Minor Minerals Flashcards
Zinc absorption is influenced by a variety of factors. Which of the following increase zinc bioavailability for absorption?
pick 2
- Non-heme iron
- Low to moderate zinc concentration in food or supplements
- Presence of yeast in grain sources of foods
- Large concentration of zinc in food or supplement
- Zinc consummed from whole grains
- Zinc sufficiency status
- Low to moderate zinc concentration in food or supplements
3. Presence of yeast in grain sources of foods
A deficiency of selenium results in a deficiency of [A] overtime
A deficiency of selenium results in a deficiency of Correct Iodine function overtime
Which of the following is a symptom of zinc deficiency? from the following
- Increased taste sensitivity
- Poor wound healing
- Increased sperm count and motility
- Megaloblastic anemia
- Goiters
Poor wound healing
Which of the following population groups is at highest risk of iron-deficiency anemia?
1. Menopausal women
- Newborn babies
- Builders and carpenters
- Vegetarian dieters
- Weight-training athletes
- Vegetarian dieters
The proteins ____________ oxidize ferrous iron to ferric iron.
1. Heme and non-hemeoxygenase
- Hephaestin and ceruloplasmin
- Ferritin and albumin
- Ferroportin and hepsidin
- Hemosiderin and ferritin
Correct Hephaestin and ceruloplasmin
Which type of dietary iron is most efficiently absorbed?
1. Ferrous
- In Fe3+ form
- Elemental iron
- Non-heme iron
- Ferric
- Ferrous
Zinc induces the synthesis of metallothionein, which:
Answers:
1. Is a zinc-containing enzyme in the antioxidant defence network
- Slows down the entry of zinc into the blood stream
- Increases the bioavailability of zinc to cells
- Is the primary protein carrier of zinc in the blood
- Is the storage form of zinc in the liver
Correct2.
Slows down the entry of zinc into the blood stream
Zinc induces the synthesis of metallothionein, which:
Answers:
1. Is a zinc-containing enzyme in the antioxidant defence network
- Slows down the entry of zinc into the blood stream
- Increases the bioavailability of zinc to cells
- Is the primary protein carrier of zinc in the blood
- Is the storage form of zinc in the liver
2.
Slows down the entry of zinc into the blood stream
Goitrogenic foods that can inhibit iodine metabolism include:
- Raw cabbage, broccoli and cauliflower
- None of these are goitrogenic foods
- Cooked sprouts, lettuce and capsicums
- Cooked cabbage, broccoli and cauliflower
- Raw sprouts, lettuce and capsicums
1.
Raw cabbage, broccoli and cauliflower
Transferrin
Transports iron to tissues
Hephaestin
Converts Fe2+ to Fe3+ in the basolateral membrane of enterocytes, for transport
Ferrireductase
Converts Fe3+ to Fe2+ in brush border of enterocytes for absorption
Hemosiderin
Stores iron in organs
Cerruloplasmin
Converts Fe 2+ to Fe3+ in the blood circulation, for transport
The transport of iron out of the intestinal cell for incorporation into serum transferrin is facilitated by ___________and the conversion to ____________by _____________.
1.
Hephaestin; ferric iron; ferroportin
- Hepcidin; ferric iron; ferroxidase.
- Ferroportin; ferric iron; hephaestin
- Hepcidin; ferric iron; ferroportin.
- Hepcidin; ferous iron; ferroportin
Ferroportin; ferric iron; hephaestin
The signs/symptoms of copper deficiency include:
Osteopenia, anemia, low white blood cells count
The biologically active form of selenium is
Selenocysteine:
Iron is stored in the liver and organs as:
Ferritin and hemosiderin
Neurological cretinism seems to have re-appeared in Australia due to reduced positive contamination opportunities.
T OR F
T
Which of the following is associated with copper toxicity?
Answers:
1.
Hemochromatosis
- Keshan’s disease
- Grave’s disease
- Wilson’s disease
- Lou Gehrig’s disease
4.
Wilson’s disease
When body cells need more iron:
Answers:
1.
