Chapter 13 The Trace Minerals
Terms in this set (99)
halts activation of thyroid hormone, which requires iodine.
Role of Iron in the body
- a Cofactor in oxidation-reduction reactions that make amino acids such as collagen, hormones, and neurotransmitters.
- Also part of electron carriers in electron transport chain.
- Hemoglobin and myoglobin in blood, muscles carry, accept and release oxygen.
2 types of Iron
Ferrous iron (Fe2+)
Ferric Iron (Fe3+)
The body conserves ___ and excretion is difficult. So balanced is maintained primarily though ____ _____
- regulating absorption
Special proteins help body absorb from food:
captures iron from food and stores it in small intestine
an iron transport protein picks up iron from ferritin when the body needs it
When none is needed, what happened to iron?
it is excreted with intestinal cells (every 3-5 days)
percentage of Iron in meat, fish, and poultry is bound into heme?
Nonheme iron percentage?
account for about 10% of the average daily iron intake, but it well absorbed (about 25%)
accounts for the remaining 90% but it is less well absorbed (about 17%)
All iron derived from plant foods is??
Absorption of noontime iron is prohibited by?
Phytates in legumes, grains, and rice
Vegetable proteins in soy, legumes nuts
Calcium in milk
individual variation in absorption due to health, stage in life cycle, and iron status?
Transport of Iron
Transferrin delivers iron to bone marrow to make new red blood cells and to other tissues in smaller amounts.
Storage of Iron
Ferritin, bone marrow, spleen.
When concentrations are too high, liver converts some into Hemosiderin, which releases iron more slowly.
This protects the body from free radical damage.
RBC usually live how long?
4 months before dying and degraded by the spleen and liver.
The hormone Hepcidin
limits iron absorption in intestine and release from liver, spleen, bone marrow to maintain balance.
1. Live and spleen
dismantles RBC, packages iron into transferrin, and stores excess iron in ferritin (and hemosiderin).
2. Some losses via sweat, skin, urine. OR Transferrin
carries iron in blood
3. Some iron delivered to myoglobin of muscle cells OR Bone marrow
incorporates iron into hemoglobin of RBC and stores excess iron in ferritin (and hemosiderin)
4. Iron-containing hemoglobin in RBC carried
5. Some losses if bleeding occurs OR
back to liver and spleen dismantles RED and packages iron into transferrin.
The most common nutrient deficiency worldwide?
increases iron risks.
vulnerable stages in life
women in reproductive years, pregnancy.
infants and young children
blood losses - trauma or small chronic losses like with elders, parasites, or malaria
assessment of deficiency
developers in stages
iron deficiency developed in stages:
iron stores diminish
iron deficiency developed in stages:
Decrease in transport iron
iron deficiency developed in stages:
hemoglobin and hematocrit values as erythrocyte protoporphyrin (RBC precursor) accumulates
iron deficiency and anemia are not the same thing. Deficiency of iron
depleted iron stores without regard to degree of depletion
severe depletion of iron stores. low hemoglobin concentrations
results in pale, small RBC (hypochromic and microcytic)
energy and iron deficiency
energy metabolism is impaired, neurotransmitter synthesis is altered.
- reduces work capacity and mental productivity, motivation, energy
- headaches, pallor, poor cold resistance
- you only get tired when you are doing something, not like sleepiness
part of iron deficiency. craving and consumption of nonfood substances like dirt. Ice is common.
hereditary hemochromatosis: the most common genetic disorder in the US.
failure to prevent unneeded iron from being absorbed, results in HEMOSIDEROSIS.
signs and symptoms similar to iron deficiency, so self diagnosing deficiency = bad.
- GI distress, rapid heartbeat, weak pulse, dizziness, shock, confusion.
- UL is 45 mg/day for adults
- 40mg/day kids
RDA's iron for men and women
8mg/day for men
18mg/day for women
vegetarians needs 1.8X as much
choose soy foods, legumes, seeds, dried fruit, blackstrap molasses.
Vitamin C does not hep which mineral?
Roles in body: cofactor for over 100 enzymes
growth & development
synthesis, storage, and release of insulin
thyroid hormone function
behavior and learning performance
- participates in metabolic functions of mucosal intentional cells, or is retained by METALLOTHIONEIN until the body needs it.
- some incorporated into pancreatic enzymes.
