week 12 Flashcards
minerals
inorganic elements that retain their chemical identity (not destroyed by cooking or storing)
the trace minerals
iodine
iron
zinc
sulphur
selenium
fluoride
chromium
copper
iodine function
- integral part of thyroxine (hormone)
thryoxine
hormone made by thyroid gland
- regulation of basal metabolic rate
iodine deficiency symptoms
- enlarged thyroid (goiter)
- sluggishness
- weight gain
- sever def during pregnancy can cause congenital hypothyroidism
goiter
enlarged thyroid to trap iodine
congential hypothyroidism
extreme irreversible mental and physical developmental delay
most preventable causes of intellectual delay
what foods cause iodine deficiency?
collards, kate and brussel sprouts
- contain goitrogens which inhibit iodine uptake by thyroid
iodine toxicity
enlarged thyroid glant
can be deadly in very large amounts
sources of iodine
seafood (from ocean)
iodized salt
amount varies with amount in soil in which plants are grown or on which animals graze
iodized salt
less than 1/2 tsp meets an entire days recommendation
sea salt and iodine
sea salt contains very little iodine
- dry all of it out and iodine is blown away
iron
essential nutrient and deficiency is problem for many
what contains most of the body’s iron?
hemoglobin and myoglobin
hemoglobin
oxygen-carrying protein of red blood cells
myoglobin
oxygen-holding protein of muscles
iron function
carried oxygen
helps many enzymes use oxygen
needed to make new cells, amino acids, hormones and , neurotransmitters
iron storage and excretion
liver puts iron into red blood cells sent from bone marrow
RBCs die after 3-4 months and the liver and spleen break them down and recycle their iron
how is iron balance maintained?
through absorption
iron loss
small amounts of iron is loss in nail clippings, hair cutting, shed skin cells
loss of iron from bleeding can be significant
obtaining iron
only approx. 10-15% of iron is absorbed
- absorption increases with diminished body supply and with need
- absorption decreases when iron is abundant
ferritin
an iron storage where protein stores iron int he mucosal cells of small intestine
what happens when iron is needed
iron is released to transferrin and travels through blood to body
what happens when iron is not needed?
iron is shed with the intestinal cells which are replaced every 3-5 days
free iron
powerful oxidant
- can start free-radical reactions that damages cells
iron deficiency
result of iron absorption not compensating for losses or low dietary intakes
decreased iron stores
stage I iron deficiency
depleted iron stores
stage II iron deficiency
iron deficiency anemia
depletion of iron stores resulting in low blood hemoglobin (stage 3 deficiency)
- people can be iron deficient without being anemic
anemia results
cells contain too little hemoglobin and thus deliver too little oxygen which limits cells metabolism
symptoms of anemia
tiredness
apathy
a tendency to feel cold
what are symptoms of an iron deficiency often mistaken for
behavioural or emotional problems
pica
craving non-food substances
- occurs with iron deficiency sometimes
- inhibit iron absorption and displace food substances
causes of iron deficiency and anemia
malnutrition and inadequate iron intake
lack of food
high consumption of wrong foods
non-nutritional causes of anemia
losses or increased need
1. blood loss - 80% of iron is stored in blood
2. GI bleed
2. women in reproductive years
what populations need increased iron to support growth of new tissue
infants over 6 months
children and adolescents
pregnant women
what is the most common nutrient deficiency?
iron (1.2 billion)
iron toxicity
toxic in large amounts
difficult to excrete once absorbed
iron overload
hemochromatosis
how does the body defend against iron overload?
controlling its entry (hepcidin)
hepcidin
a hormone secreted by liver that limits iron absorption
controlling entry of iron
- SI traps some iron and holds it within boundaries (mucosal cells)
- when mucosal cells are shed, excess iron they collected is lost from the body
- when iron stores are filled, less iron is absorbed - protects from iron overload
hemochromatosis
an inherited disease in which the body absorbed too much iron
- genetic component to iron overload