Hepcidin production is upregulated
- The number of transferrin receptors on cell membranes increases
- The number of trasferrin receptors on cell membranes remains unchanged
- The number of transferrin receptors on cell membranes decreases
- More enteral cells are sloughed off
The number of transferrin receptors on cell membranes increases
The “mucosal block” theory explains how the body protects itself from excess absorption of dietary minerals, such as:
Answers:
1.
Fluoride
- Calcium
- Manganese
- Iodine
- Zinc
Zinc
Zinc is involved in all of these functions except:
Answers:
1.
Alcohol metabolism
- Enzymatic antioxidant system
- Blood glucose homeostasis
- Digestion
- Vitamin receptors stabilisation
3.
Blood glucose homeostasis
The mechanism by which fluoride is involved in dental health is understood to be
Increasing the teeth protective layer from bacteria
In iron-deficiency anemia, the red blood cells are usually classified as:
Answers: 1. Similar to B12 deficiency anemia 2. Microcytic and hypochromic 3. Microcytic and hyperchromic
- Normocytic and hypochromic
- Megaloblastic and hypochromic
Microcytic and hypochromic
Which of the following best describes the sequence of events leading to the development of goiter in iodine deficiency?
- Low circulating iodine; decreased secretion of TSH; hyperplasia and hypertrophy of thyroid tissue
- Low circulating TSH; increased secretion of T4; hyperplasia and hypertrophy of thyroid tissue
- Low circulating T4; increased secretion of TSH; hyperplasia and hypertrophy of thyroid tissue
- Low circulating TSH; increased secretion of T3; hyperplasia and hypertrophy of thyroid tissue
- Low circulating T3; increased secretion of TSH; hyperplasia and hypertrophy of thyroid tissue
Correct3.
Low circulating T4; increased secretion of TSH; hyperplasia and hypertrophy of thyroid tissue
Manganese activity includes all the following except: [A]
Selected Answer:
Manganese activity includes all the following except:
All Answer Choices Cofactor in gluconeogenesis Cofactor in redox homeostasis Cofactor in alcohol metabolism Cofactor in wound healing Cofactor in bone proteins formation Cofactor in cholesterol synthesis
Correct Cofactor in alcohol metabolism
Which of the following enzymes are copper dependant?
Superoxide dismutase, cerruloplasmin
What are the minor minerals? what are their major functions?
Iron - hemoglobin, respiration, immune, cognitive development, energy metabolism -fatigue anemia
Zinc - immune function, growth and development, stabilize cell membranes and body proteins - dermatitis diarrhea, decreased apatite and taste, infection poor growth and development
Copper - aids iron mtabolism, antioxidant enzymes, involved conective tissue metabolism - anemia , low white blood cell count , poor growth
Manganese - cofactor several enzymes, involved carb metabolism and antioxidant protector - poor growth, skeletal abnormalities
Iodine - thyroid hormone component, basal metabolims growth and development- goiter, cretinism
Selenium- part antioxidant system as glutathione peridoxase activates thyroid hormones - Keshan disease reduced thyroid hormone
Chromium- enhance insulin action - glucose intolerance
Fluride- increase resistance tooth enamel - dental risk
Molybdenum- cofactor several enzyme- unknown
iron functions, risks, sources
Iron - hemoglobin, respiration, immune, cognitive development, energy metabolism -fatigue anemia
RISK - children, pregnant
Meat, seafood, eggs, fortified
other
the rest are rare
iodine - if not fortified
selenium if not in soil
2 types iron
Heme iron (ferrous iron): Fe2 +, found in hemoglobin and myoglobin of animal
fleshNon-heme iron (ferric iron): Fe3 +, iron found in plant foods, grains, supplements
(supplements can also come in the ferrous form), some minor amounts in meat
Iron cookware can also contribute to iron intake (important source for
