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Chapter 13 – The Trace Minerals
Class Preparation and Assignment Materials for Chapter 13
This chapter of the instructor’s manual includes the following class preparation tools:
 Sample answers to the “Everybody Has a Story” critical thinking questions from the text
 A description and expected learning outcomes for the Diet & Wellness + activity in the text
 A list of chapter learning objectives
 A detailed chapter outline
 “Q and As” for further discussion of related topics
This chapter also includes the following student activities/assignments1:
 Worksheet 13-1: Can You Find the Trace Minerals?
 Worksheet 13-2: Iron in the Herbivore and Omnivore Diets
 Worksheet 13-3: A Beautiful Blue Mineral
Suggested Answer Key for In-Text “Everybody Has a Story” Questions1
Living Life As an “Iron Man” – Critical Thinking Part 1 (page 554):
How would having hemochromatosis or another condition that requires you to be careful about how much iron you
eat change your daily life?
A few changes in daily life are necessary for a person with hemochromatosis. For instance, regularly scheduled
phlebotomies will be a usual routine; searching food items for iron content will be common; and avoiding iron-rich
foods will be automatic. I think an individual with hemochromatosis should be alert when considering exercise
routines and if she decides to become pregnant.
According to Figure 13.2 Food Sources of Iron (page 557), many of the dietary sources of iron considered adequate
(5-23 mg per 100 g foodstuff) are food items rarely consumed by most individuals. For instance, clams, turkey
giblets, cooked white beans, lentils, liver sausage, beef liver, and pumpkin seeds are food items easily identified and
avoided by an individual like David with hemochromatosis. The food items containing iron that might be
problematic for a person trying to minimize dietary iron might be: enriched flake cereal, spinach, chick peas, beef,
and mushrooms (5 foods in this selection). One can find low-iron cereals, but for David, spinach, hummus, beef, and
mushrooms should probably be avoided. Otherwise, a diet for an individual with hemochromatosis should be rather
simple to follow as long as the few iron-rich foods are regularly avoided.
If you found out that you had hemochromatosis or a similar disease, how would you cope with the costs and time
commitment needed for treatment?
If I discovered I had hemochromatosis I think I would react similarly to David: choose more nonheme food items,
exercise more, and not be thrilled about being a “guinea pig” for phlebotomists-in-training. I might become more
active in fundraising for others with hemochromatosis such that the fees for frequent phlebotomies would not drain
their finances. In addition, I would encourage David and others with hemochromatosis to share their choices with
one another and help each other succeed, too.
Critical Thinking Part 2 (page 559):
You now know more about what causes hemochromatosis. Recall David, the graduate student you read about in this
chapter’s Everybody Has a Story. Can you now explain in some detail how hemochromatosis alters normal iron
regulation in his body?
Iron is stored intracellularly as ferritin and hemosiderin. Ferritin synthesis is regulated according to iron availability
by a system of cytoplasmic binding proteins (IRP-1 and -2) and a noncoding iron regulatory element on mRNA
(IRE). When iron is abundant (as in hemochromatosis), iron blocks binding and promotes increased synthesis of
ferritin. Ferritin is also the storage form of iron and tends to accumulate in the parenchymal cells in the periportal
areas of the liver. With time, and excessive iron absorption, these parenchymal cells of the liver are destroyed and
1
By Susan Edgar Helm of Pepperdine University
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228
replaced with fibrous tissue, leading to a condition known as hepatic cirrhosis. The destruction of the liver cells from
too much iron being deposited releases the liver enzymes, alanine aminotransferase and aspartate aminotransferase.
Once the liver enzymes are released, they are detected at high levels in the bloodstream.
Why would he and his wife be contemplating having their baby tested for this disease?
