Week 11 revision questions

Question 1

Difference between major and minor minerals

Answer 1

• major >100mg per day

- minor <100mg per day

Question 2

major minerals

Answer 2

• Sodium
• Potassium
• Chloride
• Calcium
• Phosphorus
• Magnesium
• sulfur

Question 3

Influences mineral conc in food

Answer 3

• 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

Question 4

Factors impairing mineral bioavailability

Answer 4

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

Question 5

Factors facilitating/increasing mineral bioavailability

Answer 5

• 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

Question 6

Main anion and cation in ECF

Answer 6

cation - Sodium

anion - chloride

Question 7

Main anion and cation in the ICF

Answer 7

cation - Potassium

anion - phosphorus

Question 8

Sodium comes from the diet

Answer 8

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

Question 9

Conversion of sodium to salt

Answer 9

/0.393

Question 10

conversion of salt to sodium

Answer 10

*0.393

Question 11

hypertension

Answer 11

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

Question 12

DASH

Answer 12

Dietary approach to stop hypertension

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

Question 13

major functions of calcium with their mechanism

Answer 13

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

Question 14

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

Answer 14

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

Question 15

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

Answer 15

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

Question 16

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

Answer 16

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

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

Question 17

nutrients important in bone health

Answer 17

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

Question 18

How does the DASH aim to address hypertension?

Answer 18

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

Question 19

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

Answer 19

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

Question 20

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

Answer 20

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

Question 21

Phosphorous absorption is promoted by

Answer 21

hormone calcitriol

Question 22

oxalic acid found in

Answer 22

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

Question 23

phytic acid found in

Answer 23

fibre - bind to minerals and impair absorption by increasing excretion

Question 24

calcium is more bioavailable in

Answer 24

dairy foods