Trace Elements Flashcards
Is RDA for iron in women between 19-50 taking oral contraceptives lower or higher
Lower
Is the RDA for iron in women 51+ higher or lower
Lower
what food products are good sources of iron?
meat and fish, leafy greens, lentils and whole grains
- cooking with iron utensils adds iron to food
why do vegetarians/vegans require more dietary iron?
because the iron in plant foods is more difficult to absorb
iron that is part of which group is better absorbed?
heme-group
what food is heme-iron found in?
meat (hemoglobin in blood and myoglobin in muscle)
what is non-heme iron?
any dietary iron that is not bound to the heme group (e.g. plant-based iron).
- This is more difficult to absorb
iron is absorbed in which form?
directly in its Fe2+ (ferrous) form or as Heme-bound iron
- easier to absorb
what can enhance the absorption of iron?
Acidic foods, stomach acid and Vitamin C
what can prevent absorption of iron?
Fibre, phytates, tannins and oxalates can bind iron and prevent its absorption
- as well as other minerals (calcium)
how is iron stored?
stored as part of the protein Ferritin in:
- Mucosal Cells
- Liver
how is iron transported?
transported as part of the protein Transferrin
- Body cells for use like myoglobin
- Bone marrow for production of RBCs
- RBCs as hemoglobin for transport of O2
- Liver for storage as Ferritin
- RBCs are recycled in the spleen, marrow and liver, allowing the iron to be reused
when can iron be lost?
- When mucosal cells containing ferritin die
- When blood is lost, results in loss of transferrin and hemoglobin in RBCs
what is iron used for in the body?
- Hemoglobin – delivery of O2 and removal of CO2
- Myoglobin – storage of O2 in muscle cells
- Citric Acid Cycle and Electron Transport Chain Proteins
- Drug Metabolism – Cytochrome P450 (contains a Heme group)
- Immune Function
- Catalase – Protein that protects from oxidative stress by converting H2O2to water and oxygen
does iron deficiency happen fast or slow?
slow
what are common symptoms of iron deficiency?
fatigue, weakness, headache, decreased work capacity, an inability to maintain body temperature in a cold environment, changes in behavior, decreased resistance to infection, adverse pregnancy outcomes, impaired development in infants, and an increased risk of lead poisoning in young children, [pica]
what’s the normal range for hematocrit for men and women?
men: 0.420-0.520
women: 0.370-0.460
what’s the normal range for hemoglobin for men and women?
men: 140g/L
women: 123-157 g/L
what’s the normal range for serum iron?
11-32 umol/L
what’s the normal range for ferritin?
10-250 ug/L
iron toxicity leads to what?
increased oxidative stress
what is one of the most common forms of poisoning children?
iron toxicity - ACUTE
what is chronic iron toxicity?
Iron Overload or hemochromatosis
- Increased iron absorption
what are forms of iron supplementation?
- Iron cookware and utensils
- Iron consumed with acidic foods and foods with vitamin C (e.g. orange juice) is more readily absorbed
why should dairy consumption be avoided when aiming to increase iron intake?
calcium, Ca2+ can interfere with absorption
Iron supplements can interfere with intake of which trace elements?
Copper and Zinc
zinc from what sources is better absorbed?
meat
what can prevent the absorption of zinc?
Phytates in vegetables can bind zinc and prevent its absorption
what is zinc lost in?
lost in grain processing and not added back as enrichment
what do Zinc transport proteins regulate?
the amount of zinc absorbed in the small intestine
what does Metallothionein proteins regulate?
the amount of zinc that moves into the blood from the mucosal cells
how is zinc excreted?
in the pancreatic and intestinal juices, allowing excess zinc to be removed from the body
copper absorption is highly impacted by which trace element?
zinc
high zinc = low copper
what food products are good sources of copper?
