The Trace Minerals

1
The Trace Minerals

• Chapter 13

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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

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Iron

• General information
• Most of the bodys iron is in hemoglobin and
  myoglobin
  
• Carries oxygen for use in energy metabolism
• Proteins assist with iron absorption, transport,
  and storage
  

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Iron - RDA

• Men
• 8 mg/day
• Women
• 18 mg/day (19-50 yrs) 8 mg/d (51 )
• Upper Level Adults 45 mg/day

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Iron - Major Functions

• Carries oxygen
• Co-factor to enzymes involved in
  oxidation-reduction reactions
  
• Part of electron carriers in electron transport
  chain
  

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Figure 13-3Page 441
Iron Recycled in the Body
Some losses via sweat, skin, and urine
Transferrin carries iron in blood.
Some iron delivered to myoglobin of muscle cell
s
Liver (and spleen) dismantles red blood cells, pa
ckages iron into transferrin, and stores excess
iron in
ferritin (and hemosiderin).
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 c
arries oxygen.
Some losses if bleeding occurs
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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

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Figure 13-4Page 443
Normal and Anemic Blood Cells
Blood cells in iron-deficiency anemia are
small (microcytic) and pale (hypochromic)
because they contain less hemoglobin.
Both size and color are normal in these
blood cells.
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Table 13-1Page 458
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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
  

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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

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Figure 13-2Page 440
Heme and Nonheme Iron in Foods
Only foods derived from animal flesh provide hem
e, but they also
contain nonheme iron.
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 non
heme iron.
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In-text Figure Page 445
When the label on a grain product says enriched,
It means iron and several B vitamins have bee
n
added.
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In-text Figure Page 447
An old-fashioned iron skillet adds iron to foods.
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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

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Zinc - Major Functions

• Part of many enzymes
• Involved in making genetic material and proteins
• Involved in immune reactions
• Transport of Vitamin A
• Taste perception

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Zinc - Deficiency

• Severe growth retardation
• Hinders digestion absorption, causing diarrhea
• Impairs immune function
• Alters taste, causes anorexia, slows wound healing

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Figure 13-7Page 449
Zinc-Deficiency SymptomsThe Stunted Growth of
Dwarfism
The man on the right is an adult of average
height.
The boy on the left is 17 years old but is only

4 feet tall.
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Zinc - Toxicity

• Vomiting, diarrhea, headaches, other symptoms

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Zinc-Food Sources

• Protein-containing foods meats, fish, poultry,
  whole grains, vegetables

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In-text Figure Page 449
Zinc is highest in protein-rich
foods such as oysters, beef, poultry, legumes, an
d nuts.
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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

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Iodine - Deficiency

• Simple goiter cretinism
• Enlargement of thyroid gland, weight gain

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Iodine - Toxicity

• Enlargement of thyroid gland
• Especially damaging to developing fetus
• Upper limit 1000 µg/day

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Iodine - Food Sources

• Ocean is worlds major source of iodine
• Iodized salt, seafood, bread, dairy products,
  plants grown in iodine-rich soil

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In-text Figure Page 452
Only iodized salt has had iodine added.
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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

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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)

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Figure 13-10Page 456
U.S. Population with Access to Fluoridated Water
through Public Water Systems
Key

50 74
75
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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

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Figure 13-1Page 439
Iron Absorption
Iron in food
If the body does not need iron
Mucosal cells in the intestine store excess iron
in mucosal ferritin
(a storage protein).
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.
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In-text Figure Page 441
This chili dinner provides several factors that
may enhance iron absorption heme and non-heme ir
on and MFP from meat, nonheme iron from legumes,
and vitamin C from tomatoes.
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Figure 13-5Page 446
Iron in Selected Foods
RDA for women 1950
RDA for women 51
IRON Meats (red), legumes (brown), and some vege
tables (green) make the greatest contributions o
f iron to the diet.
RDA for men
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Figure 13-6Page 448
Enteropancreatic Circulation of Zinc
Zinc in food
If the body does not need zinc
Mucosal cells in the intestine store excess zinc
in
metallothionein.
Zinc is excreted in shed intestinal cells.
The pancreas uses zinc to make digestive enzymes

and secretes them into the intestine.
If the body needs zinc
Metallothionein releases zinc to albumin and tra
nsferrin for transport
to the rest of the body.
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Figure 13-8Page 450
Zinc in Selected Foods
Micrograms RAE
Food Serving size (kcalories)
RDA for men
RDA for women
ZINC Meat, fish, and poultry (red) are concentra
ted sources of zinc. Milk (white) and legumes (b
rown) contain some zinc.
Label
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Figure 13-12Page 458
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.
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Animation
Practice planning meals with varying energy needs
to meet recommended intakes of several minerals.
Click to view animation.
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In-text Figure Page 465
Phytochemicals and Functional Foods
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Table H13-1Page 466
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Table H13-1(2)Page 466
(cont.)
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In-text Figure Page 467
Nature offers a variety of functional foods that
provide us with many health benefits.
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Fig. H13-1 (1)Page 468
An Array of Phytochemicals in a Variety of Fruits
and Vegetables
Broccoli and broccoli sprouts contain an
abundance of the cancer-fighting phytochemical su
lforaphane.
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.
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Fig. H13-1 (2)Page 468
An Array of Phytochemicals in a Variety of Fruits
and Vegetables (contd)
An apple a dayrich in flavonoidsmay 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 oxi
dative damage.
Spinach and other colorful vegetables contain
the carotenoids lutein and zeaxanthin, which
help protect the eyes against macular
degeneration.
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Fig. H13-1 (3)Page 468
An Array of Phytochemicals in a Variety of Fruits
and Vegetables (contd)
The phytoestrogens of soybeans seem to starve
cancer cells and inhibit tumor growth the phytos
terols may lower blood cholesterol and protect ca
rdiac arteries.
The monoterpenes of citrus fruits (and cherries)
may
inhibit cancer growth.
Flaxseed, the richest source of lignans,
may prevent the spread of cancer.
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Fig. H13-1 (4)Page 468
An Array of Phytochemicals in a Variety of Fruits
and Vegetables (contd)
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 de
fend against cancer.
Blueberries, a rich source of flavonoids,
improve memory in animals.
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In-text Figure Page 469
Functional foods currently on the market promise
to enhance mood, promote relaxation and good k
arma, increase alertness, and
improve memory, among other claims.