populations in developing countries, or when dietary iron sources are scarce)
In humans: Fe2+ for absorption, Fe3+ for transport
factors effect bioavalibility
Bioavailability
Plants sources (in Fe3+ ) contain factors interfering with iron absorption, even in iron
enriched products:
Phytic acid, oxalic acid, polyphenols, excess fibre
Meat, fish, HCl and ascorbic acid enhance
non-heme iron absorption when consumed
together => conversion to Fe2 + for adequate absorption
Zinc toxicity
Toxicity
• Anorexia, nausea, vomiting, intestinal cramps, diarrhea
• Reduced Cu bioavailability (metallothionein); competition
with Fe absorption
• Impaired immune function
Zinc Deficiency
ZINC REQUIREMENTS
Deficiency
• Anorexia (= loss of appetite)
• Dermatitis, impaired vitamins A, D and thyroid hormone
function, alopecia, poor wound healing
• Delayed growth, poor development in children
• Decreased taste
• Decreased immune function
Note: alcohol excess intake increases Zn requirement for its
metabolism (alcohol dehydrogenase) + increases excretion
via urine
Zinc Functions
1) Zn is a cofactor to over 300 enzymes
- From every enzyme class (oxidoreductases, hydrolases, lyases, isomerases,
transferases, and ligases)
- Zn Binds amino acid residues and stabilizes the enzyme’s tertiary structure, and/or
- Zn Participates in the reaction at the catalytic site
- Zn-dependent enzymes are involved in:
o Protein, carbohydrate, lipid, nucleic acid and alcohol metabolism
o Growth and development
o Immune response
o Antioxidant defence
o Neurological function
o Reproductive function
2- Zinc is a cofactor to transcription factors
• Over 2,000 transcription factors require zinc
• The binding of zinc to transcription factors
results in a conformational change that
resembles a “finger”
• Zinc fingers interact with metal response
elements (MREs) located in the promoter
region of genes to enhance or repress
transcription
• The nuclear receptors that bind estrogens,
thyroid hormones, vitamin A and vitamin D
are examples of zinc finger proteins
• => Decreased thyroid hormone and BMR
observed in zinc-restricted diets
nc
Zinc cofactor Enzymes
Alcohol dehydrogenase: alcohol
• Converts alcohol to acetaldehyde; also converts retinol to retinal
• Contains 4 zinc atoms per enzyme – 2 involved in catalytic activity, 2 stabilise protein structure
Carboxypeptidases A and B: protein digestion
• Secreted by pancreas and involved in protein digestion
• Enzymatic activity decreases with zinc deficiency => poor protein digestion
Polyglutamate conjugase: folate digestion
• Catalyses the removal of glutamic acids from folate => poor zinc status can diminish folate
absorption
Superoxide-dismutase: antioxidant
• Catalyses the removal of superoxide radicals: 2O2• + 2 H+ → H2O2 + O2
• SOD1 and SOD3 are zinc and copper dependent: Zn plays a structural role, Cu is catalytic
Matrix metalloproteinases: wound healing
• Degrade components of the extracellular matrix to allow for remodelling of extracellular
matrix proteins and tissue repair
• Zinc located at the catalytic site where the substrate binds
Iodine deficiency
Deficiency
Iodine deficiency disorders (IDD) = goiter
and neurological cretinism
Goiter: when T4 level drops, increased TSH
secreted, thyroid enlarges to trap more
iodine;
Low T3 =>slowed metabolism
Neurological cretinism: irreversible mental
retardation, loss of hearing & speech
abilities, short stature, neurological disorder,
muscle spasticity in the future child.
Occurs when the mother is deficient in
iodine during pregnancy, breastfeeding, or
when deficiency is maintained during early
childhoodHypothyroidism in adults:
Effects of hypothyroidism are more
subtle in the brains of adults than
children: low educability, apathy, and
reduced work productivity.
Other symptoms: fatigue, weight gain,
cold intolerance, constipation.
