This document discusses several essential trace minerals, including iron, zinc, and selenium. It provides information on their functions, dietary sources, deficiencies, and recommended intake levels. Specifically, it notes that trace minerals play important roles as enzyme cofactors and in various metabolic processes. Good dietary sources include meat, seafood, grains, fruits and vegetables. Deficiencies can result in conditions like anemia and impaired growth. Supplementation may be necessary in some cases to prevent deficiencies.
3. Essential Trace Minerals
Trace elements or micro-minerals
Inorganic nutrients required by humans in very small
amountsfrom micrograms (o.oo1 mg) to no more
than a few mg - less than 100 mg/day
Essential for humans with vital functions to avoid a
deficiency disease.
Mn, Mo, Se, Cr, Co – human enzymatic actions
Fe, I, Zn – recommended daily allowances
Cu, F – estimated safe ranges and adequate intake
4. Trace Elements: Modes of Action
Act as catalysts either as
Metallo-enzymes
the trace element is an integral part of the enzyme molecule
Fe, Zn, Mo
Cu – firmly bound and incorporated in the protein molecule of
the enzyme tyrosinase
Metal-enzymes
the metal ion is loosely associated with the enzymes
Arginase
Functions as constituents and activators of
hormones
Iodine: found in thyroid hormones
Chromium: insulin activator
Cobalt: acts as a structural center of vit.B12
5. Dietary Sources & Classification
Good sources
Meat
Fish
Natural plant foods
Grains
Beans
Fruits
Vegetables
Consumption of processed foods REDUCES the intake of
essential micronutrients, unless these foods are fortified to
conc’ns at least equal to those naturally occurring in the
product.
2 categories:
1. Those that have well-defined human requirements – Fe, Zn, I,
Cu, F
2. Those that are integral constituents or activators of enzymes –
Mn, Mo, Se, Cr, Co
7. Iron
One of the most important minerals in nutrition
Involved in oxygen transport and cellular respiration
(in hemoglobin)
Serves as an oxygen reserve in muscles metabolism
(in myoglobin)
Total quantity ofironin the body averages about 4g,
consisting of two major fractions:
70% essential body iron
hemoglobin, myoglobin, and intracellular enzymes such as
cytochrome
30% mobilizable iron reserves
ferritin&hemosiderin
9. Absorption
Humans have difficulty in efficient iron absorption.
Only 7-10% of iron in cereals and vegetables
10-30% in animal protein and soybeans
Iron is absorbed in the reduced ferrous state
(divalent) in the upper portion of the small intestine
Ascorbic acid, citric acid, and amino acids
convert the less absorbable ferric (trivalent) iron present
in foodsmore phosphoric absorbable ferrous form
If phytates (a salt of phosphoric acid ester) present
in bran or food phosphates are ingested in excess,
the absorption of iron can be impaired.
10. Absorption
The Ferrous iron is initially taken up by the brush border
of the intestinal wall, where it is passed into the intestinal
mucosal cells.
In the mucosal cells, it can be either bound to:
Transferrin
an iron-binding protein for transport of iron in blood
And absorbed into the bloodstream or combined with
another protein:
Apoferritin
This protein complex is known as ferritin (the storage
form of iron), which remains within the cells and is
released as needed.
Control of iron absorption depends on the amount of iron
deposited as ferritin in the mucosal cells
11. Absorption
2 most important factors determining the regulation
of iron absorption:
1. The state of iron stores in the body
2. The state of RBC formation in the bone marrow
Absorption is increased in conditions that
decrease body iron
during growth or pregnancy when new RBCs are being
produced
during anemia resulting from hemorrhage
12. Transport
Transferrin
special carrier protein in the plasma designed for binding
and transporting iron.
attach to the immature RBC and rapidly pass iron to
them.
attaches to the liver cells and more slowly transfers iron to
them
responsible for recycling iron and transporting it to the
bone marrow by production of new RBCs
The normal plasma iron concentration= 100 µg per
100 mL
The total iron-binding capacity (TIBC) of transferrin =
330 µg/per 100 L
13. Transport
A drop in the saturation of transferrin below 10-15%
indicates iron deficiency anemia
After 120 days, RBCs are destroyed by
reticuloendothelial cells (large phagocytic cell) and
the released iron is taken up by the transferrin
molecules.
