chromium levels can result in elevated blood sugar levels
1. AI for men: 35 g/day
3. Chromium Supplements – Claims about reducing body fat and improving muscle strength remain
controversial IM CA 13-3
I. Molybdenum – Discuss the following:
1. Molybdenum functions as a cofactor for several enzymes
III. Contaminant Minerals – Discuss the following:
A. Lead Website HN 13-1, 13-2
IV. Highlight: Phytochemicals and Functional Foods IM WS 13-4
A. The Phytochemicals – give foods taste, aroma, color, and other characteristics IM CA 13-4
1. Defending against Cancer
a. Phytoestrogens mimic estrogen
1. Found in soybeans, legumes, flaxseeds, whole grains, fruits, and vegetables
4. Supplements may stimulate the growth of cancers that depend upon estrogen
b. Lycopene
1. Powerful antioxidant
2. Defending against Heart Disease
a. Flavonoids in foods
1. Powerful antioxidants
2. Protect against LDL cholesterol oxidation and reduce blood platelet stickiness
3. Lower risk of chronic diseases
4. Found in whole grains, legumes, soy, vegetables, fruits, herbs, spices, teas, chocolate, nuts,
olive oil, and red wines
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4. Reduce inflammation
5. Lignans, found in flax seed and whole grains
B. Functional Foods
1. Foods as Pharmacy
a. Margarine enhanced with a plant sterol may lower cholesterol
b. May be more useful in prevention and mild cases of disease
c. Drugs are used for severe cases of disease
C. Future Foods
1. Use of gene research
2. Can we design foods to meet exact health needs of each individual?
3. Can farmers grow the “perfect” foods?
Case Studies
5
Case Study 13-1: Trace Mineral Deficiencies
Belinda is a 10-year-old elementary school student who has come in for a physical examination. She is 4 feet 7
inches tall and weighs 120 pounds. Her doctor calculates her BMI at 27.9 (98th% for her age). Concerned about her
obesity, Belinda’s doctor asks about her diet and her physical activity. Her mother reports that Belinda has become
“lazy” and does not like to play outside with her friends after school. She says she is more irritable than usual and
complains about helping with household chores. Her mother worries that she may be depressed, although she can
think of no family issues that may be responsible for this behavior. Belinda sometimes skips breakfast or has cereal
and toast in the morning; she takes chips, a juice drink, and a cheese sandwich made with white bread for lunch; and
has a toaster pastry or cookies with milk for a snack after school. She doesn’t particularly like meat and frequently
asks for buttered pasta with cheese for dinner. Belinda says she eats vegetables “when my mom buys them.” A
blood test reveals a normal hemoglobin level, low serum iron, moderately elevated transferrin,, and low transferrin
saturation.
1. Based on her history, what nutrient deficiencies would you suspect may contribute to Belinda’s symptoms?
Explain your answer.
2. Based on the information in this chapter, what stage of iron deficiency do the results of her laboratory tests
indicate? How would you classify Belinda’s condition? Explain.
3. What are some meal planning strategies that Belinda’s mother could follow to improve her intake of iron and
zinc?
4. What are some meal and snack ideas that could improve Belinda’s intake of essential elements mentioned in
this chapter?
5. If her doctor prescribes an iron supplement, what practical advice would you give Belinda about when and how
to take it?
6. What cautions would you give Belinda’s mother regarding excessive supplementation of iron?
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Answer Key
1. Iron: deficiency is common in growing children and adolescents; symptoms of iron deficiency include fatigue,
apathy, and irritability, and can appear as behavior problems; relatively common in overweight children;
Case Study 13-2: Iodine and Hypothyroidism
Michelle F. is a 47-year-old woman who lives on the California coast. Her husband is a commercial fisherman.
Michelle eats a varied diet including fresh fish at least 3 times a week. She takes a daily multivitamin. Michelle has
recently been diagnosed with hypothyroidism. Her doctor has prescribed thyroid hormone therapy, to which she is
responding well. While driving home one day, she hears on a radio program that the best way to treat low thyroid
conditions is with a particular iodine supplement. She is considering whether to order this supplement.
1. What is the most common visible sign that could indicate that Michelle has an iodine deficiency?
2. What might be another cause of this visible sign besides an iodine deficiency?
3. Considering where she lives and what she eats, how likely is it that Michelle’s diet would be deficient in iodine?
Explain.
4. Based on the information in this chapter about the availability of iodine in foods in the United States, what other
factors make it unlikely that Michelle would have a deficiency of this nutrient?
5. What information from this chapter should make Michelle cautious about ingesting excessive amounts of
iodine?
6. Michelle notes that her daily multivitamin contains 225 micrograms of iodine. She also uses small amounts of
iodized salt in her cooking. Based on these facts, what decision should Michelle make regarding taking
additional iodine to treat her hypothyroidism? Explain your answer.
