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Trace Elements. Reed A Berger MD Visiting Clinical Professor in Nutrition. Trace Elements. -a naturally occurring, homogeneous, inorganic substance required in humans in amounts less than 100 mg/day. Copper. -found in the liver, brain, heart, kidneys, and muscle

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Trace elements

Trace Elements

Reed A Berger MD

Visiting Clinical Professor in Nutrition


Trace elements1
Trace Elements

  • -a naturally occurring, homogeneous, inorganic substance required in humans in amounts less than 100 mg/day


Copper
Copper

  • -found in the liver, brain, heart, kidneys, and muscle

  • -about 90% of copper in the plasma is in the form of ceruloplasmin

  • -the rest is bound to albumin, transcuprein, and AA’s


Functions
Functions

  • -component of many enzymes

  • -oxidation of Fe prior to transport in the plasma

  • -cross-linking of collagen

  • -mitochondrial energy production, protection from oxidants, etc…


Absorption transport excretion
Absorption, Transport, Excretion

  • -some absorption from the stomach, but most in the small intestine

  • -absorption varies—it decreases with increased intake


Metabolism
Metabolism

  • -for short term transport to the liver copper is carried primarily by albumin

  • -copper-albumin complex acts as a temporary storage site for copper

  • -in the liver, metallothionein is the storage site

  • -ceruloplasmin is the storage site in the plasma and cells


  • -secreted from the liver as a component of bile

  • -once in the GI tract, it becomes part of the body’s pool and is reabsorbed or excreted depending on the body’s need

  • -biliary excretion increases in response to copper overload

  • -small amts of copper are present in the urine, sweat, and menstrual blood

  • -can be conserved by the kidney for reabsorption


  • -unabsorbed copper is in the feces

  • -in high levels, zinc can induce copper deficiency by stimulating intestinal cells to produce more metallothionein which binds copper more avidly than zinc and then is exfoliated with the intestinal cells

  • -fiber and phytate do not adversely effect copper absorption


Rda and sources
RDA and Sources

  • -see handout


Deficiency
Deficiency

  • -decrease in serum copper and ceruloplasmin levels are seen

  • -neutropenia, leukopenia,bone demineralization

  • -subperiosteal hemorrhages, hair and skin depigmentation, defective elastin formation

  • -failure of erythropoiesis, cerebral and cerebellar degeneration>>>death



Menke s disease
Menke’s disease children

  • -sex-linked recessive defect that results in copper malabsorption, increased urinary loss, and abnormal intracellular copper distribution

  • -affected infants: retarded growth, defective keratinization and pigmentation of hair, hypothermia, degenerative changes of the aorta, mental deterioration, abnormalities of the metaphyses of long bones

  • -all of the above is due to interference with collagen and elastin cross-linking


Menke s cont d
Menke’s cont’d children

  • -there is accumulation of copper in the intestinal mucosa even though copper and ceruloplasmin levels are very low

  • -transient improvement with parenteral copper



Toxicity
Toxicity malabsorptive diseases, celiac sprue, tropical sprue, protein-losing enteropathies, and nephrotic syndrome

  • -increased copper levels seen during pregnancy and in women on OCP’s, those with acute and chronic infections, pts with liver disease

  • -***any liver disease that interferes with bile excretion (primary biliary cirrhosis) and mechanical obstruction causes increases in liver copper

  • -***Wilson’s disease: accumulation of excessive copper in the body tissue as the result of a genetic deficiency in the liver synthesis of ceruloplasmin


Iodine
Iodine malabsorptive diseases, celiac sprue, tropical sprue, protein-losing enteropathies, and nephrotic syndrome

  • -body normally has 20-30 mg of iodine and more than 75% is in the thyroid gland

  • -the rest is in the mammary gland, gastric mucosa, and blood

  • -it’s only function is related to thyroid hormone


Absorption and excretion
Absorption and Excretion malabsorptive diseases, celiac sprue, tropical sprue, protein-losing enteropathies, and nephrotic syndrome

  • -iodine is absorbed in the form of iodide

  • -occurs both as free and protein-bound iodine in circulation

  • -iodine is stored in the thyroid where it is used for the synthesis of T3 and T4

  • -the hormone is degraded in target cells and in the liver and the iodine is conserved if needed

  • -excretion is primarily via urine

  • -small amts from bile are excreted in the feces


Deficiency1
Deficiency malabsorptive diseases, celiac sprue, tropical sprue, protein-losing enteropathies, and nephrotic syndrome

  • -goiter—enlargement of the thyroid gland

  • -deficiency may be absolute—in areas of deficiency, or relative—adolescence, pregnancy, lactation

