Module 3 wk 12 Flashcards
explain where iron is found in food , and in what form
heme iron (ferrous iron): Fe2+, found in hemoglobin and myoglobin of food products from animal source
non-heme iron (ferric iron): Fe3+, found in plant and grain food products (and minor amounts in meat)
why is iron in plant products less bioavailable?
must be converted from 3+ to 2+ valence for absorption
and
plant products also contain factors interfering with iron absorption, even in iron-fortified foods, phytic acid, oxalic acid, polyphenols, fibre
explain how goitre develops in iodine deficiency
T4 and T3 level drop -> TSH secretion increases, thyroid gland enlarges to trap more iodine. Low T3 -> symptoms of hypothyroidism
What are the dietary recommendations you give to a vegan consumer about trace minerals (keyword: dietary)
Iron
Sources: Lentils, chickpeas, beans, tofu, fortified cereals, spinach, quinoa, and pumpkin seeds.
Enhancement Tips:
Vitamin C: Consume vitamin C-rich foods (citrus fruits, bell peppers, tomatoes) with iron-rich meals to enhance non-heme iron absorption.
Avoid Inhibitors: Limit intake of calcium-rich foods, tea, coffee, and high-phytate foods around meals high in iron to prevent absorption inhibition.
Zinc
Sources: Whole grains, legumes, tofu, tempeh, nuts (cashews, almonds), seeds (pumpkin, sunflower), and fortified cereals.
Enhancement Tips:
Soaking and Sprouting: Soak or sprout legumes, grains, and seeds to reduce phytate levels and enhance zinc absorption.
Fermentation: Include fermented foods (miso, tempeh) which can improve zinc bioavailability.
Selenium
Sources: Brazil nuts (a single nut can meet daily requirements), sunflower seeds, brown rice, whole wheat bread, and mushrooms.
Moderation: Be cautious with Brazil nuts to avoid excessive selenium intake; one to two nuts per day is typically sufficient.
Copper
Sources: Whole grains, nuts (cashews, almonds), seeds (sesame, sunflower), legumes, dark chocolate, and mushrooms.
Balance with Zinc: Ensure a balanced intake of zinc and copper, as high zinc levels can interfere with copper absorption.
Manganese is generally sufficient in a varied vegan diet.
A varied vegan diet typically provides adequate molybdenum.
Chromium is usually adequate in a balanced diet focused on whole, unprocessed foods.
list the minerals studied that are involved in good bone health, and their respective roles
- Calcium
Calcium is the primary mineral in bones, giving them strength and structure. It forms hydroxyapatite crystals that provide rigidity to the bone matrix.
Bone Remodeling: Calcium is essential for the constant process of bone remodeling, involving resorption by osteoclasts and formation by osteoblasts. - Phosphorus
Bone Formation: Phosphorus is a key component of hydroxyapatite, the mineral complex that makes up bone and tooth enamel.
Bone Strength: It works with calcium to strengthen bones and teeth. - Magnesium
Bone Matrix Development: Magnesium is involved in the structural development of bone, with about 60% of the body’s magnesium stored in the bones.
Calcium Metabolism: It plays a role in regulating calcium levels, ensuring proper mineralization of bones. - Fluoride
Bone Mineralization: Fluoride helps in the mineralization of bones and teeth by forming fluorapatite, which is more resistant to demineralization than hydroxyapatite.
Dental Health: Fluoride is crucial in preventing dental caries by enhancing the strength and resilience of tooth enamel.
- Potassium
Acid-Base Balance: Potassium helps to neutralize acids in the body, which can otherwise lead to bone demineralization. It helps maintain a proper acid-base balance, protecting bone density.
Bone Preservation: Adequate potassium intake is associated with reduced calcium loss from bones and improved bone health.
- Zinc
Bone Growth and Development: Zinc is essential for bone growth and development. It is involved in the synthesis of collagen and the formation of the bone matrix.
Enzyme Function: Zinc is a cofactor for enzymes that play a role in bone mineralization. - Manganese
Bone Formation: Manganese is necessary for the formation of bone cartilage and bone collagen. It acts as a cofactor for enzymes involved in bone formation and metabolism.
Bone Density: It supports the structural integrity and density of bones.
describe the concept of the mucosal block in the context of trace minerals
The mucosal block is a crucial mechanism that helps maintain mineral balance by regulating the absorption of trace minerals at the intestinal level. This process involves the coordination of transport proteins, storage proteins, and regulatory hormones to ensure that the body absorbs only what it needs and prevents toxicity from excessive mineral intake.
iron: ferritin prevent excess absorption
zinc: metallothionein = a binding protein that blocks Zn’s excess movement into circulation. The ‘mucosal block’ is overridden with high doses of supplements.
What mineral is part of the mandatory fortification program in Australia? explain why?
mandatory salt iodisation
Thyroid Function: Iodine is an essential mineral required for the synthesis of thyroid hormones, which are crucial for regulating metabolism, growth, and development.
