Minerals Flashcards
Define bioavailability
The degree to which the amount of an ingested mineral is absorbed and available to the body
What are factors altering mineral bioavailability?(4)
Deficiency of minerals
Chemical binding of mineral to other elements of diet
Excess of mineral
Presence of vitamins
Examples of mineral bioavailability altering (5)
Reduced storage will increase absorption of minerals from GI tract/kidney
Phytates in plants bind to minerals preventing absorption
Excess zinc decreases iron and copper absorption
Vitamin C presence increase zinc absorption
Vitamin D presence increases calcium absorption
Which minerals maintain osmotic pressure?(3)
Sodium
Chloride
Potassium
Minerals involved in skeletal structure (3)
Magnesium
Phosphorus
Calcium
Minerals involved in acid base equilibrium (pH) (3)
Phosphorus
Calcium
Magnesium
What is a metalloprotein?
Protein bound to metal
Examples of metalloproteins (3)
Haemoglobin
Myoglobin
Cytochromes
Major role of metalloenzymes
Regulate biological processes within the body
Examples of metalloenzymes (4)
Glutathione peroxidase
Carbonic anhydrase
Pyruvate carboxylase
Cerulolasmin ferroxidase
What can cause mineral deficiencies?(2)
Inadequate diet
Inability to digest mineral
Define metabolic deficiencies
Inability of the body to digest minerals from sites in the body or from diet
What is the major source of sodium in foods?
Sodium chloride
What are the roles of sodium (4)
Nerve conduction
Nutrient absorption and transport
Maintenance of membrane potential
Regulation of osmotic and electrolyte balance
What is the primary regulator of water intake
Thirst
Regulation of fluid and electrolyte balance (11)
Decreased blood pressure/blood volume
Kidneys release renin into circulation
Stimulates angiotensin 1 then angiotensin 2
Causes vasoconstriction
Angiotensin 2 also causes aldosterone to be synthesised by adrenal glands Kidneys increase reabsorption of sodium Increases water retention Increases blood volume Increases blood pressure
Low BP/BV increased ADH production from pituitary gland
Stimulates kidneys to increase water reabsorption
Increase BP
What is hypnotremia?
Decreases sodium concentration in blood plasma
What causes hyponaetremia?(3)
Excessive hypotonic sweating
Prolonged vomiting or diarrhoea
Diuretics
What is hypernatremia?
Increased sodium concentration in blood plasma
What causes hypernatremia?(3)
Excess fluid loss
Inadequate water intake
Renal failure causing excess sodium
Effects of excess sodium chloride?(5)
Hypertension Edema Stomach cancer Osteoporosis - excess calcium excretion Left ventricle hypertrophy
What is the average amount of iron in human body?(5)
2-4g
65% Haemoglobin
10% myoglobin
1-5% enzymes
Rest in blood and storage
Which oxidation states does iron exist in the human body?(2)
Fe2+ - ferrous, haem
Fe3+ ferric, non-haem
Which type of foods contains some heam iron?(3)
Meat, poultry and fish (also has non haem, veggies + fruit exclusively have non haem)
Roles of iron (4)
Oxygen transport
Cofactor for enzymes
Energy production
Pro-oxidant
How much of body weight is accounted for by minerals
4%
Examples of specific roles of iron (4)
Cofactor for enzymes - succinate dehydrogenase in TCA cycle
Pro-oxidation - lipid peroxidation
Energy production - cytochrome contains haem which transports election through ETC
Oxygen transport - control to Haemoglobin structure
Iron absorption (7)
Dietary non-haem (Fe3+) is reduced to Fe2+ for transport across the apical brush border
Uses divalent metal transport 1 (DMT1)
Dietary haem iron is transported across border by Haem Carrier Protein 1
Haem is released from a bigger dietary haem structure by haem oxygenase
Some iron stored in ferritin
Ferroportin exports some iron for it to be incorporated into serum transferrin
What is a mineral?(3)
Building blocks of rocks
Inorganic nutrients
Present in the soil, rocks and water
Describe ferritin (3)
Iron storage protein found in all cells
Stores ferric iron (Fe3+)
Amount of ferritin directly reflects amount of iron in body
Describe transferrin (3)
Glycoprotein synthesised in the liver
Ferric iron is transported in blood bound to transferrin
Delivers iron to site of storage or utilisation
What increases haem absorption (2)
Low iron status
Low haem iron intake
What increases non haem absorption (5)
Depleted iron status Pregnancy Vitamin C (ascorbic acid) Meat, Fish, seafood Anaemia
What decreases haem absorption (3)
High iron status
High haem iron intake
Calcium
What decreases non haem absorption (5)
Replete iron status Low gastric acid Phytates Iron-binding phenolic compounds Calcium
