2. The Trace Minerals
• Needed in much smaller amounts
• Are essential
• Difficult to study due to the trace amounts
needed by the body
• Food content dependent on soil content
• Animal sources of mineral are generally better
absorbed.
4. Iron
• Ferrous (Fe++
)
– Reduced
• Ferric (Fe+++
)
– Oxidized
• Chief functions in the body
– Part of the protein hemoglobin, which carries
oxygen in the blood
– Part of the protein myoglobin in muscles,
which makes oxygen available for muscle
contraction
– Necessary for the utilization of energy as part
of the cells’ metabolic machinery
Copyright 2005 Wadsworth Group, a division of Thomson Learning
5. Iron
• Found in minute amount in every cell
• 15% is absorbed
• Heme iron Vs. Nonheme iron
–40% of iron in animal flesh is heme iron
–Heme iron is better absorbed than
nonheme
• Vitamin C enhances absorption
7. Some iron
delivered to
myoglobin of
muscle cells
Some
losses if
bleeding
occurs
Iron-containing
hemoglobin in
red blood cells
carries oxygen.
Transferrin carries
iron in blood.
Fig. 13-3, p. 445
Some losses
via sweat,
skin, and
urine
Stepped Art
Bone marrow incorporates
iron into hemoglobin of
red blood cells and stores
excess iron in ferritin
(and hemosiderin).
Liver (and spleen)
dismantles red blood cells,
packages iron into
transferrin, and stores
excess iron in ferritin (and
hemosiderin).
8. Iron
Sources – two forms of iron in food
1. Heme iron – meats, poultry,
fish; readily absorbed
2. Nonheme iron – plants foods;
less absorbed
a. Absorption enhanced by
Vitamin C
b. Absorption diminished by
phytates, oxalates, and
tannic acid
9. Iron: Heme vs. Nonheme
Copyright 2005 Wadsworth Group, a division of Thomson Learning
10. Functions of Iron
• Hemoglobin in red blood cells
– Transports oxygen and carbon dioxide
– High turnover, high demand for iron
• Myoglobin in muscle cells
– Binds oxygen
• Electron transport chain
• Enzyme cofactor
• Immune function
• Drug-detoxification pathway
11. Iron
• 2001 RDA
– Men: 8 mg/day
– Women (19-50 years): 18 mg/day
– Women (51+ years): 8 mg/day
• Upper level for adults: 45 mg/day
• Significant sources
– Red meats, fish, poultry, shellfish, eggs
– Legumes, dried fruits
Copyright 2005 Wadsworth Group, a division of Thomson Learning
12.
13. Iron
• Iron deficiency is the most common
nutrient deficiency worldwide
• Can occur if inadequate intake or
blood loss
• Females are prone due to
menstruation, lower iron intake &
pregnancy
• Preschoolers also at risk due to high
milk diets
Copyright 2005 Wadsworth Group, a division of Thomson Learning
14. Iron
• Deficiency symptoms
– Microcytic, hypochromic anemia (low Hgb &
Hct): weakness, fatigue, headaches
– Impaired work performance and cognitive
function
– Impaired immunity
– Pale skin, nailbeds, mucous membranes,
and palm creases
– Concave nails
– Inability to regulate body temperature
– Pica (craving for ice, clay, paste, and other
non-food substances)
Copyright 2005 Wadsworth Group, a division of Thomson Learning
15. • Both size and color
are normal in
these blood cells
• Blood cells in iron-
deficiency anemia
are small and pale
because they
contain less
hemoglobin
16. Iron
• Toxicity – “iron overload”; more common
in men
-Hemochromatosis – genetic defect
-Hemosiderosis – chronic ingestion of too
much iron; more common in alcoholics
-Iron poisoning – acute toxicity from
overdose of iron supplements; can be
deadly in small children
• Toxicity symptoms
– GI distress
– Iron overload: infections, fatigue, joint
pain, skin pigmentation, organ damage
Copyright 2005 Wadsworth Group, a division of Thomson Learning
17. Zinc
• Essential nutrient
• Better absorption from animal
source
• Deficiencies cause growth
retardation and poor sexual
development
18. Zinc
Chief functions in the body
– Part of many enzymes, esp. enzymes
for transfer of carbon dioxide
– Associated with the hormone insulin
– Involved in making genetic material
and proteins
– Important to wound healing, taste
perception, reproduction (the making
of sperm), vision (transports and
activates Vit. A) & immune function
Copyright 2005 Wadsworth Group, a division of Thomson Learning
21. If the body
needs zinc
If the body
does not
need zinc
Mucosal cells in
the intestine
store excess zinc
in
metallothionein.
