stored as ferritin - short-term = intestinal mucosal cells - long-term = liver transported as transferrin (carries 2 atoms, must be oxidized, which requires copper)

Trace Minerals Flashcards by e steele

Iron

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

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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)

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Heme iron

better absorbed than non-heme

10% of daily Fe intake

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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

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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)

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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

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Iron toxicity

iron overload
hemochromatosis
- cirrhosis
- DM
- cardiomyopathy

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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

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Risks for iron deficiency

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

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Iron sources

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

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Copper

2+ = cupric/oxidized
\+ = cuprous/reduced

important for redox rxns
incorporated into cuproenzymes

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

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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

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Copper:

nutrient interactions

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

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Copper excess

Wilson’s dz (AR)

= accumulation of copper in brain and liver

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Copper deficiency

unresponsive IDA

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Copper food sources

seafood (esp oysters)
nuts
seeds
legumes
whole grains
liver

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Zinc

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

UL = 40 mg/day

95% = intracellular, mostly in muscle and bones

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Zinc absorption

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

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Zinc functions

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

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Zinc : enzymatic functions

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

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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

Zinc : regulatory

Gene repression/activation

apoptosis
cytokine gene regulation

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

Zinc toxicity

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

usu d/t supplementation

Zinc deficiency : children

stunted growth/immature sexual development

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

Zinc food sources

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

Iodine

necessary for thyroid function RDA = 150 mcg/day pregnancy - 220 mcg/day lactation - 290 mcg/day UL = 1100 mcg/day

Iodine : thyroid

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

Iodine excess

goiter

Iodine deficiency

goiter decr thyroid hormone production cretinism selenium def may exacerbate iodine def

Iodine food sources

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

Goitrogens

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

Selenium

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

Selenium excess

loss/brittleness of hair and nails | rare

Selenium deficiency

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

Selenium food sources

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

Manganese

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

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 ```

Manganese deficiency

maybe CT/bone issues | correlation with seizures and DM II

Manganese excess

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

Manganese food sources

``` whole grains - oats legumes nuts coffee tea spinach pineapple ```

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

Chromium deficiency

impaired glucose metabolism

Chromium excess

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

Chromium food sources

``` broccoli whole grains legumes nuts meat ```

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

Molybdenum deficiency

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

Molybdenum excess

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

Molybdenum food sources

legumes - lentils/peas whole grains nuts avg intake = 76 mcg/d (F); 110 mcg/d (M)

Fluoride

95% in bones/teeth prevents dental caries not considered essential mineral ``` AI = 4 mg/day UL = 10 mg/day ```

Fluoride sources

black tea fruit juice crab municipal water

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Trace Minerals Flashcards

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