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NUTR2101 > Module 3 wk 12 > Flashcards

Module 3 wk 12 Flashcards

1
Q

explain where iron is found in food , and in what form

A

heme iron (ferrous iron): Fe2+, found in hemoglobin and myoglobin of food products from animal source

non-heme iron (ferric iron): Fe3+, found in plant and grain food products (and minor amounts in meat)

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2
Q

why is iron in plant products less bioavailable?

A

must be converted from 3+ to 2+ valence for absorption
and
plant products also contain factors interfering with iron absorption, even in iron-fortified foods, phytic acid, oxalic acid, polyphenols, fibre

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3
Q

explain how goitre develops in iodine deficiency

A

T4 and T3 level drop -> TSH secretion increases, thyroid gland enlarges to trap more iodine. Low T3 -> symptoms of hypothyroidism

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4
Q

What are the dietary recommendations you give to a vegan consumer about trace minerals (keyword: dietary)

A

Iron
Sources: Lentils, chickpeas, beans, tofu, fortified cereals, spinach, quinoa, and pumpkin seeds.
Enhancement Tips:
Vitamin C: Consume vitamin C-rich foods (citrus fruits, bell peppers, tomatoes) with iron-rich meals to enhance non-heme iron absorption.
Avoid Inhibitors: Limit intake of calcium-rich foods, tea, coffee, and high-phytate foods around meals high in iron to prevent absorption inhibition.

Zinc
Sources: Whole grains, legumes, tofu, tempeh, nuts (cashews, almonds), seeds (pumpkin, sunflower), and fortified cereals.
Enhancement Tips:
Soaking and Sprouting: Soak or sprout legumes, grains, and seeds to reduce phytate levels and enhance zinc absorption.
Fermentation: Include fermented foods (miso, tempeh) which can improve zinc bioavailability.

Selenium
Sources: Brazil nuts (a single nut can meet daily requirements), sunflower seeds, brown rice, whole wheat bread, and mushrooms.
Moderation: Be cautious with Brazil nuts to avoid excessive selenium intake; one to two nuts per day is typically sufficient.

Copper
Sources: Whole grains, nuts (cashews, almonds), seeds (sesame, sunflower), legumes, dark chocolate, and mushrooms.
Balance with Zinc: Ensure a balanced intake of zinc and copper, as high zinc levels can interfere with copper absorption.

Manganese is generally sufficient in a varied vegan diet.

A varied vegan diet typically provides adequate molybdenum.

Chromium is usually adequate in a balanced diet focused on whole, unprocessed foods.

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5
Q

list the minerals studied that are involved in good bone health, and their respective roles

A
  1. Calcium
    Calcium is the primary mineral in bones, giving them strength and structure. It forms hydroxyapatite crystals that provide rigidity to the bone matrix.
    Bone Remodeling: Calcium is essential for the constant process of bone remodeling, involving resorption by osteoclasts and formation by osteoblasts.
  2. Phosphorus
    Bone Formation: Phosphorus is a key component of hydroxyapatite, the mineral complex that makes up bone and tooth enamel.
    Bone Strength: It works with calcium to strengthen bones and teeth.
  3. Magnesium
    Bone Matrix Development: Magnesium is involved in the structural development of bone, with about 60% of the body’s magnesium stored in the bones.
    Calcium Metabolism: It plays a role in regulating calcium levels, ensuring proper mineralization of bones.
  4. Fluoride
    Bone Mineralization: Fluoride helps in the mineralization of bones and teeth by forming fluorapatite, which is more resistant to demineralization than hydroxyapatite.

Dental Health: Fluoride is crucial in preventing dental caries by enhancing the strength and resilience of tooth enamel.

  1. Potassium
    Acid-Base Balance: Potassium helps to neutralize acids in the body, which can otherwise lead to bone demineralization. It helps maintain a proper acid-base balance, protecting bone density.

Bone Preservation: Adequate potassium intake is associated with reduced calcium loss from bones and improved bone health.

