Week 11 revision questions Flashcards
Difference between major and minor minerals
- major >100mg per day
- minor <100mg per day
major minerals
- Sodium
- Potassium
- Chloride
- Calcium
- Phosphorus
- Magnesium
- sulfur
Influences mineral conc in food
- 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
Factors impairing mineral bioavailability
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
Factors facilitating/increasing mineral bioavailability
- 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
Main anion and cation in ECF
cation - Sodium
anion - chloride
Main anion and cation in the ICF
cation - Potassium
anion - phosphorus
Sodium comes from the diet
1 - processed foods 77%
2 - naturally occuring 12%
3 - added to food on plate 6%
4 - added to food during cooking 5%
Conversion of sodium to salt
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conversion of salt to sodium
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hypertension
Chronic elevation of blood pressure (pressure exerted by blood flow against blood vessels measured in mm Hg
DASH
Dietary approach to stop hypertension
- high potassium to sodium ratio (4700mg:2300mg)
major functions of calcium with their mechanism
- 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 - Muscle contraction:
- Calcium ions released when nerve impulse reaches myocytes
- Calcium triggers muscle proteins to contract - Transmission of nerve impulses
Influx of calcium ions when nerve impulse reaches cell
How can potassium assist in reducing hypertension in salt sensitive people?
by trying to achieve high potassium to soidum ratio to induce excretion of sodium->excretion of water->reduce blood volume->reduce hypertension ???
Is having a high calcium diet the only factor for good bone density?
nope bone building nutrients include more than calcium: potassium, vitamin D, vitamin K, protein, magnesium, vitamin C, phosphorus, copper as well as exercise