Exam 3 - chantel1 Flashcards
What are trace elements? Major concern?
Elements required in trace amounts
>Rate of bioavailability
What are some trace elements?
iron, zinc, copper, iodine, fluoride, chromium, selenium
Where is iron found?
[Fxn?]
Hemoglobin! (in the blood)
[Cellular metabolism]
What are the different types of iron? What affects absorption?
*HEME iron—-found in ANIMAL products, READILY ABSBD form, chemically associated w/ proteins such as hemoglobin and myoglobin
*NON-HEME iron—found in both PLANT and animal foods, POORLY ABSBD form, NOT part of iron complex found in hemoglobin and myoglobin
>VIT C can enhance abspt up to 6x.
>Fiber, phytates, tannins, and oxalates interfere w/ abspt
What is iron deficiency anemia? Symptoms?
Hemoglobin can’t be produced w/ insufficient iron
>RBCs are microcytic and hypochromic—small, pale
>Unable to deliver sufficient O2 to the tissues
> Symptoms related to low blood O2: fatigue, weakness, headache, decreased work capacity, an inability to maintain body temp in cold environment, changes in behavior, and impaired development in infants.
Who Is at Risk for Iron Deficiency?
Women (menstruation), infants/children/ adolescents, and athletes are at higher risk due to increased need and/or poorer food choices
When can iron toxicity occur? How?
UL = 45 mg/day —Impossible to reach by food, possible by supplements
What happens if too much iron is ingested? Effects of iron overload over time?
Life-threatening
>Can damage intestinal lining
>Abnormalities in body pH, shock, and liver failure
Over time, iron
>Accumulates in tissues such as heart and liver
>Contributes to type 2 DM, heart disease, and cancer
*Can only lose iron through losing blood
How does body defend against excess iron?
Mucosal block in intestinal cells offers protection
>Body regulates how much iron is absbed
>If deficient, absb more; otherwise, absb less
To protect against toxic effects of iron, body regulates amount that enters blood from mucosal cells of gastrointestinal tract. This is called a “mucosal block”.
Why is Zinc needed?
> Essential for growth and development
Mainly involved in enzymes–USED IN OVER 300 diff enzymes
»e.g. antioxidant enzyme “superoxide dismutase,” which is vital for protecting cells from free radical damage
What are the different sources of Zinc?
Animal sources– Better absorbed
Plant sources— often bound by phytates
*Zinc is abundant in red meat, liver, eggs, dairy, veggies, some seafood
(Most abundant intracellular trace element)
What is hemochromatosis? Treatment?
genetic disorder in which too much iron is absorbed (excess iron accumulates)
>Mainly afflicts men of white European descent
Treatment: bloodlet (take blood out of them)
Effects of excess Zinc? How do we protect ourselves?
> hair loss
can be toxic!
**decreases bioavailabilty of Cu– can cause copper deficiency, leading to anemia
Protect ourselves by losing zinc when mucosal cell dies
Effects of Zinc deficiency?
> poor growth,
delayed sexual maturation,
skeletal abnormalities,
decreased immunity
Why do we need copper? (Sources?)
Prevents certain types of anemia–transports iron to hemoglobin
(role in connective tissue synthesis)
(Organ meat, seafood, nuts, seeds)
Why is selenium important?
Selenium is an impt part of body’s antioxidant defenses
How can we obtain selenium?
depends on selenium content of soil (plant products) or in animal feed (animal products)– grains, seeds (sunfower, pumpkin) seafood, eggs, and organ meats
What enzyme is selenium important in?
??????
“Part of enzyme glutathione peroxidase – neutralized oxidation products”
*Glutathione peroxidase—-protects against oxidative damage as an essential part of this enzyme
>Thus reduces need for Vit E
>Ppl shouldn’t be on both selenium and Vit E supplements
»>Selen suplmnt related to (colon, prostate) cancer
»>Vit E suplmnt found to increase oxidization
What is selenium deficiency?
Keshan disease
>Heart mscl is oxidized
>Symptoms include muscular discomfort and weakness
What does iodine content of food depend on?
the soil!
>soil near ocean or sea is higher than inland
>Iodine is naturally found in sea
What foods contain iodine?
Seafood, sea salt (duh)!
Iodized salt–supplies most of iodine!
How is iodine used in the body?
Mostly found in thyroid gland (>50% body iodine)
>Essential component of thyroid hormones, including thyroxine!
>thyroid hormones control metabolism
»>hyperthyroidism– hard to keep weight on, fast metabolism
»>hypo– hard to keep weight off, slow
Toxicity and Iodine?
Possible! Excess seaweed consumption!
Iodine deficiency is characterized by?
GOITER—enlarged thyroid gland
>caused by continued release of thyroid stimulated hormone Cretinism
>if pregnant, causes “Cretin”–retarded child w/ goiter
What are goitrogens?
found in cabbage, cassava, millet–limit bioavability of iodine
What is chromium found in?
> Brewer’s yeast, liver, nuts, and whole grains
>Cooking in stainless steel can increase food’s chromium content
What does chromium do? Why needed?
Involved in carb and lipid metabolism
>Needed for normal insulin action and glucose utilization
(Does not help w/ weight loss–chromium picolainate)
What does fluoride do?
Promotes dental health (decreases cavities, or tooth decay)
Where can we get fluoride from?
> Fluoridated water,
Tea,
Marine fish eaten w/ their bones (such as canned salmon or sardines)
Topical toothpaste
»BUT present in small amounts in almost all soil, water, plants, and animals
How is iron absbd? Lost?
absorbed into the absbd into intestinal mucosal cells and “mucosal block” controls abspt into body
1-2mg of normal iron loss/day due to RBC turnover (despite minimal recycling)
>More iron is lost in body when stores are high than when they’re low (??)
What two protein help w/ iron storage and transport? How is Fe excess stored?
Ferritin (storage) and tranerrin (transport)
>Excess iron is stored in liver primarily bound to ferritin
How is iron homeostasis regulated?
regulated at intestine w/ peptide hormone hepcidin (released by liver) serving as primary regulator
What happens when Fe stores are low?
more iron is transferred from mucosal cells to blood and bound to transferring for transport to body cells
What happens when Fe stores are high?
less iron is transported from mucosa into blood and more is bound to ferritin and lost when mucosal cells die