3 stages of iron deficiency
Depletion of strange iron - decreases in serum ferritin
Decrease in transport iron
Decrease in iron for Haemoglobin for new blood cells
Effects of iron deficiency (4)
Fatigue
Anaemia
Poor cognitive development in babies
Babies born with poor motor skills
Where is iodine found?(3)
Rocks
Seawater
Some soils
Good sources of iodine (2)
Seaweed
Seafish
Iodine absorption (3)
Rapidly absorbed in the gut
Distributed throughout whole body
Excess excreted in urine
On average how much iodine is present in humans
20-30 mg
Roles of iodine (7)
Thyroid hormone synthesis in thyroid gland
Thyroid hormones regulates: metabolic rate Thermogenesis Growth and development Blood cell production Nerve and muscle function Modulates gene expression by binding to receptors
Iodine deficiency (3)
Many people affected worldwide
Causes goitre - swelling in neck
Can cause mental retardation - lower IQ points
What is goitre (3)
Enlargement of thyroid glands
Causes by iodine deficiency - under 50 mg per day
Reversible with iodine treatment
What is cretinism (4)
Due to iodine deficiency prior to birth
Neurological syndrome - mental retardation
Stunts growth
Irreversible
What can affect iodine bioavailability
Goitrogens
How do goitrogens affect bioavailability (4)
Reduce iodine metabolism by reducing iodine uptake
Reduce synthesis of thyroid hormone
Reduce release of hormone from gland
May compete with iodide for uptake by thyroid gland
Examples of goitrogens (2)
Thiocyanates
Cyanogenic glycosides
What causes iodine toxicity
Over 2g a day over a prolonged time
Selenium food sources (5)
Seafoods Organ meats Cereals and grains Dairies Brazil nuts
Which selenium source is more bioavailable
Plant sources
Differences in absorption of organic and inorganic selenium (4)
Organic - actively transported, more rapidly absorbed
Inorganic - passively absorbed, slower absorption
Which proteins are selenium typically bound to in the blood (2)
VLDL
Albumin
Food sources of calcium (3)
Dairies
Sardines with bones
Fortified products
Factors that improve calcium absorption (3)
Vitamin D
Lactose containing foods ingested at the same time
Sugar alcohols
Factors that inhibit calcium absorption (8)
Fibre Phytates Oxalates - found in spinach and squash High sodium High protein High caffeine Soda - phosphoric acid Tannin - in tea
Roles of calcium (5)
Bones and teeth Neuronal transmission Blood clotting Muscle contraction/relaxation Cofactor for enzymes
Food sources of phosphorus
Same foods as calcium
How does vitamin D regulate low calcium and phosphorus availability in the blood (3)
Stimulate increased absorption from GI tract
Increase retention at kidney
Withdrawal from bones to blood (resorption)
How does PTH regulate calcium (4)
Increase bone resorption
Increase kidney reabsorption
Increase PO4 excretion
Increase calcium absorption from small intestine by synthesising calcitrol from kidney
What is 1,25(OH)2D and its roles (5)
Metabolite of vitamin D produced in kidney increase blood calcium by promoting absorption of dietary calcium from GI tract
Increases calcium reabsorption
Increases release of calcium from bone
Inadequate dietary calcium consequences (3)
Maintain blood calcium at expense of bones
Osteoporosis - low BMD
Osreomalcia - rickets in children
What are minerals classified by?(2)
Requirement
Tissue amount
What classes as a macro mineral (2)
Over 5g found in body
Over 100mg needed a day
What classes as a micro mineral (2)
Under 5g in body
1-100 mg needed a day
Trace mineral (2)
Trace amount found in body
Under 1mg needed a day
What happens if their a high levels of trace mineral in the body?(2)
Become chemically reactive
Becomes toxic
What is the most common mineral deficiency
Iron
What vary mineral requirements?(5)
Pregnancy Lactation Growth Frequency activity Gut parasites
What causes hidden hunger (4)
Poor food security
Geographical location
Food processing
Metabolic deficieny
How can geo location affect diet(2)
Soil content of mineral is variable
Problematic for those who are dependent on local food
Why must iron be bound to protein
Free iron is toxic
Examples of how food processing can lead to an improper diet (5)
For example increase salt content to make foods more palatable
Increased sodium results in increased secretion - loss of calcium
Food preparation can reduce minerals - peeling and boiling
Milling of grains to refine them
Mechanisms to prevent iron toxicity (3)
Storage - bound to ferritin
Recycle iron to make new blood cells
Regulate amount of iron that is absorbed
What greatly impacts selenium concentrations in food sources?
