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Flashcards in Trace Minerals Deck (51):
1

Iron

two forms: ferrous (reduced/2+) and ferric (oxidized/3+)
RDA = 18 mg/d (F)
27 mg/d (pregnancy)
8 mg/d (M)

2

Iron functions

heme protein/O2 carrier
electron transport cytochromes
activators of molecular oxygen
- monooxygenase (H)
- cytochrome P450 (H)
- peroxidases (H)
- catalases (H)
- hydroxylases (NH)
- lipoxygenases (NH)
DNA synthesis: ribonucleotide reductase (NH)

3

Heme iron

better absorbed than non-heme
10% of daily Fe intake

4

Non-heme iron

plant-derived and in meat
(60% of iron from meat = non-heme))
poorer absorption than heme iron
enhanced absorption with MFP factor, Vit C, citric/lactic acid, fructose

absorption inhibited by phytates, vegetable proteins, calcium, and tannic acid

5

Iron metabolism

stored as ferritin
- short-term = intestinal mucosal cells
- long-term = liver

transported as transferrin (carries 2 atoms, must be oxidized, which requires copper)

6

Iron-nutrient interactions

zinc - Fe may inhibit its absorption d/t shared transport protein
calcium - decr Fe absorption
copper - required to oxidize Fe; Cu deficiency may exacerbate IDA

7

Iron toxicity

iron overload
hemochromatosis
- cirrhosis
- DM
- cardiomyopathy

8

Iron deficiency

storage depletion
early functional iron deficiency
IDA (microcytic/hypochromic):
- ssx = fatigue, weakness, tachycardia, tachypnea
restless leg syndrome
impaired cognitive development in children:
- hypomyelination
- disrupted dopamine metabolism

9

Risks for iron deficiency

children 6 mo - 4 yo
pregnancy
blood loss
celiac dz
vegetarians/vegans
regular intense exercise

10

Iron sources

heme - meat, poultry, fish
non-heme - meat, nuts, seeds, legumes, green leafs
cast iron cookware

11

Copper

2+ = cupric/oxidized
+ = cuprous/reduced

important for redox rxns
incorporated into cuproenzymes

RDA = 900 mcg/day
UL = 10,000 mcg/day (10 mg)

12

Copper functions

iron metabolism: absorption/heme synthesis/ferroxidases
energy production: ETC/cytochrome c oxidase
nervous sys function: DA production/myelin synthesis
collagen synthesis/cross-linking
melanin synthesis: tyrosinase fx
anti-oxidant: SOD

13

Copper:
nutrient interactions

iron - part of Fe transport protein
zinc - competitive inhibition (must add Cu to Zn supplementation)
vitamin c - supplementation may induce deficiency

14

Copper excess

Wilson's dz (AR)
= accumulation of copper in brain and liver

15

Copper deficiency

unresponsive IDA

16

Copper food sources

seafood (esp oysters)
nuts
seeds
legumes
whole grains
liver

17

Zinc

RDA =
8 mg/day (F)
11 mg/day (M)

UL = 40 mg/day

95% = intracellular, mostly in muscle and bones

18

Zinc absorption

inhibited by : phytates, divalent cations (calcium/iron)
enhanced by : protein
absorption rate varies from 5 - 50%

19

Zinc functions

catalytic (>300 metalloenzymes)
structural
regulatory - cell signaling/gene regulation

20

Zinc : enzymatic functions

insulin production
taste perception
vit A metabolism (retinol >>> retinal)
wound healing
spermatogenesis
growth of developing fetus
digestive enzymes (esp brush border)

21

Zinc : structural importance

zinc fingers = protein stabilization of AA sequences high in cys and his
- SOD (requires Zn and Cu)

metallothionein (intracellular transport protein)
- regulates Zn uptake/transport/regulation
- modulates oxidative stress
- regulates gene transcription

22

Zinc : regulatory

Gene repression/activation
- apoptosis
- cytokine gene regulation

Cell signaling pathway regulation
- hormone release
- nerve impulse transmission/gate kinetics
(affects NDMA and GABA)

