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DEMS > Trace Elements > Flashcards

Trace Elements Flashcards

1
Q

Bioavailability

A

the extent to which other dietary constituents affect the absorption and retention of a nutrient

trace mineral are especially susceptible to interference with absorption

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2
Q

Iron - what does it do?

A

Tissue oxygenation

  • O2 transport
  • Electron transport
  • Enzymes for O2 activation

CNS myelination: dopamine synthesis

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3
Q

Iron - where do we get it?

A

Heme - meat/liver
Non-heme - legumes, whole grains, nuts
fortified

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4
Q

Iron absorption form?

A

Heme Fe»Non heme (>30% vs <10%)

Calcium is the only dietary factor that can decrease heme iron absorption!

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5
Q

which dietary factor can decrease heme iron absorption?

A

calcium

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6
Q

Positive factors affecting non-heme iron absorption

A

Vitamin C

Meat/fish

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7
Q

Negative factors affecting non-heme iron absorption

A 
PHYTATES!! (bran / oat / beans / rye)
calcium 
polyphenols
fiber
soy
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8
Q

Phytate (phytic acid)

A

binds zinc / iron / calcium - in gut lumen
humans dont have phytases

high in grains and legumes (maize/wheat>legumes>rice)

major cause of dietary deficiency

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9
Q

Despite the absolute amount of iron in food, the bioavailability markedly influence absorption

A 
meat - high 
kidney bean - low
bread - low
human milk - high
formula - low
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10
Q

What is iron’s main point of regulation?

A 
Amount absorbed 
(mostly proximal duodenum)

deficiency - increased abs
inflammation - decreased abs

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11
Q

What is iron’s main loss?

A

Loss not regulated

Bleeding / cell sloughing

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12
Q

Hepcidin?

A

Blocks transport of iron - binds ferroportin (by regulating ferroportin, hepcidin controls entry of iron into plasma)

  • decreased in iron deficiency
  • increased in inflammation

what is it? antimicrobial peptide synthesized in enterocytes

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13
Q

what form of iron is absorbed?

A

Fe2+

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14
Q

ferritin

A

storage form of iron
liver
bone marrow
spleen

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15
Q

during inflammation, hepcidin increases and iron uptake decreases but what happens to ferritin levels?

A

they may be normal or high - always obtain inflammtory markers with ferritin levels

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16
Q

tranferrin

A

transports in blood

17
Q

iron deficiency -etiology

A 
poor bioavailability dietary iron
dietary inadequacy
high demand - hemolysis / helminths
pregnancy / infancy / growth
chronic immuno-stimulation (increased hepcidin)
18
Q

what is the most common micronutrient deficiency in world and us

A

iron

19
Q

iron deficiency

at risk?

A 
BF infants
Premature
Young children
Adolescent girls
Preg
Blood loss
Obese / sp BS
20
Q

Iron deficiency effects?

A

Anemia (microcytic, hypchromic) - reduced O2 carrying capacity

Impaired cognitive function in Developing brain - irreversible, even w/ correction of deficiency anemia

Iron is prioritized to erythrocytes - so if see anemia likely fucking up earlier cascade

21
Q

Iron deficiency - don’t be fooled

A

Lab values may all be normal in earlier stages when brain stores are depleted an you will only have low ferritin

22
Q

Effect of Iron deficiency in early infancy on cognitive function

A

even in absence of anemia can impair behavioral and cognitive development

23
Q

Iron toxicity

A

Potent pro-oxidant
But normal individuals are able to REGULATE ABSORPTION

Overdose - hemorrhagic gastroenteritis, shock, liver fialure

24
Q

Hereditary hemochromatosis

A

defect in hepcidin

absorption excessive - accumulate iron - liver damage

25
Q

Zinc - what does it do

A

Regulate gene expression
Stabilize molecules
Co-factor for enzymes
Modulates hormone and NT activity

26
Q

nutritional / physiologic role zinc

A

Growth and tissue proliferation

somatic
immune
wound
GI integrity
skin

Antioxidant
Sexual maturation

27
Q

Zinc source

A

animal sources richest

BF only adequate first 6 months of life (regardless of maternal intake)

28
Q

Zn absorption

2 factors

A

amount ingested
dietary phytate

unlike Fe, host dietary status not factor

29
Q

Zinc homeostasis - the role of the GI tract

A

Major site of zinc losses resulting from secretion of endogenous zinc

The amount secreted depends on host status but can also increase in diarrhea and steatorrhea -

Unlike Fe, can excrete Zn

NO stores?

30
Q

Who is at risk for Zn deficiency?

A 
BF infants > 6 mos
young children 
pregant and lactating
elderly 
monotonous plant diet
GI illness / injury - increased losses
woundes / burns - tissue repair
31
Q

Manifestation of Zn deficiency

A 
dermatitis (periacral-periorifical)
personality changes
STUNTING
immune dysfunction 
delayed sex maturation  - HYPOGONADISM
anorexia 
diarrhea
32
Q

Inherited defect in Zn absorption?

A

acrodermatitis enteropathica (AE)

transient neonatal zn deficiency

33
Q

Zn deficiency prevalance

A

second most common globally - second only to iron

34
Q

STUNTING

A

Strongly associated with zinc deficiency

35
Q

Why do we worry about STUNTING in early post-natal life?

A

Linear growth velocity prior to 1 year of age predicts IQ AT 9 YO

36
Q

What impact (3) did Zn supplementation have in young children in developing countries?

A

decreased diarrhea
decreased pneumonia
4th best way to prevent deaths

37
Q

Zn deficiency in US

A

Older infants and toddlers (esp. breastfed >6mo)
- Growth faltering / anorexia

celiac / CF / liver disease

ELDERLY - incrased pneumonia

38
Q

Zn toxicity

A

low compared to iron
decreased Cu absopriton
lowered HDL

DEMS (21 decks)

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