  1. Zinc
    Bone Growth and Development: Zinc is essential for bone growth and development. It is involved in the synthesis of collagen and the formation of the bone matrix.
    Enzyme Function: Zinc is a cofactor for enzymes that play a role in bone mineralization.
  2. Manganese
    Bone Formation: Manganese is necessary for the formation of bone cartilage and bone collagen. It acts as a cofactor for enzymes involved in bone formation and metabolism.
    Bone Density: It supports the structural integrity and density of bones.
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6
Q

describe the concept of the mucosal block in the context of trace minerals

A

The mucosal block is a crucial mechanism that helps maintain mineral balance by regulating the absorption of trace minerals at the intestinal level. This process involves the coordination of transport proteins, storage proteins, and regulatory hormones to ensure that the body absorbs only what it needs and prevents toxicity from excessive mineral intake.

iron: ferritin prevent excess absorption

zinc: metallothionein = a binding protein that blocks Zn’s excess movement into circulation. The ‘mucosal block’ is overridden with high doses of supplements.

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7
Q

What mineral is part of the mandatory fortification program in Australia? explain why?

A

mandatory salt iodisation

Thyroid Function: Iodine is an essential mineral required for the synthesis of thyroid hormones, which are crucial for regulating metabolism, growth, and development.
Preventing Iodine Deficiency Disorders: Adequate iodine intake is vital for preventing iodine deficiency disorders (IDDs), which include goiter (enlarged thyroid gland), hypothyroidism, and various developmental abnormalities in children, such as cretinism.

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8
Q

What are the trace minerals at risk in the context of chronic alcohol consumption? explain why and the consequences overtime.

A

Zn: functions in alcohol dehydrogenase, converts ethanol to acetaldehyde
will result in reduced HCl production and can lead to anorexia (loss of appetite)

increases renal excretions of manganese, iron, magnesium, selenium, copper

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9
Q

explain why selenium deficiency can result in iodine function deficiency

A

has a coenzyme cofactor role in iodothyronine 5’ deiodinases: three forms of enzyme, active in different sites, convert T4 to T3 by removing 1 Iodine

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10
Q

Type of iron found exclusively in animal products

A

heme iron

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11
Q

Type of iron found in both plant and animal products

A

Non-heme iron

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12
Q

Ferric iron is reduced to ferrous iron by HCl, ascorbic acid and _______ in the duodenal brush border

A

reductases

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13
Q

Ferrous iron is absorbed via

A

DMT1

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14
Q

DMT1 synthesis is influenced by _______

A

iron status

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15
Q

Heme iron is absorbed via

A

HCP1

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16
Q

Fe2+ is stored in enterocytes bound to _______

A

ferritin

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17
Q

Ferrous iron is transported across the basolateral membrane of enterocytes via _______

A

ferroportin

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18
Q

Membrane-bound copper-dependent enzyme that oxidises Fe2+ to Fe3+ for transport

A

hephaestin

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19
Q

Copper-dependent enzyme that oxidises Fe2+ to Fe3+ in the circulation

A

ceruloplasmin

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20
Q

Fe3+ is transported in the blood bound to _______

A

transferrin

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21
Q

Iron is taken up into body cells via _______

A

endocytosis

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22
Q

Heme-containing protein that transports oxygen in red blood cells

A

hemoglobin

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23
Q

Heme-containing protein that stores oxygen in muscle cells

A

myoglobin

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24
Q

Iron is a cofactor in lysyl and prolyl hydroxylase involved in _______ synthesis

A

collagen

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25
Q

Iron-dependent antioxidant enzyme that converts hydrogen peroxide to water and oxygen

A

catalase

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26
Q

Iron-dependent enzyme involved in the synthesis of thyroid hormones

A

Thyroid-peroxidase

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27
Q

Iron is a cofactor to phosphoenolpyruvate carboxykinase which is required for _______

A

gluconeogenesis

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28
Q

Iron-deficiency results in what kind of anaemia?

A

Microcytic hypochromic

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29
Q

Iron toxicity can result from a genetic disorder called _______ where regulation of intestinal iron absorption is impaired

A

Hemochromatosis

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30
Q

Factors increasing iron absorption

A

heme-iron
vitamin C
high demands for red blood cells
meat protein factor (MPF)
gastric acidity
low iron stores

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31
Q

Factors decreasing iron absorption

A

high iron stores
excessive intake of other minerals
polyphenols
antacids
phytic acid
oxalic acid

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32
Q

Zinc deficiency was first identified in high phytate diets in the Middle East, resulting in _______