Organ meats, seafood, nuts and seeds, whole grains
- Soil content will impact levels in food
Free copper can lead to what?
oxidative damage, so transported in the blood with albumin
where is copper secreted?
in the bile, allowing it to be excreted in the feces
copper is important in the transport of which element?
iron
what can prevent oxidative stress with copper?
Superoxide dismutase
Deficiency is rare in copper but symptoms include:
- anemia (poor iron transport) and
- connective tissue defects (similar to scurvy due to its role in collagen cross-linking)
what food products are the best sources of manganese?
whole grains and nuts
how is manganese eliminated?
in bile
Manganese-requiring enzymes are involved in what?
amino acid, carbohydrate, and cholesterol metabolism, cartilage formation, urea synthesis, and antioxidant protection
manganese is a part of mitochondrial superoxide dismutase. t or f
t
what food products are good sources of selenium?
Seafood, animal products, and whole grains (depending on soil content)
is absorption regulated in selenium?
no, excess selenium is excreted in the urine
selenium is a part of selenoproteins (proteins with selenium). t or f
t
Glutathione peroxidase is an example
Protects from oxidative stress by neutralizing peroxides
selenium is needed for the synthesis of which hormone?
thyroid hormones
what does a deficiency in selenium look like?
- Muscular discomfort and weakness
- Keshen disease
Enlarged heart and poor heart function
what does selenium toxicity look like?
Changes in fingernail structure and hair loss
where is iodine found in?
sea water
is the RDA for iodine high or low during pregnancy and lactation?
higher
what food products are a good source of iodine?
- Seafood and plants grown near the sea would be high in iodine
- Plants grown far from the sea have low iodine in their soil
- Can also make it into our food from additives in cattle feed and disinfectants that contain iodine
Salt sold for household use must be fortified with what?
iodine (iodized salt)
iodine is used in the synthesis of what hormone?
thyroid hormone
- Thyroid hormones are synthesized from the amino acid tyrosine
where is fluoride present?
in low amount in almost all soil, water, plants and animals
what food product is a good source of fluoride?
tea
In the body, fluoride associates with calcium and helps protect what?
protect teeth from cavities by making the enamel more resistant to acids
deficiency in fluoride can increase the risk of what?
tooth decay
high doses of fluoride can lead to what?
fluorosis
When do symptoms occur from iron deficiency?
When it reaches iron deficiency anemia
Tx for iron toxicity
Replacing blood, or removing blood from the body
The more zinc you consume, doesn’t mean it’s gonna get into the blood. T or F
T
Zinc is a cofactors for over 300 enzymes, and helps reduce
Oxidative stress as a cofactor in superoxide dismutase
Zinc in DNA binding proteins
Many hormones bind to proteins w zinc fingers, meaning deficiency can have widespread effects on the body
Zinc deficiency usually occurs in those with
A mutation in a zinc transporter
Those consuming diets low in protein or high in phytates
Cause of copper toxicity
due to contaminated water supplies or water/food stored in copper
How is absorption inversely associated with intake of manganese
More you intake, less you absorb
Is the RDA for iodine in pregnancy and lactation higher or lower
Higher
Iodine can make it into our food from additives in
Cattle feed an disinfectants that contain iodine
Synthesis of thyroid hormone from iodine regulate gene expression of proteins involved in:
Protein synthesis
Basal metabolic rate
Growth and development
Thyroid stimulated hormone (TSH) in Iodine
Released when hormone levels drop
Causes thyroid hormone to synthesis more, enlarging it and taking it more iodine
What leads to enlargement of the thyroid gland with iodine deficiency
Iodine deficiency means no thyroid hormones are being made and TSH keeps getting released , leading to enlargement of the thyroid gland
Iodine deficiency leads to the development of
Goiter
Iodine hormones are needed for growth and development in
Pregnancy and lactation
What can happen if iodine is deficient in pregnancy and lactation
Still birth, abortion, cretinism in children
What are goitrogens
Substances in food that limits iodine bioavailability (cabbage, cassava, millet)