Answer Key
1. Goiter.
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Suggested Classroom Activities
This chapter offers students the opportunity to learn many exciting things about the trace minerals. There is far too
much material for instructors to expect students to grasp in-depth information on all of them. Some instructors prefer
to encourage students to learn a great deal about iron. Because we do know so much about iron, it can be used to
illustrate many nutrition principles that may be more valuable than memorized details about individual nutrients.
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 10-2 through 10-6.
Classroom Activity 13-1: Preventing Iron-Deficiency Anemia in Children (Meal Comparison)
6
Key concept: Applying iron intake recommendations Class size: Any
Instructions: Present the two children’s lunch meal plans below to students and use the discussion questions to
prompt them to evaluate the plans.
Lunch #1
Macaroni and cheese, 1 cup
Carrots, steamed, ½ cup
Pineapple, fresh, ½ cup
1% milk, ½ cup
Lunch #2
Turkey breast, diced, 2 ounces
Spinach, steamed, ½ cup
Tator tots, 1 ounce
Applesauce, ½ cup
1% milk, ½ cup
Discussion questions:
1. What is the EAR for iron for 4- to 8-year-old children?
2. Which foods provide the most iron in these meals? Why?
3. How could the iron content of either of the meals be improved?
4. Why is it potentially a problem for children (4-8 years old) to drink more than 2-3 cups of milk a day?
Answer key:
1. 4.1 milligrams/day
Nutrient composition of meals for instructor reference:
Lunch #1 Item
Cal
Fe
Vit C
Lunch #2 Item
Cal
Fe
Vit C
Macaroni and cheese, 1 cup
183
1.2
0
Turkey breast, diced, 2 oz
114
0.92
0
Classroom Activity 13-2: Research on Zinc Supplements
7
Key concept: Zinc supplementation Class size: Small to medium
Instructions: Zinc has several important functions in the body and is the subject of new drug discoveries that focus
on minimizing the effects of the common cold, flu, etc. Ask students to take a trip to a local pharmacy or drug store
and study the many supplements and cold and flu formulas and then write a report on the products that listed zinc on
the product label and the claims made by the product manufacturers. This report should also discuss current
238
evidence for the efficacy of these claims for the product, based on the roles and functions of zinc in the body.
Students should share their findings with classmates.
This is a great activity for the students, as zinc use to support immune function has increased. It is a good
opportunity for the students to see what is new on the market and learn what their potential clients may be taking in
addition to their dietary intake.
With this exercise, if students want to go in groups, they might want to quiz the pharmacist about zinc products and
supplements to learn what the pharmacist knows and what types of information the pharmacist shares with
customers and clients. Many customers turn to the pharmacist and now the nurse practitioners that work in the local
retail pharmacies. Future dietitians are wise to understand what their colleagues are discussing with customers and
forge networks so that these colleagues know where to refer when they need a nutrition professional!
Classroom Activity 13-3: Research on Chromium Supplements
Key concept: Chromium supplementation Class size: Small to medium
The students should study the articles to determine whether the research was well planned and the conclusions
reached were appropriate for the methodology of the study (in their opinion and based on where they are in their
curriculum with regard to nutrition research). Then have each student summarize the overall theme of the findings
on the efficacy for the mineral and state whether they believed the research authors drew solid conclusions that the
American consumer could and should believe.
Classroom Activity 13-2=4: Foods Containing Phytochemicals
How To “Try It” Activities Answer Key
How to Estimate the Recommended Daily Intake for Iron
Study Card 13 Answer Key
1. A well-balanced diet normally supplies just enough of these minerals to maintain health. It is easier and safer to
meet nutrient needs by selecting a variety of foods than by combining an assortment of supplements. Balance
2. Interactions among the trace minerals are common and often well coordinated to meet the body’s needs. For
example, several of the trace minerals support insulin’s work, influencing its synthesis, storage, release, and
3. Heme iron is the iron in foods that is bound to the hemoglobin and myoglobin proteins; it is found only in meat,
fish, and poultry. Nonheme iron is the iron in foods that is not bound to proteins, and is found in both plant-
8. The iron overload disorder known as hemochromatosis is caused by a genetic failure to prevent unneeded iron
in the diet from being absorbed. Research suggests that the hormone hepcidin supports iron homeostasis and its
9. Special proteins help the body absorb iron from food. The iron-storage protein ferritin captures iron from food
and stores it in the cells of the small intestine. When the body needs iron, ferritin releases some iron to an iron
transport protein called transferrin. If the body does not need iron, it is carried out when the intestinal cells are
shed and excreted in the feces; intestinal cells are replaced about every three to five days. Similarly, absorbed
Critical Thinking Questions
8
1. Explain how the different stages of iron deficiency can be identified based on clinical evidence.
2. What dietary factors contribute to health issues for clients who have hemochromatosis?
3. Describe how the process of recycling affects trace elements in the body.
4. What clinical conditions may account for the presence of goiter?
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5. Many individuals take mineral supplements to enhance body function. What potential health concerns should be
considered by an individual who is considering taking chromium supplements?
