Micronutrients: Trace Elements

Question 1

what is the definition of trace elements

Answer 1

Minerals for which daily dietary intake is < 100 mg.

Question 2

what is the function of IRON

Answer 2

Oxygen transport in blood (hemoglobin) and muscle (myoglobin)
Electron transfer enzymes (cytochromes)
Enzymes for activation of oxygen (oxidases and oxygenases)

Question 3

what are the food sources of Iron

Answer 3

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;

Question 4

How does the chemical form of iron affect Iron absorption?

Answer 4

heme (heme iron enhances absorption of non-heme))

Question 5

what is the main site of Iron regulation

Answer 5

Main site of regulation is intestinal absorption

Question 6

what is the major route of iron loss

Answer 6

bleeding

Question 7

what organs are the main stores of iron in the body

Answer 7

liver, bone marrow, spleen

Question 8

what is the Transport form of iron called?

Answer 8

Transferrin

Question 9

what is the storage form of iron called?

Answer 9

ferritin or hemosiderin (aggregated ferritin molecules)

Question 10

_____ is the Most common nutritional deficiency in the world;

Answer 10

Iron

Question 11

which populations are at risk for iron deficiency

Answer 11

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.

Question 12

what are the signs of Iron deficiency?

Answer 12

Anemia (microcytic, hypochromic), Decreased exercise/work tolerance, fatigue, listlessness.
Deficiency w/o anemia: impaired cognitive function (permanent if onset in infancy?), impaired growth

Question 13

what is the caveat when checking ferretin for patiens you suspect are iron deficient

Answer 13

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);

Question 14

Iron is a potent ______

Answer 14

pro-oxidant

Question 15

Medicinal Fe overdose is esp toxic; the effects are:

Answer 15

Hemorrhagic gastroenteritis, shock & acidosis, coagulation defects, hepatic failure.
In children, 1-2 grams of iron may be fatal.

Question 16

what are the functions of zinc?

Answer 16

Regulation of gene expression (zinc finger transcription proteins, both RNA & DNA metabolism).
Structural roles in membrane stability

Question 17

Zinc is Especially critical during periods of _____

Answer 17

growth and cellular/tissue proliferation

Question 18

what is Acrodermatitis Enteropathica?

Answer 18

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

Question 19

what is seen in mild zinc deficeincey

Answer 19

Growth retardation
Anorexia
increased infections

Question 20

___ blocks transport of Iron

Answer 20

Hepcidin

Question 21

how does ascorbic acid affect Iron absorption?

Answer 21

ascobic acid affects the oxidation state of iron. it reduces Fe3+ to Fe2+; absorption is enhanced for the reduced state)

Question 22

what are dietary factors that affect iron absorption

Answer 22

insoluble complexes are formed by phytate, tannins phosphate, and oxalate

Question 23

what are host factors that affect Iron absorption

Answer 23

Physiologic states (Pregnancy, growth, erythropoiesis); Fe deficiency increases absorption; 
inflammation: ↑ hepcidin from liver = ↓ absorption at enterocyte

Question 24

What Mineral-mineral interactions affect Iron absorption

Answer 24

excessive Zn or Cu decrease Fe absorption

Question 25

How does the Quantity of iron present in the meal/gut lumen affect absorption?

Answer 25

inverse relationship