14. Iron and Storage Overload
Ferritin
storage form of excess iron in the liver cells as when it is
deposited there among all cells of the body
also found in the cells of spleen and bone marrow
Hemosiderin
an insoluble storage form of iron in the body as when the
amount of of iron in the liver, spleen, and bone marrow
EXCEEDS the capacity of the cells to form ferritin.
Hemochromatosis
occurs when there is excessive levels of hemosiderin or iron
overload.
characterized by excess deposition of iron in the tissues,
especially in the liver, and by skin pigmentation
15. Iron and Storage Overload
Common causes of Hemochromatosis:
1. Numerous transfusions in patients with hemolytic
anemia (separation of hemoglobin from red blood cells)
anemias
2. Excessive iron intake from food cooked in iron vessels
3. Drinking excessive amounts of cheap wines
4. Failure of the body to regulate absorption, as in
alcoholics on low-protein diets and in patients with
hereditary hemochromatosis
16. Recommended Dietary Allowances
Iron intake usually tends to be inadequate in the infant
and child during the first 2 years.
The recommended dietary allowance (RDA)=10-15
mg/day
Males
11-18 yrs. old: 18 mg daily
19 and older: 10 mg daily
Females
At childbearing age: 18 mg daily
After menopause: 10 mg
The amount of iron expected from a normal diet is about
6 mg/1000 kcal
Only 10% of iron from is food is absorbed, as this approx.
replaces the 1 mg/day lost physiologically in a normal
adult
17. Food Sources
3 forms of iron in food
1. Heme
2. Nonheme
3. Additive iron
Enriched white bread, rolls, and crackers are a
major source of iron.
The amount of iron to be absorbed from the food
depends or on the bodily need for iron.
The greater the need, the greater the absorption
18. Heme
form of iron in hemoglobin and in myoglobin that is
absorbed intact
found in organ meats (liver, heart, kidney, spleen),
red meats, veal, pork, poultry, fish, oysters, and
clams, but not milk or milk products
About 40% of iron in meat and fish is heme iron
although only 1/3 can be absorbed by the body
19. Nonheme
Accounts for the other 60% of iron in animal protein
and all the iron in molasses, fruits (figs, dates), green
veggies, dried beans, nuts, and grain products
(wheat germ)
Only 2-10% can be absorbed by the body
20. Additive iron
found in both enriched and fortified products
21. Iron Deficiency Anemia
Occurs due to inadequate intake or excessive loss of
iron or both.
Characterized by the production of small RBCs that
are deficient in hemoglobin.
The most common type of nutritional anemia
It leads to loss of efficiency and impaired general
health
22. Occurrences and Causes
Occurs most frequently in infants and children due to
undergoing rapid growth and having rapid RBC
formation
Occurs in pregnant women due to the increasing
demand of the growing fetus on the mother’s body
iron
In adult males and postmenopausal women –
pathological blood loss
In premenopausal women – menstruational blood
loss
Bizarre food habits (avoidance of meat and
vegetables)
Inadequate intake among the elderly due to poverty
23. Clinical Manifestations
Slow development; takes for months or years
Anemia
Characterized by weakness, fatigue, pallor, and
numbness and tingling of the extremities
Epithelial changes – early manifestations
Nail changes; dullness, brittleness
Fingernails may be flat instead of convex; spoon-shaped
appearance with longitudinal ridges (koilonychia)
Hair growth may be altered
Dysphagia (difficulty in swallowing) in severe cases
24. Clinical manifestations: oral area
Glossitis
Inflammation of the tongue
Fissures (clefts or grooves) at the corners of the mouth
The papillae of tongue are atrophied, giving a smooth,
shiny, red appearance to the tongue
The clinical appearance of the tongue in iron deficiency
resembles that in vit.B complex deficiency
Oral mucous membranes may be atrophied and ashen
gray
More susceptible to carcinoma (cancer arising from
epithelial cells)
Plummer-Vinson syndrome
Combination of dysphagia, koilonychia, angular
stomatitis, and atrophic glossitis
25. THERAPY
Administration of 200 mg of ferrous sulfate tablets 3x
a day (after each meal) as prescribed by a physician
Treatment should be continued for approximately 2
months after the hemoglobin level has returned to
normal.
27. Zinc
Approx. 2-3 g of zinc in human body
Is concentrated in the eyes, liver, bones, prostate,
prostatic secretions, and hair
In blood, 85% in RBCs, but each WBC has about
25x than each RBC.