Zinc is not absorbed
and is excreted in
shed intestinal cells
instead. Thus, zinc
absorption is reduced
when the body does
not need zinc.
Metallothionein
releases zinc to
albumin and transferrin
for transport to the
rest of the body.
Zinc in food
The pancreas
uses zinc to make
digestive enzymes
and secretes them
into the intestine.
Fig. 13-6, p. 453
Stepped Art
22. Zinc
• Deficiency symptoms
– In children, growth retardation and
delayed sexual maturation
– Impaired immune function
– Hair loss
– Eye and skin lesions
– Loss of appetite and abnormal taste
– Depressed immune function and poor
wound healing
- Night blindness
23. Zinc
• Zinc Absorption and Metabolism
– Zinc Transport
• Transported by the protein albumin
• Binds to transferrin
• Excessive iron and copper can lead to a zinc deficiency
and excessive zinc can lead to an iron and copper
deficiency.
24.
25. Zinc
• Toxicity – not likely, unless
supplement abuse
• Toxicity symptoms
–Loss of appetite, impaired
immunity, low HDL, copper and
iron deficiencies
Copyright 2005 Wadsworth Group, a division of Thomson Learning
26. Selenium
• Readily absorbed
• Excreted through the urine and feces
• Co-factor for glutathione peroxidase
• Protects the heart and other cells from
oxidative damage
• Works together with vitamin E
• Cancer prevention
28. Food Sources of Selenium
• Fish, meat (organ meat), egg, milk, shell fish
• Grains, seeds, nuts dependent on soil content
• RDA for adults is 55 ug/day
• Average intake exceeds RDA
29. Toxicity of Selenium
• Upper Level is 400 ug/day
• Garlicky breath
• Hair loss
• Nausea, vomiting
• Weakness
• Rashes
• Cirrhosis of the liver
30. Iodine
• Found in an ion form, iodide
• Used for thyroid hormone synthesis
• Regulates metabolic rate, growth,
development
• Thyroid gland enlarges (goiter) with low
intake of iodide
• Cretinism is the stunting of fetal growth
and mental development as a result of low
iodine diet
31. Iodine
• Chief functions in the body
– A component of two thyroid hormones
that help to regulate growth,
development, and metabolic rate
• 2001 RDA for adults: 150 µg/day
• Upper level: 1100 µg/day
32. Iodine
• Significant sources
–Iodized salt, seafood,
bread, dairy products,
plants grown in iodine-
rich soil and animals
fed those plants
(content of iodine in
soils affects food
content)
Copyright 2005 Wadsworth Group, a division of Thomson Learning
33. Iodine
• Deficiency disease
-Simple goiter-enlarged thyroid; affects
200 million people worldwide
-Creatinism- severe mental and
physical retardation in infants
• Deficiency symptoms
– Underactive thyroid gland, goiter
• Toxicity symptoms
– Underactive thyroid gland, elevated TSH,
goiter (also causes enlarged thyroid gland)
Copyright 2005 Wadsworth Group, a division of Thomson Learning
34.