A

Adolescent nutritional dwarfism

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33
Q

Major zinc transporter for absorption into enterocytes

A

ZIP4

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34
Q

In large doses (e.g. supplements) zinc is absorbed via _______

A

Paracellular diffusion

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35
Q

Protein that binds and stores zinc in enterocytes and body tissues

A

Metallothionein

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36
Q

Zinc is transported across the basolateral membrane of enterocytes via _______

A

ZnT1

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37
Q

Zinc is transported in the circulation bound to _______, α2-macroglobulin, or histidine or methionine

A

albumin

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38
Q

Zinc is needed for the conversion of retinol to retinal as a cofactor of _______

A

Alcohol dehydrogenase

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39
Q

Carboxypeptidases A and B are zinc-dependent enzymes involved in _______

A

protein digestion

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40
Q

Polyglutamate conjugase is a zinc-dependent enzyme involved in _______

A

Folate digestion

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41
Q

Zinc plays a _______ role in the antioxidant enzymes SOD1 and SOD3

A

Structural

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42
Q

Zinc deficiency leads to poor wound healing due to the role of zinc in _______

A

Matrix-metalloproteinases

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43
Q

Zinc fingers promote the binding of _______ to MREs in the promoter region of genes

A

Transcription factors

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44
Q

Zinc deficiency reduces the _______ response to carbohydrates

A

Insulin

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45
Q

Zinc deficiency results in reduced taste acuity due to its role in _______

A
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46
Q

An especially good source of zinc

A

oysters

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47
Q

Copper is found in food primarily in the ____ valence

A

2+

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48
Q

Copper is absorbed in the ____ valence

A

1+

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49
Q

Cupric copper is reduced to cuprous copper by HCl, _______ and reductases in the duodenal brush border

A

Vitamin C

50
Q

Copper is mainly absorbed in the duodenum but some is absorbed in the _______

A

stomach

51
Q

Citric, malic, gluconic and acetic acid _______ copper for absorption

A

chelate

52
Q

Copper is stored in enterocytes bound to _______

A

Metallothionein

53
Q

Copper is transported to the liver bound to _______ and α2-macroglobulin

A

albumin

54
Q

Copper is released from the liver and transported in the circulation bound to _______

A

Ceruloplasmin

55
Q

Copper is a cofactor in dopamine monooxygenase for the synthesis of _______

A

Norepinephrine

56
Q

Copper is a cofactor of the antioxidant enzyme _______

A

Superoxide dismutase

57
Q

Copper deficiency leads to iron-deficiency anaemia because copper is a cofactor in _______

A

Ceruloplasmin

58
Q

Copper deficiency leads to hypopigmentation of hair and skin due to the role of copper in _______ enzymes

A

Tyrosinase

59
Q

Copper is involved in crosslinking of collagen and elastin as a cofactor of _______

A

Lysyl oxidase

60
Q

Manganese is found in the 2+ or ____ valence

A

3+

61
Q

Manganese is absorbed along the small intestine via simple diffusion, _____ or ZIP14

A

DMT1

62
Q

The presence of _______ facilitates manganese absorption

A

histidine

63
Q

Manganese is transported from the liver to tissues bound to _______, α2-macroglobulin or other globulins

A

transferrin

64
Q

25-40% of manganese in the body is found in _______

A

bone

65
Q

Mn is a cofactor to glycosyl and xylosyl transferases in the synthesis of _______ in connective tissue

A

Glycosaminoglycans

66
Q

Mn is a cofactor in arginase which cleaves arginine to form _______ and ornithine

A

urea

67
Q

Mn is a cofactor in pyruvate carboxylase and PEP carboxykinase in _______

A

gluconeogenesis

68
Q

Mn is a cofactor in the antioxidant enzyme _______

A

SOD2

69
Q

Manganese toxicity known as _______ results in severe neurological manifestations

A

Manganism

70
Q

Iodine content in food reflects regionally variable _______

A

soil content

71
Q

Iodine is found in food as _______ or iodide

A

iodate

72
Q

The absorption form of iodine

A

iodide

73
Q

Iodide is absorbed in the stomach and duodenum by active transport via _______

A

Sodium-iodide symporter

74
Q

Some foods contain _______ that interfere with iodine absorption or uptake into the thyroid gland

