Micronutrients: Trace Elements Flashcards
what is the definition of trace elements
Minerals for which daily dietary intake is < 100 mg.
what is the function of IRON
Oxygen transport in blood (hemoglobin) and muscle (myoglobin)
Electron transfer enzymes (cytochromes)
Enzymes for activation of oxygen (oxidases and oxygenases)
what are the food sources of Iron
Heme iron: Cellular animal protein: meats, poultry, liver; (milk is poor source)
Non-heme: legumes, nuts, whole grains (esp when enriched/fortified, green leafy vegetables;
How does the chemical form of iron affect Iron absorption?
heme (heme iron enhances absorption of non-heme))
what is the main site of Iron regulation
Main site of regulation is intestinal absorption
what is the major route of iron loss
bleeding
what organs are the main stores of iron in the body
liver, bone marrow, spleen
what is the Transport form of iron called?
Transferrin
what is the storage form of iron called?
ferritin or hemosiderin (aggregated ferritin molecules)
_____ is the Most common nutritional deficiency in the world;
Iron
which populations are at risk for iron deficiency
infants > 6 mo old (low stores, high requirement); premature infants (very low stores, high requirement); adolescents (relatively high requirement + poor intake); pregnant women (increased requirement); populations with chronic infestations (e.g. helminths, causing intestinal blood loss), bariatric surgery patients, hospitalized elderly or elderly in long term care facilities.
what are the signs of Iron deficiency?
Anemia (microcytic, hypochromic), Decreased exercise/work tolerance, fatigue, listlessness.
Deficiency w/o anemia: impaired cognitive function (permanent if onset in infancy?), impaired growth
what is the caveat when checking ferretin for patiens you suspect are iron deficient
ferritin is an acute phase protein, and is elevated with inflammatory conditions; need to check inflammatory marker (ESR or CRP) coincidentally w/ ferritin for accurate interpretation);
Iron is a potent ______
pro-oxidant
Medicinal Fe overdose is esp toxic; the effects are:
Hemorrhagic gastroenteritis, shock & acidosis, coagulation defects, hepatic failure.
In children, 1-2 grams of iron may be fatal.
what are the functions of zinc?
Regulation of gene expression (zinc finger transcription proteins, both RNA & DNA metabolism).
Structural roles in membrane stability
Zinc is Especially critical during periods of _____
growth and cellular/tissue proliferation
what is Acrodermatitis Enteropathica?
Due to mutation in enterocyte Zn transporter (ZIP4); fatal condition if not treated; responds to high doses of Zn supplements (lifetime); presents w/ severe dermatitis, growth failure, diarrhea
what is seen in mild zinc deficeincey
Growth retardation
Anorexia
increased infections
___ blocks transport of Iron
Hepcidin
how does ascorbic acid affect Iron absorption?
ascobic acid affects the oxidation state of iron. it reduces Fe3+ to Fe2+; absorption is enhanced for the reduced state)
what are dietary factors that affect iron absorption
insoluble complexes are formed by phytate, tannins phosphate, and oxalate
what are host factors that affect Iron absorption
Physiologic states (Pregnancy, growth, erythropoiesis); Fe deficiency increases absorption; inflammation: ↑ hepcidin from liver = ↓ absorption at enterocyte
What Mineral-mineral interactions affect Iron absorption
excessive Zn or Cu decrease Fe absorption
How does the Quantity of iron present in the meal/gut lumen affect absorption?
inverse relationship