A genetic test is available to detect hereditary hemochromatosis in infants. David has a condition called hereditary
hemochromatosis that was only discovered in 1996. It is now known that the increased iron absorption of
hemochromatosis is due to a defect in the gene (HFE) that codes for one of the transport proteins or the hormone
hepcidin involved in regulating intestinal iron transport. The HFE gene has a single mutation that results in the body
being unable to sense its iron stores, resulting in an increased iron absorption. Hemachromatosis is a progressive
disease, meaning that the intestine continues to absorb as much iron as it can and floods the blood with high levels
of iron. Over time, blood iron overload and tissue iron saturation can occur with secondary effects that may or may
not be manageable. Iron accumulates in the joints, liver, heart, and pancreas, causing cirrhosis of the liver,
congestive heart failure, and diabetes in some individuals. With knowledge about this genetic condition, earlier
treatment strategies can be used, possibly preventing permanent liver damage or heart failure and death by 50 years
of age.
If you had this condition, would you have your children tested?
If I knew I had the genetic condition of hereditary hemochromatosis, then I would have all my children tested. If the
test for hereditary hemochromatosis was positive for any one or all of my children, then it would allow me to change
their diet, use drugs that bind iron, and schedule regular phelebotomies to lower blood iron for prevention of iron
buildup in the liver. Also, knowing about the genetic condition within the family would allow me to keep abreast of
the latest literature for new preventive measures for hereditary hemochromatosis and to pass this information to my
children’s spouses and, of course, the following generations.
Critical Thinking Part 3 (page 579):
You have now learned why consumption of all the essential trace minerals is critical for health. You have also
learned about some conditions, such as hemochromatosis, that require individuals (like David) to make sure they do
not consume too much of particular nutrients (like iron). Now that you know why David must limit his intake of iron,
can you explain how his dietary choices could impact his status for other nutrients in his body?
If high-iron cereals, beef, hummus, and spinach are the specific foods avoided by an individual with
hemochromatosis, then few other nutrients will be affected by David’s food choices. Since beef is a primary source
of heme iron, then a considerable amount of iron will be unavailable if David chooses not to consume beef. Some
dietary factors are known to enhance dietary iron absorption and should be consumed less by David: sugars,
especially fructose and sorbitol; and any acids, such as citric acid, lactic acid, and tartaric acid. Mucin (gastroferrin),
a small protein synthesized by the gastric and intestinal cells, chelates iron and increases its absorption as well.
Some dietary components will inhibit dietary absorption of iron and should be included in dietary planning for an
individual with hemachromatosis: polyphenols like tannins in teas and coffees; oxalates in chard, berries, chocolate,
and teas; phytates in whole grains and legumes; phosvitin, a protein in egg yolks; and finally some specific nutrients
that bind iron, namely calcium, manganese, and nickel (perhaps a daily chocolate-covered Tums® would be helpful
to reduce iron absorption!).
Overview of Chapter 13’s Diet & Wellness + Activity2
Description of the assignment: Iron deficiency is one of the most common nutrient deficiencies in the world. In the
United States, women between the ages of 19 and 50 years often suffer from iron deficiency, and their dietary intake
of the trace mineral iron falls very short of the RDA of 18 mg. It is important for women to identify nutrient-dense
sources of easily absorbed iron.
College students may choose a vegetarian lifestyle and may require as much as 50% more of the RDA for zinc. In
this activity students will analyze their intakes of iron and zinc.
2
By Prithiva Chanmugam and Judy Myhand of Louisiana State University
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229
Expected learning outcomes: Learning objectives met (or partially met) by this activity:
Identify significant food sources for each trace mineral.
Chapter Learning Objectives
The student will be able to:
1.
2.
3.
4.
5.
6.
Describe the structure and major functions of each trace mineral.
Identify significant food sources for each trace mineral.
Outline how each trace mineral is absorbed, metabolized, and regulated in the body.
Discuss the deficiency and toxicity signs and symptoms for each trace mineral and the existing corresponding
disease states.
Discuss the increased needs for specific trace minerals for vegetarians and athletes.
List several additional elements that seem to have functions within the body.
Lecture Presentation Outline3
I.
What Do the Trace Minerals Have in Common?