A

Goitrogens

75
Q

The main function of iodine is as a component of _______

A

thyroid hormones

76
Q

The most common thyroid hormone in the circulation

A

T4

77
Q

The most biologically active thyroid hormone

A

T3

78
Q

Iron-dependent enzyme that adds iodine to thyroglobulin

A

Thyroid peroxidase

79
Q

Selenium-dependent enzymes that convert T4 to T3 in cells

A

DIO

80
Q

T3 binds to nuclear receptors which bind to DNA to promote _______

A

gene expression

81
Q

Thyroid hormone stimulates _______ expenditure

A

Basal energy

82
Q

In adipose tissue, thyroid hormone enhances _______

A

Lipolysis

83
Q

In the bone, thyroid hormone promotes _______

A

Anabolism

84
Q

In terms of the cardiovascular system, thyroid hormone increases _______

A

heart rate

85
Q

The RDI for iodine (150ug) can be met by consuming ____ teaspoon/s of iodised salt

A

1/2

86
Q

Iodine deficiency results in _______ in adults

A

hypothyroidism

87
Q

Enlargement of the thyroid gland to trap more iodine is known as _______

A

Goiter

88
Q

When the mother is iodine deficient during pregnancy, this can lead to _______ in the infant

A

Neurological cretinism

89
Q

_______ and dairy products are good sources of iodine

A

seafood

90
Q

True or false: Australia has mandatory iodine fortification

A

true

91
Q

The selenium content of food depends on _______ concentration

A

soil

92
Q

Selenium is bound to _______ in plant foods

A

methionine

93
Q

Selenium is bound to _______ in animal foods

A

Cysteine

94
Q

Selenium is also found in lesser amounts as selenite and selenate in _______ foods

A

plant

95
Q

Seafood is generally an excellent source of selenium, however the presence of _______ inhibits its absorption

A

Mercury

96
Q

Selenium is transported to the _______ as free selenocysteine and selenomethionine

A

liver

97
Q

Selenium is exported from the liver primarily as ______

A

Selenoprotein P

98
Q

Selenium is stored in tissues as _______

A

Selenomethionine

99
Q

Selenium is a component of 25 proteins and enzymes as _______

A

Selenocysteine

100
Q

Selenium is a component of selenophosphate synthetase 2 needed for the synthesis of other _______

A

Selenoproteins

101
Q

Selenoprotein that functions as an antioxidant enzyme

A

Glutathione peroxidase

102
Q

Deiodinases are selenoproteins needed for the conversion of _______

A

T4 to T3

103
Q

Selenium deficiency leads to reduced _______ activity

A

thyroid hormone

104
Q

Chromium exists in food in the ____ valence

A

3+

105
Q

The highest concentrations of chromium are in the liver, spleen and _______

A

bones

106
Q

Chromium is released from food under _______ conditions

A

acidic

107
Q

Chromium is mainly transported bound to _______ and albumin

A

tranferrin

108
Q

While mechanisms are unclear, chromium seems to potentiate the action of _______

A

insulin

109
Q

True or false: plasma and urinary chromium concentrations are good indicators of chromium status

A

false

110
Q

Chromium deficiency leads to _______ resistance and elevated blood glucose and free fatty acids

A

insulin

111
Q

At high doses, chromium leads to renal failure, liver dysfunction and _______ damage

A

DNA

112
Q

Molybdenum is found in food as _______

A

molybdate

113
Q

Molybdate is absorbed via _______ and via a carrier

A

passive difffusion

114
Q

Molybdenum is transported bound to _______ or α2-macroglobulin

A

albumin

115
Q

Molybdenum is a cofactor to four enzymes as _______

A

Molybdopterin

116
Q

Molybdopterin is a cofactor in _______ which converts sulfite to sulfate

A

Sulfite oxidase

117
Q

Molybdopterin is a cofactor in _______ which hydroxylates purines, pyrimidines and pteridines

A

Xanthine oxidoreductase

118
Q

Molybdenum is involved in drug and toxin metabolism as a cofactor to _______

A

Amidoxime reductase

119
Q

Molybdenum is involved in retinal and pyridoxal metabolism as a cofactor to _______

A

Aldehyde oxidase

120
Q

Symptoms of gout have appeared in regions with high soil molybdenum content due to accumulation of _______ in joints

A

uric acid

121
Q
A

NUTR2101 (8 decks)

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