Selenium soil concentration - influences intake
What is selenium converted to after being absorbed (2)
Selenophosphate then selenocysteine
Selenium anti oxidant mechanism (5)
Vitamin E donates electron to stabilise free radical and protect cell membrane
Vitamin E becomes a radical
glutathione donates electron to vitamin E so it can be regenerated
This requires glutathione peroxidase which contain selenium
Glutathione is regenerated by vitamin C (absorbed acid)
Consequences of selenium deficiency (3)
Kashin-beck disease
Osteoarthropathy
Keshan disease
Selenium toxicity symptoms (3)
Skin lesions
Garlic breath
Brittle hair and nails
Calcium regulation when calcium is high (3)
High plasma calcium stimulates an increase in calcitonin from thyroid
Inhibits bone resorption and calcium reabsorption
This decreases plasma calcium
Calcium regulation when plasma levels are low (7)
Increase in PTH and vitamin D
Increases absorption, reabsorption, resorption and PO4 renal excretion
Thus increases plasma calcium levels
What are DRVs determined to achieve for minerals (2)
Maintain a given circulating level/ tissue concentration
Absence of signs of deficiency disease
What is the most abundant cation + and anion - in the body?
Sodium
Chloride
Variable sources of iodine (3)
Plants
Cereals
Dairies
What is iodine absorbed as?
Iodide
What percentage of iodide is in the thyroid gland?
80%
Metalloenzyme associated with iron and its function
Succinate dehydrogenase
TCA Cycle
Metalloenzyme associated with copper and its functions
Ceruloplasmin ferroxidase
Iron utilisation
Copper transport
Metalloenzyme associated with zinc and its function
Carbonic anhydrase
CO2 formation
Metalloenzyme associated with manganese and its function
Pyruvate carboxylase
Pyruvate metabolism (TCA cycle)
Example of macro minerals (6)
Calcium Phosphorus Sodium Potassium Chloride Magnesium
Examples of micro minerals (6)
Iron Zinc Copper Selenium Iodine Manganese
Cereals with medium iron bioavailability
Corn flour
Cereals with low iron bioavailability (3)
Maize
Wholemeal flour
Rice
Fruits with low iron bioavailability (2)
Apples
Bananas
Fruits with medium iron bioavailability
Pineapple
Fruits with high iron bioavailability (2)
Orange
Lemon
Vegetables with medium iron bioavailability (2)
Carrot
Potatoes
Vegetables with low iron bioavailability (2)
Soya
Legumes
Vegetables with high iron bioavailability (2)
Cabbage
Broccoli
Nuts have ______ iron bioavailability
Low
Animal products with low iron bioavailability (3)
Cheese
Cow milk
Eggs
Animal products with high iron bioavailability (4)
Meat
Fish
Poultry
Breast milk
Examples of ferrous (Fe2+) supplements (2)
Ferrous sulphate
Ferrous fumarate
Iodine toxicity symptoms (6)
Fever Burning sensations Vomiting Diarrhoea Nausea Coma
Rich sources of selenium (2)
Organ meats
Seafoods
What percentage of selenium is absorbed in the small intestine?
50-80
In which tissues have the highest iodine concentrations?(3)
Thyroid glands
Saliva glands
Gastric glands
Food sources of thiocyanates (3)
Cabbage
Kale
Sprouts
Food source cyanogenic glycosides
Cassava
