Chap12nutri

TRACE MINERALS OTHER THAN FLUORIDES

DBACoojacinto

LianzaMicu

Essential Trace Minerals

Essential Trace Minerals Trace elements or micro-minerals Inorganic nutrients required by humans in

very small amounts from 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

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

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,

F2. Those that are integral constituents or activators of enzymes –

Mn, Mo, Se, Cr, Co

Iron

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 of iron in 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

Physiological Functions

AbsorptionTransport

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 foods more 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.

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

Absorption 2 most important factors determining the

regulation of iron absorption:1. The state of iron stores in the body2. 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

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

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.

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

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 wines4. Failure of the body to regulate absorption, as in

alcoholics on low-protein diets and in patients with hereditary hemochromatosis

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

Food Sources 3 forms of iron in food

1. Heme2. Nonheme3. 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

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

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

Additive iron found in both enriched and fortified products

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

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 Vomiting, diarrhea, and intestinal hypermotility

increases iron loss.

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

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

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.

ZINC

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.

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

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

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.

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.

Deficiencies Causes

Poor diet Excessive alcohol intake Liver disease Chronic kidney disease Genetic disorders

Acrodermatitis enteropathica A sever gastrointestinal and cutaneous disease

May intensify the anemia of sickle-cell disease

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

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)

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

SELENIUM

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.

MOLYBDENUM

Molybdenum Part of the molecular structure of two

enzymes: Xanthine oxidase and Aldehyde oxidase, Xanthine oxidase is responsible for the conversion of xanthine to uric acid.

Daily intake is 0.15 to 0.5mg

CHROMIUM

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

COPPER

Copper

Functions :1. Aids in synthesis of hemoglobin in the bone

marrow2. Form and maintain compounds having

enzymatic activity3. Influence the central nervous system physiology4. Aids in formation of pigments5. 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

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

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.

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

COBALT

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

MANGANESE

Manganese Functions :1. needed for normal bone structure2. For reproduction3. Normal functioning of CNS4. 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

Manganese

Effects of deficiency and excess : 1. Manganese deficiency produces skeletal

abnormalities in animals2. Excesses can produce profound neurological

disturbances similar to those of Parkinson’s disease

Manganese Average adult estimated safe and adequate

daily dietary intake appears to be between 2.5 to 5mg

IODINE

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.

Effects of Imbalance

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

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

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)

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

Effects on development of dental caries

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

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