Transcript Trace Minerals

Trace Minerals
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.
Trace Minerals
Iron
Iodine
Fluoride
Manganese
Molybdenum
Nickel
Boron
Zinc
Selenium
Copper
Chromium
Arsenic
Silicon
Cobalt
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
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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
Iron Absorption
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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.
Stepped Art
Fig. 13-3, p. 445
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
Iron: Heme vs. Nonheme
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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
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Electron transport chain
Enzyme cofactor
Immune function
Drug-detoxification pathway
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
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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
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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)
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• Both size and color
are normal in
these blood cells
• Blood cells in irondeficiency anemia
are small and pale
because they
contain less
hemoglobin
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
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Zinc
• Essential nutrient
• Better absorption from animal
source
• Deficiencies cause growth
retardation and poor sexual
development
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
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Zinc
• 2001 RDA
– Men: 11 mg/day
– Women: 8 mg/day
• Upper level for adults: 40 mg/day
• Significant sources
– Protein-containing foods
– Red meats, shellfish
– Whole grains
Copyright 2005 Wadsworth Group, a division of Thomson Learning
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
needs zinc
If the body
Zinc is not absorbed
does not
and is excreted in shed
need zinc
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.
Stepped Art
Fig. 13-6, p. 453
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
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.
Zinc
• Toxicity – not likely, unless
supplement abuse
• Toxicity symptoms
– Loss of appetite, impaired
immunity, low HDL, copper and
iron deficiencies
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Selenium
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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
Deficiency of Selenium
• Muscle pain
• Muscle wasting
• Cardiomyopathy
Food Sources of Selenium
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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
Toxicity of Selenium
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Upper Level is 400 ug/day
Garlicky breath
Hair loss
Nausea, vomiting
Weakness
Rashes
Cirrhosis of the liver
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
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 g/day
• Upper level: 1100 g/day
Iodine
• Significant sources
– Iodized salt, seafood,
bread, dairy products,
plants grown in iodinerich soil and animals
fed those plants
(content of iodine in
soils affects food
content)
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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)
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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
Toxicity of Iodine
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Thyroid hormone synthesis is inhibited
“Toxic goiter” results
Consumption of seaweed
Upper Level is 1.1 mg/day
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
Functions of Copper
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Increases iron absorption
Formation of connective tissue
In superoxide dismutase
Immune system, blood clot, brain
development, cholesterol
metabolism
Deficiency of Copper
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Anemia
Decrease WBC
Bone loss
Inadequate growth
Pre-term infants at risk
Cardiovascular disease
Food Sources of Copper
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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
Fluoride
• Role in prevention of cavities
• Resists acid and dental caries
• Fluoride inhibits bacterial growth that
may cause cavities
• Fluoridated water (1ppm)
“Food” Sources of Fluoride
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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
Toxicity of Fluoride
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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
U.S.
Population
With
Fluoridated
Water
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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
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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
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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
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RDA is 45 ug/day
Average intake is 75-110 ug/day
Toxicity seen in animals
Upper Level is 2 mg/day
Chromium
• Chief functions in the body
– Enhances insulin action
– CHO & lipid metabolism
• 2001 AI
-Men: 35 g/day
– Women: 25 g/day
• Significant sources
– Meats (especially liver)
– Whole grains, brewer’s yeast
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Chromium
• Deficiency symptoms
– Diabetes-like condition; mimics
symptoms of diabetes, especially
in elderly
• Toxicity symptoms
– None reported
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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.
Mineral Pyramid
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.
Contaminant Minerals
• Lead toxicity symptoms in children
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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