Preventing Iodine Deficiency Disorders: Adequate iodine intake is vital for preventing iodine deficiency disorders (IDDs), which include goiter (enlarged thyroid gland), hypothyroidism, and various developmental abnormalities in children, such as cretinism.
What are the trace minerals at risk in the context of chronic alcohol consumption? explain why and the consequences overtime.
Zn: functions in alcohol dehydrogenase, converts ethanol to acetaldehyde
will result in reduced HCl production and can lead to anorexia (loss of appetite)
increases renal excretions of manganese, iron, magnesium, selenium, copper
explain why selenium deficiency can result in iodine function deficiency
has a coenzyme cofactor role in iodothyronine 5’ deiodinases: three forms of enzyme, active in different sites, convert T4 to T3 by removing 1 Iodine
Type of iron found exclusively in animal products
heme iron
Type of iron found in both plant and animal products
Non-heme iron
Ferric iron is reduced to ferrous iron by HCl, ascorbic acid and _______ in the duodenal brush border
reductases
Ferrous iron is absorbed via
DMT1
DMT1 synthesis is influenced by _______
iron status
Heme iron is absorbed via
HCP1
Fe2+ is stored in enterocytes bound to _______
ferritin
Ferrous iron is transported across the basolateral membrane of enterocytes via _______
ferroportin
Membrane-bound copper-dependent enzyme that oxidises Fe2+ to Fe3+ for transport
hephaestin
Copper-dependent enzyme that oxidises Fe2+ to Fe3+ in the circulation
ceruloplasmin
Fe3+ is transported in the blood bound to _______
transferrin
Iron is taken up into body cells via _______
endocytosis
Heme-containing protein that transports oxygen in red blood cells
hemoglobin
Heme-containing protein that stores oxygen in muscle cells
myoglobin
Iron is a cofactor in lysyl and prolyl hydroxylase involved in _______ synthesis
collagen
Iron-dependent antioxidant enzyme that converts hydrogen peroxide to water and oxygen
catalase
Iron-dependent enzyme involved in the synthesis of thyroid hormones
Thyroid-peroxidase
Iron is a cofactor to phosphoenolpyruvate carboxykinase which is required for _______
gluconeogenesis
Iron-deficiency results in what kind of anaemia?
Microcytic hypochromic
Iron toxicity can result from a genetic disorder called _______ where regulation of intestinal iron absorption is impaired
Hemochromatosis
Factors increasing iron absorption
heme-iron
vitamin C
high demands for red blood cells
meat protein factor (MPF)
gastric acidity
low iron stores
Factors decreasing iron absorption
high iron stores
excessive intake of other minerals
polyphenols
antacids
phytic acid
oxalic acid
Zinc deficiency was first identified in high phytate diets in the Middle East, resulting in _______
Adolescent nutritional dwarfism
Major zinc transporter for absorption into enterocytes
ZIP4
In large doses (e.g. supplements) zinc is absorbed via _______
Paracellular diffusion
Protein that binds and stores zinc in enterocytes and body tissues
Metallothionein
Zinc is transported across the basolateral membrane of enterocytes via _______
ZnT1
Zinc is transported in the circulation bound to _______, α2-macroglobulin, or histidine or methionine
albumin
Zinc is needed for the conversion of retinol to retinal as a cofactor of _______
Alcohol dehydrogenase
Carboxypeptidases A and B are zinc-dependent enzymes involved in _______
protein digestion
Polyglutamate conjugase is a zinc-dependent enzyme involved in _______
Folate digestion
Zinc plays a _______ role in the antioxidant enzymes SOD1 and SOD3
Structural
Zinc deficiency leads to poor wound healing due to the role of zinc in _______
Matrix-metalloproteinases
Zinc fingers promote the binding of _______ to MREs in the promoter region of genes
Transcription factors
Zinc deficiency reduces the _______ response to carbohydrates
Insulin
Zinc deficiency results in reduced taste acuity due to its role in _______
An especially good source of zinc
oysters
Copper is found in food primarily in the ____ valence
2+
Copper is absorbed in the ____ valence
1+
Cupric copper is reduced to cuprous copper by HCl, _______ and reductases in the duodenal brush border
Vitamin C
Copper is mainly absorbed in the duodenum but some is absorbed in the _______
stomach
Citric, malic, gluconic and acetic acid _______ copper for absorption
chelate
Copper is stored in enterocytes bound to _______
Metallothionein
Copper is transported to the liver bound to _______ and α2-macroglobulin
albumin
Copper is released from the liver and transported in the circulation bound to _______
Ceruloplasmin
Copper is a cofactor in dopamine monooxygenase for the synthesis of _______
Norepinephrine
Copper is a cofactor of the antioxidant enzyme _______
Superoxide dismutase
Copper deficiency leads to iron-deficiency anaemia because copper is a cofactor in _______
Ceruloplasmin
Copper deficiency leads to hypopigmentation of hair and skin due to the role of copper in _______ enzymes