TA 18 (Fig. 12.1) & 167 (Table 13.1), Worksheet 13-1
A. Overview
1. 8 essential nutrients - iron, copper, iodine, selenium, chromium, manganese, molybdenum, and zinc
2. < 100 mg/day needed
B. Regulation of Trace Minerals in the Body
1. Bioavailability influenced by:
a. Genetics
b. Life stage
c. Nutritional status
d. Nutrient interactions
2. Absorbed in small intestine
3. Circulated in blood to the liver
4. Individual trace minerals are regulated by either intestinal absorption, the kidneys, or the liver
5. Deficiencies & toxicities rare - Except genetic disorders, excessive supplementation & environmental
exposure
C. Trace Minerals Act as Cofactors and Prosthetic Groups and Provide Structure
TA 168 (Fig. 13.1)
1. Cofactors
2. Metalloenzyme - Components of nonenzymatic molecules
3. Provide structure to mineralized tissues
II. Iron (Fe)—The Body’s Transporter of Oxygen
A. Iron Is in Both Plant and Animal Foods
TA 169 (Fig. 13.2); Worksheet 13-2
1. Heme iron
a. Bound to a heme group
b. Shellfish, beef, poultry, organ meats
c. Makes up - Hemoglobin, myoglobin, cytochromes
2. Nonheme iron
a. Green leafy vegetables, mushrooms, legumes, enriched grains
b. ~85% of dietary iron intake
B. Many Factors Influence Iron Bioavailability
1. Influenced by:
a. Form in food - Heme, nonheme, ferric, ferrous
b. Iron status of the person
c. Presence/absence of other dietary components in the meal
2. Vitamin C and “Meat Factor” Increase Nonheme Iron Absorption
3
By Lisa Esposito, M.S., R.D., C.S.S.D., L.D.N. (Chicago, IL)
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230
a.
b.
Vitamin C & stomach acid - Convert ferric to ferrous iron
Meat factor
1. Compound in meat, poultry, seafood
2. Meat + nonheme iron
3. Phytates and Polyphenols Decrease Iron Bioavailability
a. Chelators - Bind to iron in intestine and make difficult to absorb
b. Phytates - In vegetables, grains, seeds
c. Polyphenols - Some vegetables, tea, coffee, red wine
C. Iron Absorption Is Tightly Regulated
1. Iron Absorption
a. Transport
1. Across brush border & basolateral membrane
2. Heme iron - Chemical modification not needed
3. Nonheme iron - Reduced to ferrous form
4. Hepsidin - Hormone that regulates synthesis of transport proteins
5. Ferritin
b. Hereditary Hemochromatosis
1. Defect in one of a number of genes that code for transport proteins required for intestinal iron
absorption
2. Symptoms: Arthritis, chronic fatigue, lack of normal menstruation, abnormal liver function
3. Treatment
a. Frequent removal of blood
b. Avoidance of iron-containing & vitamin C supplements
c. Dietary
c. Iron Deficiency Increases Iron Absorption
TA 170 (Fig. 13.3)
1. Adequate or excess iron - Body normally decreases production of transport proteins
2. Iron deficiency
a. Hepsidin increases production of transport proteins
b. Decreases ferritin production
2. Ferritin and Hemosiderin Store Excess Iron
TA 171
a. Transferrin - Delivers iron to body cells
b. Transferrin receptors
c. Iron storage compounds
1. Ferritin - Main storage form
2. Hemosiderin - Long-term storage
D. Iron Is a Component of Heme and Nonheme Proteins
1. Oxygen and Carbon Dioxide Transport: Hemoglobin
TA 69 (Fig. 5.5)
a. Most abundant protein in red blood cells
b. 4 protein subunits + 4 iron-containing heme groups
c. Delivers oxygen to cells
d. Picks up carbon dioxide
2. Oxygen Reservoir: Myoglobin
a. Found in muscle cells
b. Heme group + protein subunit
c. Releases oxygen to cells when needed for: ATP production, muscle contraction
3. Cellular Energy Metabolism
a. Cytochromes
1. Heme-containing complexes
2. Function in electron transport chain
3. Allow conversion of ADP to ATP
b. Iron as cofactor
1. Electron transport chain
2. Citric acid cycle
3. Gluconeogenesis
4. Iron—A Cofactor for Detoxifying and Antioxidant Enzymes
a. Cytochrome P450 enzymes
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231
b. Cofactor for antioxidant enzymes
c. Protects DNA, cell membranes, proteins
d. Cofactor for enzyme to make DNA