35. Food Sources of Iodine
• Iodized salt (1/2 tsp. meets RDA for iodine)
• Saltwater fish, seafood, dairy, grains
• Sea salt is a poor source (loss during
processing)
• Plant source dependent on soil content
• RDA for adult is 150 ug/day (50ug to
prevent goiter)
• Average intake exceeds RDA
36. Toxicity of Iodine
• Thyroid hormone synthesis is inhibited
• “Toxic goiter” results
• Consumption of seaweed
• Upper Level is 1.1 mg/day
37. Copper
• Aids in iron metabolism
• Absorption dependent on body’s needs
• Absorption decreased with high intakes
of vitamin C, phytic acid, fiber, zinc, iron,
certain amino acids
38. Functions of Copper
• Increases iron absorption
• Formation of connective tissue
• In superoxide dismutase
• Immune system, blood clot, brain
development, cholesterol
metabolism
39. Deficiency of Copper
• Anemia
• Decrease WBC
• Bone loss
• Inadequate growth
• Pre-term infants at risk
• Cardiovascular disease
40. Food Sources of Copper
• Organ meats
• Seafood
• Cocoa
• Mushroom, legumes, seeds, nuts, whole-grain
• RDA is 900 ug/day for adults
• Daily Value is set at 2000 ug
• Average intake is about or slightly below the RDA
41. Fluoride
• Role in prevention of cavities
• Resists acid and dental caries
• Fluoride inhibits bacterial growth that
may cause cavities
• Fluoridated water (1ppm)
42. “Food” Sources of Fluoride
• Fluoridate water (~0.2 mg/cup)
• Tea
• Seafood, seaweed
• Toothpaste
• Adequate intake is 3.1 -3.8 mg/day for adults
• Typical fluoridated water contains 0.2 mg/cup
43. Toxicity of Fluoride
• Fluorosis
• Mottling of the teeth in children
• Limit toothpaste to pea size for children
• In high amounts can weaken teeth in children
• Upper Level is 10 mg/day
46. Manganese
• Chief functions in the body
– Cofactor for several enzymes
– Component of bones and glands
• 2001 AI
– Men: 2.3 mg/day
– Women: 1.8 mg/day
• Upper level for adults: 11 mg/day
Copyright 2005 Wadsworth Group, a division of Thomson Learning
47. Manganese
• Significant sources
– Nuts, whole grains, leafy vegetables, tea
• Deficiency symptoms
– Rare; requirements are low
• Toxicity symptoms
– Nervous system disorders
– Has occurred in miners inhaling large
quantities of dust causes brain damage
Copyright 2005 Wadsworth Group, a division of Thomson Learning
48. Molybdenum
• High intake will inhibit copper absorption
• Required by several enzymes
• Deficiency rare
– Increased heart and respiration rates
– Night blindness, mental confusion
– Edema, weakness, coma
• RDA is 45 ug/day
• Average intake is 75-110 ug/day
• Toxicity seen in animals
• Upper Level is 2 mg/day
49. Chromium
• Chief functions in the body
– Enhances insulin action
– CHO & lipid metabolism
• 2001 AI
-Men: 35 µg/day
– Women: 25 µg/day
• Significant sources
– Meats (especially liver)
– Whole grains, brewer’s yeast
Copyright 2005 Wadsworth Group, a division of Thomson Learning
50. Chromium
• Deficiency symptoms
– Diabetes-like condition; mimics
symptoms of diabetes, especially
in elderly
• Toxicity symptoms
– None reported
Copyright 2005 Wadsworth Group, a division of Thomson Learning
51. Other Trace Minerals
• Nickel is a cofactor for certain enzymes.
• Silicon is used in bone and collagen formation.
• Vanadium is for growth, development, and normal
reproduction.
• Cobalt is a key component of vitamin B12.
• Boron may be key in brain activities.
• Arsenic is useful in some types of leukemia.
53. Contaminant Minerals
• Contaminate minerals are also called heavy
metals.
• These include mercury, lead, and cadmium.
• These minerals enter the food supply through
soil, water, and air pollution.
• They disrupt body processes and impair
nutrition status.
54. Contaminant Minerals
• Lead toxicity symptoms in children
– Learning disabilities in children
– Low IQ
– Behavior problems
– Slow growth
– Dental caries
– Iron-deficiency anemia
– Sleep disturbances like night walking, restlessness, and
head banging
– Nervous system disorders and seizures
– Slow reaction time and poor coordination
– Impaired hearing
Editor's Notes
Figure 13.3: Animated! Iron Recycled in the Body.
Once iron enters the body, most of it is recycled. Some is lost with body tissues and must be replaced by eating iron-containing food.
Figure 13.6: Animated! Enteropancreatic Circulation of Zinc.
Some zinc from food is absorbed by the small intestine and sent to the pancreas to be incorporated into digestive enzymes that return to the small intestine. This cycle is called the enteropancreatic circulation of zinc.
