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


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


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


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


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)


• 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


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


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


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)


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)


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


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


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


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


Chromium• Deficiency symptoms– Diabetes-like condition; mimics

symptoms of diabetes, especially in elderly

• Toxicity symptoms– None reported


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

trace minerals

Education