Week 11 revision questions Flashcards

1
Q

Difference between major and minor minerals

A
  • major >100mg per day

- minor <100mg per day

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2
Q

major minerals

A
  • Sodium
  • Potassium
  • Chloride
  • Calcium
  • Phosphorus
  • Magnesium
  • sulfur
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3
Q

Influences mineral conc in food

A
  • genetic variation in animals (absorption pathways of nutrients from soils and feed)
  • variation in mineral content in soil
  • in refined pllant produces - milling removes iron, selenium, zinc and copper etc
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4
Q

Factors impairing mineral bioavailability

A

o Excess fibre (above 38g/day) can lead to lower mineral status
- Phytic acid found in fibre (phytate in legumes and whole grains): binds to minerals & leads to excretion

  • Oxalic acid in dark green leafy vegetables (not associated with fibre) : binds minerals and makes them less bioavailable E.g. calcium in spinach: 5% absorbed versus 32% for calcium from dairy
  • Polyphenols and tannins can reduce bioavailability of iron and calcium in particular e.g. black tea, dark chocolate, red wine (all contain high levels of tannins that interfere with iron absorption)
  • antacids may impair bioavailability of minerals, because of reduced stomach acidity
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5
Q

Factors facilitating/increasing mineral bioavailability

A
  • Vitamin C: improves non-haem iron absorption within the same meal
  • Stomach acidity: assists in converting minerals from 3+ to 2+: helps their absorption (as 2+ is the absorption form od minerals)
  • Leavened breads with baker’s yeast may break the bonds between the phytates and the minerals: ↑ bioavailability of minerals
  • Good vitamin D status facilitates dietary calcium absorption (because vitamin D receptor and calcitriol are involved in the active transport of calcium absorption)
  • Human absorption of minerals increases when needs are greater
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6
Q

Main anion and cation in ECF

A

cation - Sodium

anion - chloride

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7
Q

Main anion and cation in the ICF

A

cation - Potassium

anion - phosphorus

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8
Q

Sodium comes from the diet

A

1 - processed foods 77%
2 - naturally occuring 12%
3 - added to food on plate 6%
4 - added to food during cooking 5%

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9
Q

Conversion of sodium to salt

A

/0.393

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10
Q

conversion of salt to sodium

A

*0.393

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11
Q

hypertension

A

Chronic elevation of blood pressure (pressure exerted by blood flow against blood vessels measured in mm Hg

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12
Q

DASH

A

Dietary approach to stop hypertension

- high potassium to sodium ratio (4700mg:2300mg)

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13
Q

major functions of calcium with their mechanism

A
  1. Bone development and maintenance:
    - Forms calcium-hydroxyapatite along with phosphate
    2- Blood clotting: calcium involved in the blood clotting factors formation cascade. Ca binds to the gamma carboxy glutamic acid in prothrombin
  2. Muscle contraction:
    - Calcium ions released when nerve impulse reaches myocytes
    - Calcium triggers muscle proteins to contract
  3. Transmission of nerve impulses
    Influx of calcium ions when nerve impulse reaches cell
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14
Q

How can potassium assist in reducing hypertension in salt sensitive people?

A

by trying to achieve high potassium to soidum ratio to induce excretion of sodium->excretion of water->reduce blood volume->reduce hypertension ???

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15
Q

Is having a high calcium diet the only factor for good bone density?

A

nope bone building nutrients include more than calcium: potassium, vitamin D, vitamin K, protein, magnesium, vitamin C, phosphorus, copper as well as exercise

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16
Q

Contrast/compare a typical high sodium with a high potassium diet, based on the kind of foods they would contain, and their nutrient density

A

Sodium
high in processed foods, low nutrient density, low in fibre.

Potassium
high in fresh unprocessed and whole foods, nutrient dense, high in fibre.

17
Q

nutrients important in bone health

A

Potassium - stops Ca++ excretion (acid base balance -> preventsCa2+ being used as buffer)
Calcium,magnesium and phosphate- form calcium hydroxyapatite to form collage
magnesium
Vit K - cofactor in carboxylation reaction for bone protein
Vit D - enhances calcium absorption
Vit C - cofactor in hydrolase enzyme involved in collagen formation
Protein - amino acid provision for collagen and bone protein

18
Q

How does the DASH aim to address hypertension?

A
  1. high potassium to sodium ratio to induce excretion of sodium -> excretion of water -> reduce blood volume -> reduce hypertension
  2. calcium can act as a smooth muscle relaxant
  3. magnesium can act as a vasodilator
    2 and 3 make blood vessels more flexible and adapt to blood volume thus reduce blood pressure
  4. fibre - helps cholester to bind to bile so excrete it -> dont reabsorb it -> forces body to produce more bile -> need to use blood cholesterol and therefore minimilising cholesterol absorption
    - also appetite control
19
Q

know mechanism by which calcium homeostasis is maintained in body - low level

A

low level -> parathyroid gland produces PTH -> promotes bone reabsorption -> increases synthesis of calcitriol -> increase calcium absorption in SI ->normal

20
Q

know mechanism by which calcium homeostasis is maintained in body - high level

A

high level -> thyroid gland produces calcitonin -> stops bone absorption -> promotes excretion of calcium through kidney -> normal

21
Q

Phosphorous absorption is promoted by

A

hormone calcitriol

22
Q

oxalic acid found in

A

green leafy vegetables - bind to minerals and impair absorption by decreasing bioavailibility

23
Q

phytic acid found in

A

fibre - bind to minerals and impair absorption by increasing excretion

24
Q

calcium is more bioavailable in

A

dairy foods