E. Iron Deficiency Causes Anemia and Much More
1. Overview
a. Most common nutritional deficiency
b. At-risk groups: Infants, growing children, pregnant women
c. Pica
2. Mild Iron Deficiency Leads to Fatigue and Other Problems - Signs:
a. Fatigue
b. Impaired physical work performance
c. Behavioral abnormalities
d. Impaired intellectual abilities in children
e. Body temperature regulation
f. Influences immune system
g. Detecting Mild Iron Deficiency
1. Serum ferritin concentration - < 12 micrograms/L
2. Total iron-binding capacity - > 400 micrograms/dL
3. Serum transferrin saturation - < 16%
3. Severe Iron Deficiency Causes Microcytic, Hypochromic Anemia
a. Microcytic, hypochromic anemia - Small, pale red blood cells
b. Body is unable to produce enough heme
c. Decreased ability to carry oxygen
d. Decreased ATP synthesis
e. Detecting Severe Iron Deficiency
1. Hemoglobin concentration - Men < 130 g/L, women < 120 g/L
2. Hematocrit - Men < 39%, women <36%
4. Basics of Iron Supplementation
a. When diet alone is not enough
b. Ferrous iron
1. Best absorbed
2. Other terms: Ferrous fumarate, ferrous sulfate, ferrous gluconate
c. Ferric iron
F. Iron Toxicity Can Be Fatal
1. Medicinal or supplemental iron overdoses
2. Most common cause of childhood poisoning
3. Symptoms - Vomiting, diarrhea, constipation, black stools
4. Can result in death
5. Excess deposited in liver, heart, muscles
G. Recommended Intakes for Iron
1. Requirements higher for:
a. Pregnant women
b. Periods of rapid growth & development
2. RDAs
a. Men = 8 mg/day
b. Women = 18 mg/day (8 mg/day post-menopausal)
c. Pregnancy = 27 mg/day
3. UL - 45 mg/day
4. Special Recommendations for Vegetarians and Endurance Athletes
a. Vegans
1. Needs are 80% higher
2. Iron supplements
b. Endurance athletes
1. Increased blood loss in feces/urine
2. Chronic rupture of red blood cells in feet
3. Needs are 70% higher
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III. Copper (Cu)—Cofactor in Redox Reactions
A. Organ Meats are Excellent Sources of Copper
1. Forms - Cupric, cuprous
2. Organ meats, shellfish, whole-grain products, mushrooms, nuts, legumes
3. Bioavailability decreases with: Antacids, excessive iron intake
4. Working Toward the Goal: Increasing Trace Mineral Intake via Nuts and Seeds
a. 2015 DGAs & MyPlate - Consume a variety of nuts & seeds in moderation
b. Add slivered almonds to steamed vegetables
c. Add cashews to stir-fry
d. For snacks, try sunflower seeds
e. Try toasted hazelnuts on oatmeal
B. Excess Copper Is Eliminated in Bile
1. Absorbed in small intestine & stomach
2. Influenced by Cu status
3. Ceruloplasmin
4. Excess incorporated into bile & eliminated in feces
C. Copper Is Involved in Reduction-Oxidation (Redox) Reactions
1. Cofactor for at least 9 metalloenzymes in redox reactions
2. ATP production
3. Iron metabolism
4. Neural function
5. Antioxidant function
6. Connective tissue synthesis
7. Cytochrome c oxidase
8. Superoxide dismutase
D. Copper Deficiency and Toxicity Are Rare
1. Deficiency
a. Hospitalized patients & preterm infants
b. Antacids
c. Signs & Symptoms
1. Defective connective tissue
2. Anemia
3. Neural problems
2. Toxicity - Rare
3. Recommended Intakes for Copper
a. RDA - 900 micrograms/day
b. UL - 10 mg/day
TA 172 (Fig. 13.6)
IV. Iodine (Iodide; I)—An Essential Component of the Thyroid Hormones
A. Marine Foods Supply Iodine Naturally
1. Good sources: Ocean fish, mollusks, seaweed
2. Dairy products - Iodine used in milk processing
3. Iodized salt
B. Goitrogens Inhibit Iodine Utilization
1. Iodine is absorbed in small intestine & stomach
2. Taken up by thyroid gland
3. Thyroid-stimulating hormone regulates uptake
4. Goitrogens
C. Iodine Is a Component of Thyroid Hormones
1. Component of:
a. Thyroxine (T4)
b. Triiodothyronine (T3)
2. Regulates energy metabolism, growth, development
D. Iodine Deficiency Causes Cretinism and Goiter
TA 173 (Fig. 13.7)
TA 174 (Fig. 13.8)
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233
1.