WHO’s mission was to eradicating iodine
deficiency in the decade to 2020 (fortified
salt, iodine oil, & fortified milk interventions)
Iron Toxicity
Toxicity
• Nausea, vomiting, stomach irritation,
impaired absorption of other minerals
• Hemochromatosis: genetic disorder where
the “mucosal block” (ferritin storage) does
not function adequately
• Ferroportin is not regulated: despite
high iron level, more is exported to the
blood and taken to tissues
• Iron deposits and overload in liver, heart
• If not managed, leads to liver cirrhosis,
heart failure, elevated oxidative stress
markers
• Management includes: regular blood
“letting”, dietary advice to reduce high iron
containing foods, chelation therapy
iron deficiency
Deficiency • Iron-deficiency anemia = microcytic hypochromic anemia
(decreased hemoglobin); decreased hematocrit (% blood
volume containing RBCs), decreased serum ferritin*,
transferrin receptors number on cells increases
• Symptoms: shortness of breath, fatigue with usual tasks,
compromised immunity, depression, spoon
-shaped nails
• Most common minor mineral deficiency worldwide • At risk: premature infants, children, child-bearing age
women, vegetarians & vegans, regular blood donors,
gastric ulceration
• If during growth and development: impaired cognitive
development that may be irreversible
•
Symptoms may be few initially when diet is changed (e.g.
limiting iron sources) =>
iron stores are being used up
functions of iron
1- Oxygen delivery
Hemoglobin: Found in red blood cells,
transports O2 and CO2, 4 x Fe-containing heme
groups which bind 1 oxygen each
Myoglobin: found in skeletal and cardiac
muscle, stores O2 , 1 x Fe-containing heme
group binds 1 oxygen
2- Oxidation – reduction reactions
=> Can be harmful in high concentration, as
iron forms free radical compounds
Fe2+ + H2O2 Fe3+ + OH- + •OH (hydroxyl radical)
3- Immune function
required for lymphocytes and natural killer cells
production
4- Iron-containing metalloenzymes
What are some examples you have come across?
5- Energy metabolism
Involved in the first steps of the CAC and as cofactors
of cytochromes in the electron transport chain
6- Alcohol and drug metabolism
Hepatic cytochrome p450 detoxification system
enzymes and catalase require iron as co-factors
7- Neurotransmitter synthesis
Cofactor in enzymes involved in synthesis of dopamine,
epinephrine, norepinephrine, serotonin
WHat do DMT1 HPC1 do Ferrireductase Ferritin Feroportin Hepicidin Hephaestin Ceruloplasmin Transferrin Lysosomes
Small Intestine Fe2+ DMT-1 and HCP-1 (1st enter the)
Brush Boarder Ferrireductase converts fe3+ to Fe2+ (reductase REdUE 3 to 2)
Mucosal block = Ferritin: prevents excess absorption binds and stores iron in
enterocytes (and other tissues)
Ferroportin= transport iron out (trnasPORTIN)
Hepcidin regulates (regulates everything only one not F)
Convert fe2+ to fe3+ (oxidise) Hephaestin in
enterocytes and ceruloplasmin in the
blood
Transported as Fe3+ bound to Transferrin (TRANSFER after transPORT)
uptake endocytosis lysosomes release iron and transferren is recycled
Describe absorption of iron from absorption to transportation
Absorption
• As Fe2+ in small intestine, mediated by carrier
proteins (DMT-1 and HCP-1)
• Efficiency depends on body’s iron status
(average 18%; range 14 - 40%)
• HCl in stomach and vitamin C enhance absorption
by conversion of Fe3+ to Fe2+ form
Ferrireductase: enzyme in the brush-border also
converts Fe3+ to Fe2+
Excessive intake of calcium, zinc, phosphorus,
manganese may chelate iron and interfere with its
absorption
Storage/carrier proteins in the enterocyte • Ferritin: binds and stores iron in enterocytes (and other tissues) • Iron does not enter bloodstream if body’s iron stores are high • Ferritin prevents excess absorption => “mucosal block” Ferroportin: transports iron out of enterocytes when supplies are low for release into the blood • Hepcidin: regulates how much iron is released into the circulation Ferroxidase enzymes: Hephaestin in enterocytes and ceruloplasmin in the blood (both copper-dependent metalloenzymes) convert Fe2+ to Fe3+ • Transported as Fe3+ bound to transferrin • In tissues cells: uptake by endocytosis; lysosomes release the iron, and transferrin is recycled