Tyrosinase
Copper is involved in crosslinking of collagen and elastin as a cofactor of _______
Lysyl oxidase
Manganese is found in the 2+ or ____ valence
3+
Manganese is absorbed along the small intestine via simple diffusion, _____ or ZIP14
DMT1
The presence of _______ facilitates manganese absorption
histidine
Manganese is transported from the liver to tissues bound to _______, α2-macroglobulin or other globulins
transferrin
25-40% of manganese in the body is found in _______
bone
Mn is a cofactor to glycosyl and xylosyl transferases in the synthesis of _______ in connective tissue
Glycosaminoglycans
Mn is a cofactor in arginase which cleaves arginine to form _______ and ornithine
urea
Mn is a cofactor in pyruvate carboxylase and PEP carboxykinase in _______
gluconeogenesis
Mn is a cofactor in the antioxidant enzyme _______
SOD2
Manganese toxicity known as _______ results in severe neurological manifestations
Manganism
Iodine content in food reflects regionally variable _______
soil content
Iodine is found in food as _______ or iodide
iodate
The absorption form of iodine
iodide
Iodide is absorbed in the stomach and duodenum by active transport via _______
Sodium-iodide symporter
Some foods contain _______ that interfere with iodine absorption or uptake into the thyroid gland
Goitrogens
The main function of iodine is as a component of _______
thyroid hormones
The most common thyroid hormone in the circulation
T4
The most biologically active thyroid hormone
T3
Iron-dependent enzyme that adds iodine to thyroglobulin
Thyroid peroxidase
Selenium-dependent enzymes that convert T4 to T3 in cells
DIO
T3 binds to nuclear receptors which bind to DNA to promote _______
gene expression
Thyroid hormone stimulates _______ expenditure
Basal energy
In adipose tissue, thyroid hormone enhances _______
Lipolysis
In the bone, thyroid hormone promotes _______
Anabolism
In terms of the cardiovascular system, thyroid hormone increases _______
heart rate
The RDI for iodine (150ug) can be met by consuming ____ teaspoon/s of iodised salt
1/2
Iodine deficiency results in _______ in adults
hypothyroidism
Enlargement of the thyroid gland to trap more iodine is known as _______
Goiter
When the mother is iodine deficient during pregnancy, this can lead to _______ in the infant
Neurological cretinism
_______ and dairy products are good sources of iodine
seafood
True or false: Australia has mandatory iodine fortification
true
The selenium content of food depends on _______ concentration
soil
Selenium is bound to _______ in plant foods
methionine
Selenium is bound to _______ in animal foods
Cysteine
Selenium is also found in lesser amounts as selenite and selenate in _______ foods
plant
Seafood is generally an excellent source of selenium, however the presence of _______ inhibits its absorption
Mercury
Selenium is transported to the _______ as free selenocysteine and selenomethionine
liver
Selenium is exported from the liver primarily as ______
Selenoprotein P
Selenium is stored in tissues as _______
Selenomethionine
Selenium is a component of 25 proteins and enzymes as _______
Selenocysteine
Selenium is a component of selenophosphate synthetase 2 needed for the synthesis of other _______
Selenoproteins
Selenoprotein that functions as an antioxidant enzyme
Glutathione peroxidase
Deiodinases are selenoproteins needed for the conversion of _______
T4 to T3
Selenium deficiency leads to reduced _______ activity
thyroid hormone
Chromium exists in food in the ____ valence
3+
The highest concentrations of chromium are in the liver, spleen and _______
bones
Chromium is released from food under _______ conditions
acidic
Chromium is mainly transported bound to _______ and albumin
tranferrin
While mechanisms are unclear, chromium seems to potentiate the action of _______
insulin
True or false: plasma and urinary chromium concentrations are good indicators of chromium status
false
Chromium deficiency leads to _______ resistance and elevated blood glucose and free fatty acids
insulin
At high doses, chromium leads to renal failure, liver dysfunction and _______ damage
DNA
Molybdenum is found in food as _______
molybdate
Molybdate is absorbed via _______ and via a carrier
passive difffusion
Molybdenum is transported bound to _______ or α2-macroglobulin
albumin
Molybdenum is a cofactor to four enzymes as _______
Molybdopterin
Molybdopterin is a cofactor in _______ which converts sulfite to sulfate
Sulfite oxidase
Molybdopterin is a cofactor in _______ which hydroxylates purines, pyrimidines and pteridines
Xanthine oxidoreductase
Molybdenum is involved in drug and toxin metabolism as a cofactor to _______
Amidoxime reductase
Molybdenum is involved in retinal and pyridoxal metabolism as a cofactor to _______
Aldehyde oxidase
Symptoms of gout have appeared in regions with high soil molybdenum content due to accumulation of _______ in joints
uric acid