- small intestine receives two doses of zinc. one from food, one from enzymes.
dietary factors of zinc
absorption decreases as intake increases, 15-49%.
enteropancreatic circulation definition
Pancreas -> small intestine -> pancreas
transported in the blood by ALBUMIN and TRANSFERRIN
may be reabsorbed or shed in intestinal cells each time.
some also lost in bodily fluids, skin
enteropancreatic circulation of zinc: 1
Metallothionein releases zinc to albumin and transferrin for transport to the rest of the body.
enteropancreatic circulation of zinc: 2
The pancreas uses zinc to make digestive enzymes and secretes them into the intestine.
enteropancreatic circulation of zinc: 3
Mucosal cells in the intestine store excess zinc in metallothionein.
enteropancreatic circulation of zinc: 4
Zinc is not absorbed
and is excreted in shed intestinal cells instead. Thus, zinc absorption is reduced when the body does not need zinc.
1/20 childhood deaths in developing world, common with middle eastern diet.
symptoms and outcomes of zinc deficiency
- growth retardation, immature sexual development.
- impaired immune response, wound healing
- damage to CNS - poor motor development, cognition
- altered taste, loss of appetite.
>50mg may cause GI problems, headache, exhaustion.
0 interference with copper metabolism leads to degeneration of cardiac muscle
sources of zinc
- shellfish, meats, poultry, dairy.
- enough in vegetables and grains if you eat a lot.
RDA of zinc
supplementation treats of zinc
many childhood infections, may treat colds.
GI tract converts iodine to iodide
Iodine in food becomes iodide in the body
The hypothalamus regulates thyroid hormone productions by
controlling the pituitary gland's release of TSH (thyroid stimulating hormone)
this regulates body temperature, metabolic rate, reproduction, growth, blood cell production, nerve and muscle function, etc.
thyroid hormone is not produced, but more and more TSH is released.
thyroid cells expand
Iodine causes preventable
mental retardation and brain damage (which can be treated)
by deficiency during pregnancy, extreme and irreversible
interferes with thyroid function
- enlarges thyroid gland
goiter in an infant
can cause block breathing
recommendations of iodine
sources of iodine
salt, dough conditioners, processed foods, seafood, soils near oceans.
substitute for sulfur in some amino acids
- methionine, cysteine, and cystine
selenium roles in the body
antioxidant : prevents free radical formation
- parts of proteins = activation/inactivation of thyroid hormone
kasha disease, a heart disease in regions of China where soils lack selenium.
may protect against some cancers
loss of hair and nails, garlic breath, nervous system problems. UL 400 ug/day
sources of selenium
found in soil
meats, milk, and eggs
brazil nuts (2/day)
recommendations of selenium
RDA 55 ug/day
based on glutathione peroxides activity
transport and balance depend on a system of proteins
roles of copper in the body
constituent of enzymes
reactions that consume oxygen or oxygen radicals
is rare in the US, in animals cause cardiovascular disease
excessive intakes unlike from foods, may cause liver damage from supplements
copper: menkes disease
intentional cells absorb but cannot release copper. treat with IV copper
copper: wilson's disease
accumulates in liver, brain. treat with chelation and zinc
sources of copper
legumes, whole grains, nuts, shellfish, seeds
- more than half of copper from foods is absorbed
route of elimination is bile
20mg in the whole body
bones and metabolically active organs (liver, kidneys, pancreas)
manganese role in the body
cofactor for enzymes that facilitate metabolism (pyruvate conversion, breaking up carbs, fats, amino acids)
rare but requirements are low. 1.8-2.3 mg/day
phytates, high iron/calcium intake =
limit manganese absorption
toxicity of manganese
usually as environmental contamination, not diet (miners)
brain disease, off behavior and appearance
grain products the main source
found in bones and teeth
prevents dental decay
Fluorapatite - fluoride
replaces hydroxyl group in hydroxyapatite crystals
sources of fluoride
fluoridated drinking water at 1ppm provides 1 mg/day
tea and fish
causes FLUOROSIS which is white flecks, pitting on teeth, at 10mg/day.
Irreversible, so don't let your kids eat their toothpaste.
participates in carbohydrate and lipid metabolism
helps maintain glucose homeostasis by enhancing insulin activity
diabetes - like condition may develop without ___. High glucose in blood, low insulin/glucagon response
sources of chromium
unrefined foods like yeast, grains, liver.
refined foods lack this
supplements for chromium
supplements for building muscles: who knows.
working part of several metalloenzymes
dietary deficiencies are unknown because so little is needed
0.1ppm in body
sources of Molybdenum
legumes, breads, grain products, leafy green vegetables, milk, and liver
toxicity of Molybdenum
is rare. can cause kidney damage and reproductive abnormalities
Molybdenum UL and RDA
RDA = 45 uh/day
heavy metals that impair body's growth, work capacity, and general health.
contaminant minerals: lead
common due to paint in old houses.
displaces other minerals (replaces iron in heme, but can't carry oxygen)
contaminant minerals: mercury
cadmium similar but less common.
enter food though pollution in soil, air, water.