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