28. Functions
An integral part of at least 70 enzymes that belong to
metallo-enzymes
Active component of carbonic anhydrase
Essential for the transport of CO2 to the lungs
Other enzymes with zinc content
Alcohol dehydrogenase
Lactate dehydrogenase
Activates enzymes (carboxypeptidase and
aminopeptidase) that function in the digestion of proteins
Is part of alkaline phosphatase − bone metabolism
Added to insulin to prolong the hypoglycemic effect
It plays an essential role in RNA, DNA, and protein
synthesis
29. Functions
Essential for wound healing, tissue growth, and
prevention of dwarfism, production of hormones.
Zinc inadequacy may play an important role in
the reduced immune response in protein-calorie
malnutrition
Used in the treatment of sickle-cell disease
Assist in restoring a missing sense of taste in
some cases
Important for thymic hormone activity since its
removal reduces hormone functions
30. Recommended Dietary Allowance
RDI: 15 mg a day
During pregnancy and lactation: 20-25 mg/day
Infant at 6 mos. old: 3 mg/day
6 mos.-1 yr.: 5 mg/day
1-10 yrs.: 10 mg/day
*These are relatively high values when considered in
proportion to the amount of food eaten.
31. Food Sources
Protein rich foods such as meat and fish
Oysters and herring as highest zinc content per
ounce
Milk --- total dietary zinc intake
**Grains contain dietary fiber and phytic acid, that
can bind zinc, inhibiting its absorption, but when
used in making bread with yeast, it inactivates
the phytates and the body now obtains more of
the zinc.
32. Deficiencies
Causes
Poor diet
Excessive alcohol intake
Liver disease
Chronic kidney disease
Genetic disorders
Acrodermatitisenteropathica
A sever gastrointestinal and cutaneous disease
May intensify the anemia of sickle-cell disease
33. Deficiencies
Clinical Manifestations
Retardation of both growth and sexual development
Poor appetite
Slow healing of wounds
Loss of sense of taste
Progressive pustular dermatitis of the extremities, mouth, anus,
and genital areas
Emotional irritability
Tremors
Loss of coordination
In pregnancy
Abnormal taste sensations
Prolonged gestation
Protracted labor
Increased risks to the fetus
34. Supplementation
Consuming excessive amounts of zinc may increase
the risk of cardiovascular disease due to:
Low HDL
High LDL
Common zinc level in popular vitamin/mineral
preparations is 15 mg (safe)
35. Clinical Application
Zinc sulfate supplements can decrease wound
healing time significantly
Zinc peroxide powder when used topically on acute
gingival lesions in acute necrotizing gingivitis, the
soreness disappears soon enough and the mouth
restores to its normal healthy condition
37. Selenium
Essential component of the enzyme that catalyzes
oxidation of glutathione which protects red blood
cells through destruction of hydrogen peroxide
protecting hemoglobin from oxidative damage
Extremely effective in reducing the prevalence of
keshan disease, which is characterized by
abnormalities in the heart muscle.
Estimated safe and recommended daily intake of
selenium for adults is 0.05 to 0.2mg while for
infants, children and adolescents is somewhat less.
39. Molybdenum
Part of the molecular structure of two enzymes:
Xanthineoxidase and Aldehydeoxidase,
Xanthineoxidase is responsible for the conversion of
xanthine to uric acid.
Daily intake is 0.15 to 0.5mg
41. Chromium
Trivalent chromium is the biologically active form of
chromium
Required for the maintenance of normal glucose and
energy metabolism
May act as cofactor in insulin and stimulates
synthesis of fatty acids and cholesterol in the liver
Daily intake is 0.05 to 0.2mg
43. Copper
Functions :
1. Aids in synthesis of hemoglobin in the bone
marrow
2. Form and maintain compounds having enzymatic
activity
3. Influence the central nervous system physiology
4. Aids in formation of pigments
5. Component of enzyme necessary for the oxidation
of the amino acid tyrosine and vitamin C
6. May also have a role in the maintenance of the
myelin sheath around the nerve tissue
44. Copper
Deficiency :
1. Copper deficiency seen in australian lambs called
“swayback disease” characterized by
demyelination and degeneration of motor nerves in
CNS, its prevented by giving copper supplements
to ewes(female sheep) during pregnancy.