Signs of deficiency
a. Severe fatigue
b. Lethargy
2. Fetal Iodine Deficiency: Cretinism
3. Childhood and Adult Iodine Deficiency: Goiter
4. Recent Concern about Iodine Deficiency
a. Current - Public Health working to eradicate goiter internationally
b. Recommended supplementation for pregnant women
5. Iodine Deficiency and Iodination of Salt
a. 1920s - “Goiter Belt”
b. Statewide campaigns
c. Started providing iodized salt to children
d. Goiter almost eliminated
E. Recommended Intakes for Iodine
1. Hypothyroidism
2. Hyperthyroidism
3. Formation of goiters
4. RDA - 150 micrograms/day
5. UL - 1,100 micrograms/day
V. Selenium (Se)—A Mineral with Antioxidant Functions
A. Nuts, Seafood, and Meats Are Rich in Selenium
1. Nuts
2. Seafood and meats
B. Selenium Is Incorporated into Selenoproteins
1. Most Se enters blood
2. Incorporated into selenomethionine
3. Makes selenoproteins
4. Stored in muscles
5. Maintenance of Se through excretion in urine - controlled by the kidneys
C. Selenium Is an Important Antioxidant
1. 14 selenoproteins
2. Glutathione peroxidases
3. Redox functions
4. Thyroid function
5. Vitamin C metabolism
6. Role in immune function
D. Selenium Deficiency Results in Keshan Disease
1. Deficiency - Keshan disease
2. Toxicity
a. Garlic-like odor of breath
b. Nausea, vomiting, diarrhea
c. Brittleness of teeth & fingernails
3. RDA - 55 micrograms/day
4. UL - 400 micrograms/day
TA 175 (Fig. 13.9)
Q&A 13-1
VI. Chromium (Cr)—Implicated in Glucose Homeostasis
A. Chromium Content of Foods Depends on Chromium Content of Soil
1. Whole grains, fruits/veg, processed meats, beer, wine
2. Bioavailability affected by:
a. Vitamin C
b. Acidic medications
c. Antacids
3. Transported in blood to liver
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234
4. Excess excreted by the kidneys in urine & feces
B. Chromium May Be Involved in Glucose Homeostasis
1. Regulates insulin
2. Growth & development - Lab animals
a. Increases lean mass
b. Decreases fat mass
3. Ergogenic aid - Chromium picolinate
C. Chromium Deficiency and Toxicity Are Rare
1. Deficiency
a. Hospitalized patients
b. Elevated blood glucose
c. Decreased insulin sensitivity
d. Weight loss
2. Toxicity
a. Rare
b. Industrially released chromium
D. Recommended Intakes for Chromium
1. AIs - 20-35 micrograms/day
2. No ULs
Q&A 13-2
VII. Manganese (Mn)—Important for Gluconeogenesis and Bone Formation
A. Plants Foods Are the Best Sources of Manganese
1. Whole grains, pineapples, nuts, legumes, dark green leafy vegetables, water
2. <10% absorbed
3. Excess incorporated into bile by the liver & excreted in feces
4. Functions of manganese
a. Cofactor for metalloenzymes
b. Gluconeogenesis
c. Bone formation
d. Energy metabolism
e. Cofactor for superoxide dismutase
B. Severe Manganese Deficiency Causes Weak Bones and Slow Growth
1. Deficiency
a. Rare
b. Scaly skin, poor bone formation, growth faltering
2. Toxicity
a. Rare
b. Mining - environmental exposure
c. Liver disease
d. High water levels
3. Recommended intakes for manganese
a. AIs
1. Men = 2.3 mg/day
2. Women = 1.8 mg/day
b. UL - 11 mg/day
VIII. Molybdenum (Mo)—Required in Very Small Quantities
A. Legumes, Nuts, and Grains Provide Molybdenum
1. Molybdenum: dietary sources
a. Food content depends on soil