  • -goiters are more prevalent in women and with increased age


  • -goitrogens occurring naturally in foods can cause goiter by blocking absorption or utilization of iodine (cabbage, turnips, peanuts, soybeans)

  • -***severe deficiency during gestation and early postnatal growth: cretinism—mental deficiency, spastic diplegia, quadriplegia, deaf mutism, dysarthria, shuffling gait, short stature, hypothyroidism


Toxicity1
Toxicity blocking absorption or utilization of iodine (cabbage, turnips, peanuts, soybeans)

  • -iodine has wide margin of safety

  • -goiter usually occurs with excess intake>need


Chromium functions
Chromium--Functions blocking absorption or utilization of iodine (cabbage, turnips, peanuts, soybeans)

-required for normal lipid and CHO metabolism and for the fxn of insulin

-?can supplementation raise HDL


Absorption and excretion1
Absorption and Excretion blocking absorption or utilization of iodine (cabbage, turnips, peanuts, soybeans)

  • -10-25% absorption in its trivalent form

  • -amount absorbed remains constant at dietary intakes >40 ug (micrograms) at which point excretion in urine is proportional to intake

  • -increased intake of simple sugar, strenuous exercise, or physical trauma also increase urinary excretion

  • -both chromium and Fe are carried by Tf, however albumin can also assume this role


Deficiency2
Deficiency blocking absorption or utilization of iodine (cabbage, turnips, peanuts, soybeans)

  • -altered CHO metabolism, impaired glucose tolerance, glycosuria, fasting hyperglycemia, increased insulin levels and decreased insulin binding

  • -impaired growth, peripheral neuropathy, negative nitrogen balance

  • -increased chromium losses in stress

  • -hyperglycemia and wt loss reverse with IV supplementation in TPN


Cobalt
Cobalt blocking absorption or utilization of iodine (cabbage, turnips, peanuts, soybeans)

  • -most stored with vitamin B12

  • -component of B12—cobalamin

  • -essential for maturation of RBC’s and normal function of all cells


Absorption and excretion2
Absorption and Excretion blocking absorption or utilization of iodine (cabbage, turnips, peanuts, soybeans)

  • -shared with Fe

  • -absorption is increased in pts with deficient Fe intake, portal cirrhosis with Fe overload, and hemochromatosis

  • -excretion is mainly thru the urine

  • -small amts in feces, hair, sweat


Sources and intakes
Sources and Intakes blocking absorption or utilization of iodine (cabbage, turnips, peanuts, soybeans)

  • -microorganisms are able to synthesize B12

  • -***humans must obtain B12 and cobalt from animal foods such as organ and muscle meat

  • -***takes a long time to become deficient—happens in vegetarians


Deficiency3
Deficiency blocking absorption or utilization of iodine (cabbage, turnips, peanuts, soybeans)

  • -related to vit B12 deficiency

  • -**macrocytic anemia

  • -genetic defect: pernicious anemia

  • -tx: massive doses

  • -more in the vitamin lecture


Toxicity2
Toxicity blocking absorption or utilization of iodine (cabbage, turnips, peanuts, soybeans)

  • -polycythemia

  • -hyperplasia of BM

  • -reticulocytosis

  • -increased blood volume


Selenium
Selenium blocking absorption or utilization of iodine (cabbage, turnips, peanuts, soybeans)

  • -glutathione peroxidase

  • -acts with other antioxidants and free radical scavengers

  • -overlaps with vit E for antioxidant effects

  • -fxn with vit E to protect cell and organelle membranes from oxidative damage


Absorption and excretion3
Absorption and Excretion blocking absorption or utilization of iodine (cabbage, turnips, peanuts, soybeans)

  • -upper segment of the small intestine

  • -increased absorption with deficiency

  • -status is measured by measuring selenium or glutathione peroxidase in plasma, platelets, and RBC’s or selenium levels in whole blood or urine

  • -RBC selenium is an indicator of long-term status


Deficiency4
Deficiency blocking absorption or utilization of iodine (cabbage, turnips, peanuts, soybeans)

  • -rare

  • -Keshan Dz or Kashin-Beck Dz

  • -long term TPN, cancer, CF


Molybendum
Molybendum blocking absorption or utilization of iodine (cabbage, turnips, peanuts, soybeans)

  • -relationship with copper and sulfate

  • -cofactor of many enzymes involved in the catabolism of sulfur AA, purines and pyridines

  • -Toxicity: gout-like syndrome, reproductive SE’s

  • -Deficiency: increased risk with co-existing copper deficiency, TPN


Silicon vanadium arsenic boron
Silicon, Vanadium, Arsenic, Boron blocking absorption or utilization of iodine (cabbage, turnips, peanuts, soybeans)

  • -see handouts

  • -will not be on the exam!!!


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