Trace minerals
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Transcript of 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 MineralsIron ZincIodine SeleniumFluoride CopperManganese ChromiumMolybdenum ArsenicNickel SiliconBoron 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
Copyright 2005 Wadsworth Group, a division of Thomson Learning
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
Copyright 2005 Wadsworth Group, a division of Thomson Learning
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).
IronSources – 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
Copyright 2005 Wadsworth Group, a division of Thomson Learning
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
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
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
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
• 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
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 damageCopyright 2005 Wadsworth Group, a division of Thomson Learning
Zinc
• Essential nutrient• Better absorption from animal
source• Deficiencies cause growth
retardation and poor sexual development
ZincChief 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
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
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. 453Stepped Art
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
Copyright 2005 Wadsworth Group, a division of Thomson Learning
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
Deficiency of Selenium
• Muscle pain• Muscle wasting• Cardiomyopathy
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
Toxicity of Selenium
• 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 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
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
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
• 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
• Increases iron absorption• Formation of connective tissue• In superoxide dismutase• Immune system, blood clot, brain
development, cholesterol metabolism
Deficiency of Copper
• Anemia• Decrease WBC• Bone loss• Inadequate growth• Pre-term infants at risk• Cardiovascular disease
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
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
• 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
• 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
Copyright 2005 Wadsworth Group, a division of Thomson Learning
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
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
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
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
Copyright 2005 Wadsworth Group, a division of Thomson Learning
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
– 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