b. Legumes, grains, nuts
c. Absorbed in intestine
d. Circulated to liver via blood
2. Functions of molybdenum
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235
a. Redox reactions
b. Cofactor for several enzymes
c. Metabolism of: Sulfur-containing amino acids
d. DNA & RNA
e. Detoxifying drugs in liver
B. Molybdenum Deficiency Is Exceedingly Rare
1. Deficiency - Rare
2. Toxicity
a. No known effects in humans
b. Animals - disrupts reproduction
3. RDA - 45 micrograms/day
4. UL - 2,000 micrograms/day
IX. Zinc (Zn)—Involved in RNA Synthesis and Gene Expression
A. Zinc Is Found in Shellfish, Organ Meats, and Dairy Foods
1. Sources: Shellfish, meat, dairy, legumes, chocolate, fortified cereals/grains
2. Bioavailability influenced by:
a. Phytates
b. Iron
c. Calcium
d. Animal sources
e. Acidic substances
B. Zinc Absorption Is Regulated Similar to Iron
1. Requires proteins to:
a. Transport zinc across the brush border into enterocyte - Metallothionine
b. Bind zinc within cell
2. Excess excreted in feces
3. Genetic influences
4. Acrodermatitis Enteropathica
a. Genetic abnormality
b. Zinc deficiency even with adequate amounts of dietary zinc
c. Supplementation
d. Infants - Growth failure, red/scaly skin, diarrhea
e. Human Genome Project
C. Zinc Is Involved in RNA Synthesis and Gene Expression
1. Cofactor
2. RNA synthesis
3. Alcohol metabolism
4. Stabilizes proteins that regulate gene expression - Zinc fingers
5. Antioxidant
6. Stabilizes cell membranes
D. Vegetarians May Need Additional Zinc
1. Deficiency
a. Decreases appetite
b. Increases morbidity
c. Decreases growth
d. Skin irritations, diarrhea, delayed sexual maturation
2. Toxicity
a. Supplements
b. Poor immune function
c. Depressed levels of HDL
d. Impaired copper status
e. Nausea, vomiting, loss of appetite
3. Recommended intakes for zinc
a. RDAs
TA 176 (Fig. 13.11)
Q&A 13-3
TA 177 (Fig. 13.11)
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236
b.
1. Men = 11 mg/day
2. Women = 8 mg/day
3. Vegetarians (vegans) - Consume up to 50% more zinc than nonvegetarians
UL - 40 mg/day
X. Fluoride (F-)—Nonessential Mineral That Strengthens Bones and Teeth
A. Many Communities Fluoridate Their Water
1. Not an essential nutrient
2. Potatoes, tea, legumes, fish w/bones, toothpaste, added to drinking water
3. American Dental Association - Fluoridation 1-2 ppm
4. Absorbed via small intestine
5. Circulates in blood to liver & then teeth & bone
6. Excess excreted by the kidneys via urine
B. Fluoride Strengthens Bones and Teeth
1. Part of bone & teeth matrix
2. Stimulates maturation of osteoblasts
3. Topical application decreases bacteria in mouth - Fewer cavities
C. Fluoride Toxicity Results in Fluorosis
1. Deficiency - None known
2. Toxicity
a. GI upset, excessive production of saliva, watery eyes, heart problems, coma
b. Dental fluorosis
c. Skeletal fluorosis
3. AIs
a. Men = 4 mg/day
b. Women = 3 mg/day
4. UL - 10 mg/day
XI. Are There Other Important Trace Minerals?
A.
B.
C.
D.
E.
F.
Worksheet 13-3
Nickel
Aluminum
Silicon
Vanadium
Arsenic
Boron
XII. Integration of Functions and Food Sources
TA 178
Q and As
Q&A 13-1
Question:
I would like to take a selenium supplement, but there are several choices. How is one different from the others, and
which one should I take?
