Trace Minerals Flashcards
What are the macronutrients? Why are they essential?
Carbohydrates, proteins, lipids.
Essential because they supply energy for cells whereas micronutrients don’t.
What are minerals?
Essential, inorganic elements required in maintaining the normal functions of our body. They are important for bone health, growth and development, bone formation and clotting and nerve impulses. They are also important as electrolytes and as antioxidants.
What are MAJOR minerals? Define and name.
Minerals required > 100 mg per day. Calcium Phosphorous Potassium Sulfur Sodium Chloride Magnesium
Factors that increase bioavailability of minerals
Deficiency in a mineral increases absorption
Cooking increases the bioavailability of minerals in legumes
Vitamin C increases the absorption of some minerals such as iron
Factors that reduce bioavailability of minerals
Binders, such as OXALATES found in some veggies.
PHYTATES found in grains
POLYPHENOLS in tea and coffee
Supplementation of single minerals affects absorption of competing minerals
Example of an oxalate
One that binds with the calcium in spinach.
The 10 trace elements are…
Iron Zinc Copper Selenium Fluoride Iodine Chromium Cobalt Manganese Molybdenum
Sources of Iron
Meat, fish, poultry, eggs, dried peas and beans, whole grains and fortified breads and cereals.
Forms of Iron
3-4 grams of Fe in adult body
Two forms:
Ferrous iron (+2)
Ferric iron (+3)
How is iron transported in circulation?
Bound to TRANSFERRIN.
Most of the iron (70%) is in _ _ _s as part of _ _ _ _ in hemoglobin.
RBCs, heme
5% is bound to myoglobin in heart and skeletal muscles.
5% act as cofactor either part of heme or non-heme enzymes.
Where is iron stored?
RBCs, heme, myoglobin, cofactor…
FERRITIN in liver, spleen, and bone marrow.
When iron concentrations are high, liver converts _______ into another storage protein called _______
When iron concentrations are high, liver converts FERRITIN into another storage protein called HEMOSIDERIN.
Where is Hemosiderin found?
In macrophages, especially abundant in situations following hemorrhage (its formation may be related to phagocytosis of RBCs and hemoglobin)
What two forms of dietary iron are found in food?
- Heme - absorbed slowly, not affected by dietary composition.
- Non-heme - the larger portion of iron consumption is from non-heme iron which includes both plant and animal sources.
Non-heme iron is absorbed at a much ______ rate than the heme molecule.
SLOWER
T or F: Only foods derived from animal flesh provide heme, but they also contain noontime iron.
True
T or F: All of the iron in foods derived from plants is non-heme iron.
True.
Which is absorbed better: heme iron or non-heme iron?
Heme (25% absorbed), even though it accounts for less (10%) of the average daily iron intake.
Non-heme - accounts for 90% but less well absorbed (about 17%).
Factors that ENHANCE non-heme absorption
Body need (ex. periods of growth, pregnancy, weight training)
Vitamin C (Ascorbic acid - acidic environment increases iron absorption)
Animal tissues (presence of Meat Protein Factor - MPF: a peptide in meant, fish and poultry that promote the absorption of non-heme iron. Heme iron improves non-heme iron)
Sugars (fructose)
Acids (citric and lactic)
Factors that INHIBIT non-heme absorption
Binding agents (oxalates, phytates, polyphenolsm, fiber)
Low gastric acid
Infection (body suppresses supply of iron in an attempt to reduce supply to infectious organisms).
GI disease
Calcium, zinc, and manganese
Antacids and proton pump inhibitors
Minerals found in CHILI DINNER
Provides iron, MFP from meat, iron from legumes, Vitamin C from tomatoes :)
Where is excess iron stored? Describe the absorption of iron: When the body needs it vs. when it doesn’t.
Mucosal cells in the intestine store excess iron in mucosal FERRITIN (storage protein).
It’s found in food. If body needs iron: Little ferritin is made (more can bind transferrin). Mucosal ferritin releases iron to mucosal TRANSFERRIN (transport protein) which hands off iron to another transferrin that travels through the blood to the rest of the body.
If body does not need iron - iron is not absorbed and is excreted in shed intestinal cells. Thus, absorption is reduced when not needed.
Where is iron absorbed?
Duodenum
Describe the absorption of iron.
Heme iron is transported across brush border and enters same pool as non-heme iron. Dietary non-heme iron (ferric, + 3) must be reduced to ferrous (+2) for transport across the brush border.
Some iron issued or stored within the enterocytes and lost when the intestinal mucosa is sloughed.
Ferroportin helps to transport iron out of enterocytes for incorporation into serum transferrin Ceruloplasmin - Fe2+ to Fe3+
The amount of ferritin produced in this cell is proportional to the iron in body stores.
What is CERULOPLASMIN?
Aka ferroxidase (hephaestin) 1. It takes ferrous form and makes it into ferric form - important because what's need to bind to transferase! If you don't need iron, will be kept as ferritin.
- THE MAJOR COPPER CONTAINING PROTEIN IN PLASMA.
How is iron recycled in the body?
Once in circulation, transferrin bound iron is distributed to liver, muscle, bone marrow, other body tissue (bone marrow incorporates iron to hemoglobin of RBCs, excess stored in ferritin and hemosiderin. Some delivered to myoglobin of muscle cells. Some lost if bleeding occurs).
Liver and spleen degrades old RBCs and they harvest iron from them for recycling - pack into transferrin and ferritin and hemosiderin.
Some is lost with sweat, skin, urine, body tissues and must be replaced by eating iron-containing food
Who is vulnerable to iron deficiency?
Women in reproductive years, pregnancy, infants and young children, adolescents.
Inadequate intake
A diet with low bioavailable iron (ex. infants not given iron-fortified formula or cereal after 6 months of age).
Vegans
Symptoms of iron deficiency
Fatigue, feelings of faintness, cold or abnormal sensations of the extremities, shortness of breath (first 4 due to iron-deficiency anemia), greater susceptibility to infections, low IQ infants.
PICA!
HYPOCHROMIC MICROCYTIC ANEMIA
Why does iron deficiency lead to immunosuppression?
Role of heme iron as a prosthetic group in several enzymes needed to destroy microorganisms.
Why does iron deficiency lead to low IQ?
Due to the altered neurotransmitter synthesis.
Reduces work capacity and mental productivity. Motivational problems.
What is Pica?
The craving and consumption of unusual nonfood substances such as dirt, clay, or ice (comes with iron OR ZINC deficiency)
Describe iron’s role in neurotransmitter synthesis enrichment
Essential for tryptophan hydroxylase (serotonin) and tyrosine hydroxylase (norepi and DA).
Iron is a cofactor for ribonucleotide reductase and is essential for function of a number of electron transfer reactions related to lipid and brain-energy metabolism.
Iron related to monoamine oxidase activity - enzyme critical for proper rates of degradation of these neurotransmitters.
Stages of Iron deficiency development:
- Iron stores diminish (serum ferritin)
- Transport decreases (TIBC Total Iron-binding Capacity or transferrin saturation)
- Hemoglobin production and hematocrit falls.
Most commonly used tests to uncover iron deficiency:
Hemoglobin and hematocrit
As serum iron falls, transferrin levels (increase or decrease)?! as an adaptation mechanism.
Increase.
What is Total Iron-Binding Capacity (TIBC)?
A measure of total amount of iron that transferrin can carry.
What is Transferrin saturation?
% Transferrin = (serum iron/total iron binding capacity) * 100
Serum Ferritin
Provides a good estimate of iron stores.
Not a reliable indicator as the concentrations are increased by infection, inflammation, alcohol consumption, and liver disease.