6. Explain the different mechanisms of the altered copper levels apparent in Wilson’s and Menkes disease states.
Answer Key
1. The first stage of iron deficiency is denoted by low ferritin levels, which represent iron stores in the body. The
second stage of iron deficiency is a result of altered levels of transport proteins. In this stage, serum iron levels
2. Hemochromatosis is a genetic disorder whereby the individual suffers from iron overload. Many foods in the
American diet are fortified with iron. Individuals may have difficulty in selecting foods, as their choices may be
limited by iron fortification. Since iron-deficiency anemia is the most prevalent type of anemia in the world,
3. The body has a series of recycling processes that help to regulate (recycle) trace elements in the body. Through
4. The presence of goiter, enlargement of the thyroid gland, can occur as a result of both iodine deficiency and
iodine excess. In individuals with decreased thyroid function (hypothyroidism), the presence of goiter is
5. Chromium’s effect on insulin metabolism should be considered if an individual is considering supplementation.
6. In Wilson’s disease, there is an increase in copper levels leading to adverse outcomes based on toxicity. Copper
IM Worksheet Answer Key
Worksheet 13-1: Mineral Overload Syndromes
1. No. Iron overload syndrome is not merely a consequence of taking in too much iron in the diet, although iron
poisoning via supplementation can lead to serious adverse effects, as can increasing iron load from multiple
Worksheet 13-2: Beyond the Goiter Belt
2. The “Goiter Belt” existed in the Great Lakes region and the plain states back in the 1900s.
4. There are 60 micrograms iodine per gram salt, which would equal 60 mg per 1000 g. Per
5. Minimal cost per person; see http://www.iccidd.org/pages/protecting-children/fortifying-salt/history-of-salt-
iodization.php to read about David Marine, the “father of iodized salt.”
7. Yes, pregnant woman are at risk for both deficiency and toxicity in terms of fetal development.
9. Yes.
10. No.
Worksheet 13-3: Chapter 13 Crossword Puzzle
Worksheet 13-4: Phytochemicals and Functional Foods (Internet Exercise)
242
Worksheet 13-1: Mineral Overload Syndromes
You are asked to provide information about mineral overload syndromes to your nutrition class.
In researching the topic, you understand that iron overload appears to be the most common type.
How would you answer the questions below? (Circle “Yes” or “No.”)
1. Can you get iron overload syndromes by merely ingesting too much
iron in your foods?
Yes
No
2. Can you get iron overload syndromes through genetic transmission?
Yes
No
3. Is there a difference between hemochromatosis and hemosiderosis?
Yes
No
7. Is there a difference in absorption between heme and non-heme
sources of iron?
Yes
No
8. If you eat a large amount of meat in your diet, will this lead to
decreased absorption of iron?
Yes
No
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Worksheet 13-2: Beyond the Goiter Belt
Research the following questions and be prepared to discuss your findings in a round table discussion format.
1. What are the incidence and prevalence of goiter?
2. Where did the “Goiter Belt” exist in the United States?
3. Why did salt become “iodized” in the United States?
7. Are pregnant women at risk for problems with iodine?
8. What lab tests should be assessed to determine whether or not a person has normal thyroid function?
Iodine
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Worksheet 13-3: Chapter 13 Crossword Puzzle
1
2
3
4
5
6
7
8
9
10
11
12
Across:
Down:
1. Named for their small quantity in the body (not
meant to diminish their significance)
6. Added to public drinking water to improve dental
health
8. Nutrient with roles in immune function,
11. Form of iron that is best absorbed; found only in
animal flesh (meat, fish, poultry)
12. Regular use of calcium and iron supplements may
impair absorption of the mineral _____.
2. Essential for iron metabolism and hemoglobin
synthesis
7. Essential part of thyroid hormones; also plays a role
in maintaining energy balance
10. Children with _____ deficiency are especially
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Worksheet 13-4: Phytochemicals and Functional Foods (Internet Exercise)
Click on Lycopene: an Antioxidant for Good Health to answer question 1.
1. Which of the following statements is accurate concerning lycopene?
a. Lycopene is produced in the body regardless of intake of food items.
b. Cooked or processed tomato products provide more lycopene to the body than fresh tomatoes.
Click on Functional Foods? to answer questions 2-4.
3. The action of some antibiotics can be affected by the ingestion of calcium-fortified orange juice.
a. True b. False
4. Another term that can be used interchangeably with “functional foods” is “phoods.”
a. True b. False
Click on Functional Foods Fact Sheet: Antioxidants to answer questions 5-8.
6. The prominent phytochemicals in cranberries can be categorized as phenols.
a. True b. False
7. Including whole grains in your diet can decrease the risk of developing diabetes.
a. True b. False
8. Selenium protects cells against free radical damage.
9. There are over 1000 substances that have phytochemical activity in food.
a. True b. False
