Trace & Ultra Trace Minerals Flashcards
What are the main functions of trace and ultratrace minerals?
catalytic center of enzymes; oxidation/reduction reactions; oxygen transport; structure
What are the main factors influencing absorption of iron?
metabolic need, nature of dietary iron, vitamin C, and meat factor
When iron status is adequate, how much of dietary iron is absorbed?
14-18%
When iron need is high, how much of dietary iron is absorbed?
35-40%
What are the two different types of dietary iron?
heme (hemoglobin, myoglobin) and nonheme (ferrous and ferric)
Where is heme iron found?
in animal meat
Where is nonheme iron found?
in plant based foods
Which is better absorbed, heme or nonheme iron?
heme iron
Which is better absorbed, ferrous or ferric?
ferrous
How does vitamin C affect iron absorption?
keeps the iron in the ferrous state which will increase absorption
How is iron absorbed?
through the brush border membrane into the small intestine by carrier-mediated mechanisms
What is the key iron-binding protein?
ferritin
What does the mucosal block do?
binds and stores mucosal iron preventing it from entering the bloodstream
What transports iron into the interstitial fluid for release into the bloodstream?
ferroportin
What copper containing enzyme oxidizes iron from ferrous to ferric form?
ceruloplasmin
Where is iron stored?
in the liver, bone marrow and spleen
T/F: there is a limited ability to excrete iron
true
What is hepcidin?
a protein that regulates iron balance
What are the functions of iron?
oxygen transport, apart of the mitochondria, and a cofactor for other enzymes
What is hemoglobin?
red blood cells
What does hemoglobin do?
carries oxygen in the blood from lungs to all tissues in the body and carbon dioxide back to the lungs for expiration
how many iron-containing heme compounds does hemoglobin have?
4
What does erythropoietin do?
stimulates bond marrow to produce more red blood cells where O2 capacity declines
What does myoglobin do?
transports oxygen from red blood cells to skeleton and heart muscle cells
What happens if you have iron deficiency?
microcytic, hypochromic anemia
What happens during the first stage of microcytic, hypochromic anemia?
storage iron depletion (decrease serum ferritin indicates lower stores)
What happens during the second stage of microcytic, hypochromic anemia?
transport iron depletion (decrease serum iron and increased transferrin)
What happens during the third stage of microcytic, hypochromic anemia?
Hemoglobin production decreases (increased free erythrocyte protoporhyrin; decreased blood hemoglobin; and decreased hematocrit)
What is hematocrit?
percentage of total blood volume comprised of red blood cells
What is protoporphyrin?
immature RBC
What is the RDA for iron?
8 mg/day for men and 18 mg/day for women
What is the UL for iron?
45 mg/day
What are sources of iron?
liver, eggs, lean meat, legumes, fruits, nuts, enriched grains
What is the richest source of iron?
meats and seafood
What happens if you have iron overload?
hemochromatosis
What is hemochromatosis?
genetic condition that is a deficiency of hepcidin that prevents degradation of transport protein ferroportin causing an excess iron absorption
What is a possible treatment?
phlebotomy (donating blood often)
What is the function of iodine?
an essential part of thyroid hormones
What are the two thyroid hormones?
thyroxine (T4) and triiodothyronine (T3) which is the active form
What do thyroid hormones do?
regulate growth, development, metabolic rate, and reproductive function
how is iodine absorbed?
in ionic form and carried to the thyroid gland
Where is iodine stored?
stored on thyroglobulin