Lecture 8 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)
thyroxine
hormone made by thyroid gland
- regulation of basal metabolic rate
iodine deficiency symptoms
- enlarged thyroid (goiter)
- sluggishness
- weight gain
- severe deficiency during pregnancy can cause congenital hypothyroidism
goiter
enlarged thyroid to trap iodine
congenital 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
1. absorption increases with diminished body supply and with need
2. absorption decreases when iron is abundant
ferritin
an iron storage where protein stores iron in the 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 people
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
- small intestine 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 over load
hemochromatosis
an inherited disease in which the body absorbed too much iron
- genetic component to iron overload
what population is hemochromatosis most common amongst?
caucasian men
hemochromatosis process
intestine continues to absorb iron at high rate despite the excess iron building up in the body tissues
early symptoms of hemochromatosis
- fatigue
- mental depression
- abdominal pains
later symptoms of hemochromatosis
- tissue damage
- liver failure
- abnormal heart beats
- diabetes type II
- likely infections because bacteria thrive on iron-rich blood
high-level iron fortification of foods
- pose no risk for healthy people
- many canadians take vitamin C supplements, which enhances iron absorption
iron supplements
- can reverse iron-deficiency anemia from dietary causes
- leading cause of fatal accidental poisonings among Canadian children under 6 years old
adult men and iron
rarely experience iron-deficiency anemia
vegetarians and iron
advised to obtain 1.8 times RDA
- iron in plant foods not well-absorbed
- diets lack factors from meat that enhance iron absorption
food vs supplement (iron)
- food is best source = better absorption
- pregnant women need an iron supplement
2 forms of iron in foods
- heme iron
- non-heme iron
heme iron
iron-containing part of hemoglobin and myoglobin found in meat, poultry and fish (bound to heme)
non-heme iron
found in foods from plants and meat, poultry and fish
is heme iron of non-heme iron absorbed better?
heme iron
MFP factor
- found in meat, fish, poultry
- promotes absorption of non-heme iron from other foods sources eaten at the same time
vitamin C and iron
can help absorption of iron from foods eaten in the same meal
impairment of iron absorption
- tannins
- calcium and phosphorus (milk)
- phylates
tannins
found in tea and coffee
- black tea is exceptional in its efficiency in reducing iron absorption (advisable for iron over load)
phylates
found in fibre of lightly processes legumes and whole-grain cereals
sources of iron
- red meats, fish, poultry, shellfish, eggs
- legumes, green leafy veggies, dried fruit
- cooking in iron pan adds iron
zinc
small quantity in human body
zinc functions
- works with proteins in every body organ
- helps more than 300 enzymes
- assists in immune function
- regulation of gene expression in protein synthesis
- taste perception
- wound healing
- sperm production
- fetal development
- growth and development in children
10.affects behaviour and learning - produces active form of Vitamin A in visual pigments
12.
what functions does zinc help 300 enzymes do?
- make parts of cell’s genetic material
- make heme in hemoglobin
- assist the pancreas with digestive functions
- help metabolize carbs, proteins, fat
- liberate vitamin A from storage in the liver
zinc deficiency symptoms
- adverse growth
- alters digestive functions and causes diarrhea (worsen malnutrition)
- impairs immune response (more infections - worsen malnutrition)
- poor wound healing
- abnormal taste
- abnormal vision in the dark
what is zinc deficiency often misdiagnosed as?
general malnutrition and sickness because symptoms are so vast
pancreatic juices and zinc
pancreatic juices are rich in zinc, so after a meal, the body gets zinc from the food and pancreatic enzymes
where is zinc primarily lost?
in the feces
zinc toxicity
- can cause serious illness or death (supplements only)
- may reduce blood conc of HDL
- can inhibit copper absorption and lower bodys copper content
- inhibit iron absorption
zinc absorption
- varies from 15-40%
- absorption decreases with increased intake
- absorption limited by phytates
food sources of zinc
- meats
- shellfish
- poultry
- milk and milk products
plant sources of zinc
no absorbed as well as animal sources
1. some legumes
2. whole grains
selenium functions
- works as an antioxidant (prevents oxidative harm)
- activates thyroid hormone
- similar to sulfur and can occur in place of sulfur in amino acids
what can selenium deficiency lead to?
- cancer
- heart disease
cancer due to selenium deficiency
low blood selenium correlated with them development of some forms of cancer (prostate)
heart disease due to selenium deficiency
associated with keshan disease
keshan disease
heart enlargement and insufficiency
- selenium deficiency may predispose people to the disease
- adequate selenium seems to prevent keshan disease
selenium toxicity
long-term supplementation
selenium toxicity symptoms
- nausea
- abnormal pain
- hair loss
- nerve abnormalities
selenium sources
- meats
- shellfish
- veggies and grains grown in selenium-rich soils
selenium supplements
no benefits seen from selenium supplements unless selenium deficient
fluoride
not essential to life but if beneficial
fluoride functions
- crystalline deposits in bone and teeth
- forms more decay-resistent fluorapatite in developing teeth
sources of fluoride
- primary = fluoride drinking water
- tea and seafood
fluoride deficiency
where fluoride is missing the incidence of dental decay is high
fluridation
practical, safe and cost-effective way to help prevent dental caries in the young
fluoride toxicity
fluorosis - discolouration and pitting of tooth enamel caused by excess fluoride during tooth development (irreversible)
chromium function
works closely with insulin to regulate and release energy from glucose
chromium deficiency
- impaired insulin action
- results in diabetes-like conditions of high BP
- resolves chromium supplementation
chromium supplements
cannot cure common forms of diabetes
sources of chromium
- unrefined foods and whole grains (lost during processing)
- liver
- whole grains
- nuts and cheeses
copper function
- formation of hemoglobin and collagen
- many enzymes depend on copper for its oxygen-handing ability
- role in handling of iron
- assists in reactions leading to release of energy
- copper-dependent enzyme (superoxide dismutase) helps contorl damage from free-radical activity in the tissues
copper deficiency
- rare
- can be caused by excess zinc
- menkes disease
menkes disease
intestinal cells absorb copper but can’t release it into circulation causing deficiency
symptoms of menkes disease
- can severely disturb growth and metabolism
- can impair immunity an blood flow through arteries
copper toxicity
- unlikely from foods
- can be caused by supplementation
- wilsons disease
wilsons disease
copper accumulates in the liver and the brain
copper sources
- organ meats
- seafood
- nuts and seeds
- whole grains
- water may supple copper (especially with copper plumbing pipes)
- in canada, copper intakes are adequate
other trace minerals
- molybdenum
- manganese
- boron
- cobalt
- nickel
- silicon
- arsenic
molybdenum
functions as a part of several metal-containing enzyme
manganese
works with enzymes
boron
influences activity of many enzymes
cobalt
mineral in vitamin B12
- other name for vitamin B12 is cobalamin
nickel
important for the health of many body tissues
nickel deficiency
harm to the liver and other organs
silicon
bone calcification in animals
arsenic
- a known poison and carcinogen
- may turn out to be essential in small quantities
trace minerals toxicity
- all trace minerals can be toxic in excess
- overdoses are most likely to occur in those who take supplements