2. Found by clinicians that combined administration of
copper and iron is more effective in treating
hypochromic anemia than the administration of iron
alone
45. Copper
Effects of excess :
Accumulation of excess copper in body tissues, probably
because of genetic absence of liver enzyme is called
Wilson’s disease, characterized by neurological
degeneration and cirrhotic liver changes.
Reduction of dietary copper may be useful in treating this
disease.
Also be arrested by giving chelating agents like
penicillamine to mobilize copper from tissues and promote
excretion in the urine.
46. Copper
Excess copper concentrations found in human saliva
appear to inhibit acid production, although there is
nothing conclusive to this theory.
Daily intake is 2 to 3mg
48. Cobalt
Part of the vitamin B₁₂ molecule
May also be involved in the metabolism of sulfur
containing amino acids
Inadequacies of cobalt will cause anemia
Essential for adequate nutrition of sheep and cattle,
deficiency will cause extreme emaciation and
wasting.
High dose of cobalt stimulates the bone marrow to
produce excessive numbers of red
cells(polycythemia) and higher than normal
hemoglobin level
50. Manganese
Functions :
1. needed for normal bone structure
2. For reproduction
3. Normal functioning of CNS
4. Important catalyst and component of many
enzymes in body, Enzymes involved in the
synthesis of carbohydrates, those necessary for
the protection of cells from high levels of oxygen
and enzymes necessary for mucopolysaccharide
synthesis
51. Manganese
Effects of deficiency and excess :
1. Manganese deficiency produces skeletal
abnormalities in animals
2. Excesses can produce profound neurological
disturbances similar to those of Parkinson’s
disease
52. Manganese
Average adult estimated safe and adequate daily
dietary intake appears to be between 2.5 to 5mg
54. Iodine
One of the first trace elements recognized essential
for normal health
Integral part of the hormones thyroxine and
triiodothyronine, functions to maintain the control of
the energy metabolism of the body.
Most important in synthesis of thyroid hormone is
the ability of the thyroid gland to trap and oxidize
iodine molecules into free iodine.
56. Hypothyroidism
Goiter, Thyroid gland enlargement
Develops swelling in the front of neck in the area of
hyoid bone
Iodine deficiency
Potassium iodide in small doses may completely
eliminate goiter
Current level of enrichment furnishes 76 mg of iodine
per g of salt
57. Hypothyroidism
Cretinism and Myxedema are pathological conditions
resulting from low thyroid activity
Treatment is administration of thyroid hormone until
euthyroid(normal) state is achieved
If it affects a fetus prior to birth, cretinism develops
58. Hyperthyroidism
Excessive activity of thyroid gland brought by
deficiency of iodine producing an enlarged excretory
gland as a result of hyperplasia of the cells lining the
follicles along with increased colloidal material
Produces hypermetabolic rate(increase pulse rate,
temperature and blood pressure, extreme
nervousness, irritability, increased sweating,
dyspnea, weight loss and tiredness)
Patients with diffuse primary thyroid hyperplasia may
develop exopthalmos(abnormal protrusion of the
eyeball)
59. Oral Effects of Imbalance
In severe hypothyroidism, jaws are small and rate of
tooth eruption is retarded
Hyperthyroid patients conceivably develop caries
rapidly due to their increased need for calories and
possible use of excessive sugars
61. Mineral Elements That May Inhibit
or Promote Caries
5 Categories of Elements accdg. to their Cariogenicity
(by Navia)
1. Caries-promoting: Selenium, Magnesium,
Cadmium, Platinum, Lead, Silicon
2. Mildly cariostatic: Molybdenum, Strontium, Calcium,
Boron, Lithium, Gold
3. With doubtful effect on caries: Beryllium, Cobalt,
Manganese, Tin, Zinc, Bromine, Iodine
4. Caries-inert: Barium, Aluminum, Nickel, Iron,
Palladium, Titanium
5. Strongly cariostatic: Fluorine, Phosphorus
62. Possible Mechanism of Trace
Elements Action on Dental Caries
By altering the resistance of the tooth by
modifying the local environment at the plaque-
tooth enamel interface
By altering the size of enamel crystals available
to acid exposure; influencing enamel solubility
Smaller crystals have a greater surface area
(more exposed to acid solubility) than larger
crystals in enamel rods of similar size
By influencing the microbial ecology of plaque to
either inhibit or promote the growth of caries-
producing bacteria