Transcript Chapter 12

The Trace Minerals
Trace Minerals
Iron, Zinc, Iodine, Selenium, Copper,
Manganese, Fluoride, Chromium,
Molybdenum
 Needed in minute quantities
 Toxicity may occur at intakes not far above
estimated requirement
 Found in a variety of foods

Iron

General information
 Most
of the body’s iron is in hemoglobin and
myoglobin
 Carries oxygen for use in energy metabolism
 Proteins assist with iron absorption, transport,
and storage
Iron - RDA

Men
8

mg/day
Women
 18
mg/day (19-50 yrs); 8 mg/d (51 +)
 Upper
Level: Adults: 45 mg/day
Iron - Major Functions
Carries oxygen
 Co-factor to enzymes involved in oxidationreduction reactions
 Part of electron carriers in electron transport
chain

Iron Recycled in the Body
Some losses
via sweat, skin,
and urine
Transferrin carries
iron in blood.
Some iron
delivered to
myoglobin
of muscle cells
Liver (and spleen) dismantles
red blood cells, packages
iron into transferrin, and
stores excess iron in
ferritin (and hemosiderin).
Some losses
if bleeding
occurs
Bone marrow incorporates
iron into hemoglobin of
red blood cells and stores
excess iron in ferritin
(and hemosiderin).
Iron-containing
hemoglobin in red
blood cells
carries oxygen.
Figure 13-3
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Iron - Deficiency





Worldwide, most common nutrient deficiency,
affects > 1 billion people
High risk: women in reproductive years, pregnant
women, infants & young children, teenagers
Blood loss may also lead to iron deficiency
Develops in stages
Iron-deficiency anemia severe depletion iron
stores
Normal and Anemic Blood Cells
Both size and color are normal in these
blood cells.
Blood cells in iron-deficiency anemia are
small (microcytic) and pale (hypochromic)
because they contain less hemoglobin.
Figure 13-4
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Table 13-1
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Iron - Toxicity
Toxicity from excess iron results in iron
overload
 More common in men
 Iron-containing supplements leading cause
of accidental poisoning in children

Major Food Sources
Red meats, fish, poultry sources of heme
iron & contain MFP factor, which enhance
iron absorption; shellfish, eggs
 Non-heme sources of iron include legumes,
iron-enriched grains
 Non-heme iron absorption increased with
MFP foods, Vitamin C

Heme and Nonheme Iron in Foods
Only foods derived from
animal flesh provide
heme, but they also
contain nonheme iron.
Key:
Heme
Nonheme
Heme accounts for about
10% of the average daily
iron intake, but it is well
absorbed (about 25%).
Nonheme iron accounts
for the remaining 90% but
it is less well absorbed
(about 17%).
All the iron in foods
derived from plants
is nonheme iron.
Figure 13-2
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When the label on a grain
product says “enriched,”
It means iron and several
B vitamins have been
added.
In-text Figure
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An old-fashioned iron skillet adds iron to foods.
In-text Figure
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Zinc

General information
 Required
as a cofactor by more than 100
enzymes; all cells contain zinc
RDA – Men: 11 mg/d; Women: 8 mg/d
 Upper level: Adults - 40 mg/d

Zinc - Major Functions
Part of many enzymes
 Involved in making genetic material and
proteins
 Involved in immune reactions
 Transport of Vitamin A
 Taste perception

Zinc - Deficiency
Severe growth retardation
 Hinders digestion & absorption, causing
diarrhea
 Impairs immune function
 Alters taste, causes anorexia, slows wound
healing

Zinc-Deficiency Symptoms—The Stunted Growth of Dwarfism
The boy on the
left is 17 years
old but is only
4 feet tall.
The man on the
right is an adult
of average
height.
Figure 13-7
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Zinc - Toxicity

Vomiting, diarrhea, headaches, other
symptoms
Zinc-Food Sources

Protein-containing foods: meats, fish,
poultry, whole grains, vegetables
Zinc is highest in protein-rich
foods such as oysters, beef,
poultry, legumes, and nuts.
In-text Figure
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Iodine

General information
 Part
of thyroid hormone that regulates body
temperature, metabolic rate, reproduction,
growth, and more

RDA - 2001
 Adults:
150 µg/day
 Upper level: 1.1 mg/day
Iodine - Deficiency
Simple goiter; cretinism
 Enlargement of thyroid gland, weight gain

Iodine - Toxicity
Enlargement of thyroid gland
 Especially damaging to developing fetus
 Upper limit: 1000 µg/day

Iodine - Food Sources
Ocean is world’s major source of iodine
 Iodized salt, seafood, bread, dairy products,
plants grown in iodine-rich soil

Only “iodized salt” has had iodine added.
In-text Figure
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Selenium, Copper, Manganese



Selenium – Antioxidant, works with Vitamin E;
deficiency associated with a heart disease; food
sources – seafood, meat, whole grains
Copper – Part of several enzymes, necessary for
absorption & use of iron; deficiency is rare; food
sources – legumes, whole grains, nuts, shellfish
Manganese – Involved in various metabolic
processes; deficiencies rare; food sources – nuts,
whole grains, leafy veggies
Fluoride
Major Functions: Makes bones stronger,
teeth resistant to decay
 Food Sources: Fluoridated water, tea, foods
prepared with fluoridated water, seafood
 Toxicity: Fluorosis (mottling of teeth)