Answer:
Sodium selenite and sodium selenate are inorganic forms of selenium. Sodium selenate is almost completely
absorbed, but much of it is excreted in the urine. Sodium selenite is only about 50% absorbed, but is better retained
than sodium selenate. Selenomethionine, an organic form of selenium, is about 90% absorbed. Presently, there is
little consensus among nutritionists that one form of selenium supplement is better than the others.
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237
Q&A 13-2
Question:
Would taking chromium picolinate supplements help me build muscle mass and lose fat?
Answer:
Probably not. In general, controlled clinical studies that have used the “gold standards” for measuring body
composition (such as dual energy x-ray absorptiometry) have not shown a beneficial effect of chromium
supplementation on body composition.
Q&A 13-3
Question:
I have heard that taking zinc lozenges can help prevent the common cold. Is this true?
Answer:
Although a handful of studies have suggested that taking zinc lozenges might slightly decrease the duration of a
cold, most controlled intervention trials do not support this health claim. In addition, consuming zinc supplements as
directed often results in zinc intakes well above the Tolerable Upper Intake Levels (ULs). Thus, they are generally
not recommended.
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Worksheet 13-1: Can You Find the Trace Minerals?
What is a trace mineral?
Circle the minerals below that are essential trace minerals. Draw a line through the names of any minerals
you find that are not trace minerals.
B
E
A
M
M
E
U
S
P
F
O
D
M
Q
U
X
P
D
E
G
S
E
L
E
N
I
U
M
O
T
Z
I
N
C
E
L
L
I
T
O
N
T
H
E
M
L
O
U
N
T
A
H
I
N
P
O
V
E
R
T
H
E
H
I
F
L
L
S
A
R
N
D
E
H
V
E
R
Y
W
H
E
R
E
U
G
O
T
O
P
L
E
A
O
S
R
A
S
E
F
D
T
O
R
M
E
M
E
T
Y
O
U
S
E
T
A
T
K
L
E
C
A
L
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239
Worksheet 13-2: Iron in the Herbivore and Omnivore Diets
David successfully lives with his medical condition, hemochromatosis. David is quite aware of the two forms of iron
found in foods: heme iron contained in meat and nonheme iron contained in plants and supplements. Calcium is the
only known substance that can impair the absorption of both heme and nonheme iron; hence, dairy products are
helpful for David to complement his diet without heme-filled meat products. Tannin (coffee, tea, chocolate), fiber,
eggs, and oxalates impair absorption of nonheme iron. It would be helpful for David to limit consumption of vitamin
C, alcohol, and simple carbohydrates, which enhance the absorption of iron, in order to avoid excess iron absorption.
An individual, like David, living with liver disease as a result of his hemochromatosis must especially be cautious
about consuming certain foods. The bioavailability of iron is complex, which means he must choose wisely to enjoy
an adequate, balanced, and healthy diet.
You can determine whether David necessarily needs to choose between an herbivorous or omnivorous diet by
completing the table provided below. Use the table to plan two balanced meals that each provide no more than
1/3 of David’s RDA for iron, one including both animal and plant foods and the other including only plantderived foods. To complete the table exercise, you may need to use Figure 13.2 in your textbook and perhaps
Internet sources of iron content in food items (e.g., http://www.nal.usda.gov/fnic/foodcomp/search/).
Table: Two Low-Iron Meals as an Omnivore and as an Herbivore
Food Items
Dinner as an Omnivore
Dinner as an Herbivore
Meat/alternate
Fruit
Vegetable
Vegetable
Grain
Beverage
Dessert
Questions:
1. Was it difficult to create the meals as an omnivore or herbivore?
2.
Does David need to choose a specific dietary lifestyle? Why or why not?
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240
Worksheet 13-3: A Beautiful Blue Mineral
Cobalt is such a stunning blue mineral!
1. How is cobalt consumed?
2. Is cobalt re-cycled?
3. Why do we need only trace amounts?
4. Explain how cobalt is essential for protein metabolism and DNA synthesis.
© 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a
license distributed with a certain product or service or otherwise on a password-protected website for classroom use.