23

Zinc toxicity

N/V/D
HA
fatigue
impaired copper absorption/deficiency

usu d/t supplementation

24

Zinc deficiency : children

stunted growth/immature sexual development

25

Zinc deficiency : adults

- impaired digestion/absorption
- poor motor/cognitive ability
- impaired vitamin A metabolism (photophobia/night blindness)
- weakened immune system : decr phago/depressed T cell fx/impaired cytokine production
- alopecia
- skin lesions/nail dystrophy
- delayed wound healing

26

Zinc food sources

meat
eggs
seafood - posters, lobster, crab
legumes
nuts
dairy

27

Iodine

necessary for thyroid function

RDA = 150 mcg/day
pregnancy - 220 mcg/day
lactation - 290 mcg/day

UL = 1100 mcg/day

28

Iodine : thyroid

thyroid uptake regulated by TPO
TPO = heme-containing protein
IDA may >>> decr thyroid function
affected by anti-TPO Aby of hashimoto's

29

Iodine excess

goiter

30

Iodine deficiency

goiter
decr thyroid hormone production
cretinism

selenium def may exacerbate iodine def

31

Iodine food sources

seafood
seaweed
iodized salt (0.5 tsp = RDA)
dairy
plants grown in iodine-rich soil (coastal)

32

Goitrogens

spinach
cabbage/broccoli/kale
soybeans
peanuts
peaches
strawberries
>>> bind iodine, making it unavailable for absorption
cooking limits this

33

Selenium

incorporated into proteins (selenoproteins)
- antioxidant systems : GSH peroxidase
- thyroid metabolism : iodothyronine deiodinase
RDA = 55 mcg/day
UL = 400 mcg/day

34

Selenium excess

loss/brittleness of hair and nails
rare

35

Selenium deficiency

may exacerbate iodine def
immune dysfx
Keshan disease - cardiac abN >>> fibrous cardiac muscle

36

Selenium food sources

brazil nuts
meat
seafood
eggs
whole grains
brown rice
mushrooms
produce - soil dependent

37

Manganese

important for function of metalloproteins
- SOD
- xanthine oxidase
- arginase
- glutamine synthase
- prolidase (collagen synthesis)

38

Manganese absorption

9-16% absorbed in SI
most concentrated in mitochondria
25% stored in bone

AI = 2.3 mg/d for M; 1.8 mg/d for F
UL = 11 mg/d

39

Manganese deficiency

maybe CT/bone issues
correlation with seizures and DM II

40

Manganese excess

not from diet, maybe from environment (pesticides)
>>> CNS disturbances and Parkinson-like sxs

41

Manganese food sources

whole grains - oats
legumes
nuts
coffee
tea
spinach
pineapple

42

Chromium

component of holochromodulin
- incr insulin receptor activity

0.5 - 2.5% absorbed from diet
AI = 25 mcg/d (F); 35 mcg/d (M)
UL not established

43

Chromium deficiency

impaired glucose metabolism

44

Chromium excess

teratogenic, genotoxic, carcinogenic
>>> kidney failure (1 mg/d for > 6 weeks)

45

Chromium food sources

broccoli
whole grains
legumes
nuts
meat

46

Molybdenum

important for O2 transport
component of :
- molyboenzymes of N metabolism (nitrate >> ammonium)
- xanthine oxidase
- sulfate oxidase (cys and met metabolism)
AI = 45 mcg/d
UL = 2 mg/ d

47

Molybdenum deficiency

very rare inborn metabolic disorders >>>
- cerebral atrophy
- intractable seizures

48

Molybdenum excess

little evidence of toxicity
potential for seizures, hallucinations, gout-like sxs

49

Molybdenum food sources

legumes - lentils/peas
whole grains
nuts

avg intake = 76 mcg/d (F); 110 mcg/d (M)

50

Fluoride

95% in bones/teeth
prevents dental caries
not considered essential mineral

AI = 4 mg/day
UL = 10 mg/day

51

Fluoride sources

black tea
fruit juice
crab
municipal water