U.S. Population with Access to Fluoridated Water through Public Water Systems
Key:
< 49%
50% – 74%
> 75%
Figure 13-10
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Chromium, Molybdenum
Chromium – Participates in carbohydrate
and lipid metabolism; present in a variety of
foods
 Molybdenum – Cofactor for several
enzymes; unknown deficiency; found in
legumes, cereals, organ meats

Iron Absorption
Iron in food
Mucosal cells in the
intestine store excess
iron in mucosal ferritin
(a storage protein).
If the body
does not
need iron
Iron is excreted in
shed intestinal cells.
If the body
needs iron
Mucosal ferritin releases iron to
mucosal transferrin (a transport
protein), which hands off iron to
another transferrin that travels
through the blood to the rest of
the body.
Figure 13-1
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This chili dinner provides several factors that may enhance iron
absorption: heme and non-heme iron and MFP from meat, nonheme
iron from legumes, and vitamin C from tomatoes.
In-text Figure
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Iron in Selected Foods
RDA for
women
19–50
RDA for
women
51+
RDA
for
men
IRON
Meats (red), legumes (brown),
and some vegetables (green)
make the greatest contributions
of iron to the diet.
Key:
Breads and cereals
Vegetables
Fruits
Milk and milk products
Legumes, nuts, seeds
Meats
Best sources per kcalorie
Figure 13-5
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Enteropancreatic Circulation of Zinc
Zinc in food
The pancreas uses
zinc to make
digestive enzymes
and secretes them
into the intestine.
Mucosal cells in
the intestine store
excess zinc in
metallothionein.
If the body
does not
need zinc
Zinc is excreted in
shed intestinal cells.
If the body
needs zinc
Metallothionein releases
zinc to albumin and
transferrin for transport
to the rest of the body.
Figure 13-6
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Micrograms RAE
Zinc in Selected Foods
Food
Serving size (kcalories)
RDA
for
men
RDA
for
women
ZINC
Label
Meat, fish, and poultry
(red) are
concentrated sources of zinc.
Milk (white) and legumes
(brown) contain some zinc.
Key:
Breads and cereals
Vegetables
Fruits
Milk and milk products
Legumes, nuts, seeds
Meats
Best sources per kcalorie
Figure 13-8
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Cobalt with Vitamin B 12
The intricate vitamin B12 molecule
contains one atom of the mineral
cobalt. The alternative name for
vitamin B12 , cobalamin, reflects
the presence of cobalt in its
structure.
Figure 13-12
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Practice planning meals with varying
energy needs to meet recommended
intakes of several minerals.
Click to view
animation.
Animation
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Phytochemicals
and Functional
Foods
In-text Figure
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Table H13-1
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(cont.)
Table H13-1(2)
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Nature offers a variety of functional foods that
provide us with many health benefits.
In-text Figure
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An Array of Phytochemicals in a Variety of Fruits and Vegetables
Broccoli and broccoli sprouts contain an abundance of the
cancer-fighting phytochemical sulforaphane.
The phytochemical resveratrol found in grapes (and nuts)
protects against cancer by inhibiting cell growth and against
heart disease by limiting clot formation and inflammation.
The flavonoids in cocoa and chocolate defend
against oxidation and reduce the tendency of
blood to clot.
Fig. H13-1 (1)
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An Array of Phytochemicals in a Variety of Fruits and Vegetables (cont’d)
An apple a day—rich in flavonoids—may protect against
lung cancer.
The ellagic acid of strawberries may inhibit certain types of
cancer.
Tomatoes, with their abundant lycopene, may defend against
cancer by protecting DNA from oxidative damage.
Spinach and other colorful vegetables contain
the carotenoids lutein and zeaxanthin, which
help protect the eyes against macular
degeneration.
Fig. H13-1 (2)
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An Array of Phytochemicals in a Variety of Fruits and Vegetables (cont’d)
The phytoestrogens of soybeans seem to starve cancer
cells and inhibit tumor growth; the phytosterols may
lower blood cholesterol and protect cardiac arteries.
The monoterpenes of citrus fruits (and cherries) may
inhibit cancer growth.
Flaxseed, the richest source of lignans,
may prevent the spread of cancer.
Fig. H13-1 (3)
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An Array of Phytochemicals in a Variety of Fruits and Vegetables (cont’d)
Garlic, with its abundant organosulfur compounds, may
lower blood cholesterol and protect against stomach
cancer.
The flavonoids in black tea may protect against heart disease,
whereas those in green tea may defend against cancer.
Blueberries, a rich source of flavonoids,
improve memory in animals.
Fig. H13-1 (4)
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Functional foods currently on the market promise to “enhance mood,”
“promote relaxation and good karma,” “increase alertness,” and
“improve memory,” among other claims.
In-text Figure
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