Ch. 13 Trace Minerals

Question 1

Name the trace minerals

Answer 1

Iron and Zinc (Manganese, Iodine, Selenium, Copper)

Question 2

Describe characteristics of trace minerals. Why are they called trace? What generally causes toxic levels? What influences minerals in foods? Who is impacted by deficiency?

Answer 2

Characteristics: They participate in diverse tasks all over the body, each having special duties that only it can perform.

Called Trace: Needed in very small quantities in the human body BUT they perform many essential functions important to health

Toxic levels: taking supplements with dietary foods = too much trace minerals.

Deficiency: anemics, people with poor diets (or vegan/vegetarian diets)
–*everyone can be impacted by deficiency…but deficiencies are rarer in our American diets. The above listed groups are at a higher risk for deficiencies/anemics already have the deficiencies.

Question 3

Zinc

Answer 3

Fxn:

• promotes cell production/growth/repair
• part of many enzymes
• wound healing

Deficiency: not widespread in American diet

• growth retardation
• sores around mouth
• delayed wound healing (sores around mouth!!)

Toxicity: TUL established (adults: 40 mg/d)

• loss of appetite
• impaired immunity
• low HDL
• copper and iron deficiencies

Food Sources: meat, milk, poultry, cheese

Question 4

Iron

Answer 4

Fxn:

• cofactor
• enzymes involved in making amino acids/collagen/hormones/neurotransmitters require iron
• transfer hydrogens and electrons to oxygen
• forming water –> make ATP for the cell energy use

Recommendations:

• Adults (19-50) RDA:
• ->males: 8 mg/d
• -> females: 18 mg/d
• Pregnancy: all ages = 27 mg/d
• TUL (all adults) 45 mg/d

Deficiency: anemia

• -loss of energy, shortness of breath
• -> Small/pale blood cells because they contain less hemoglobin (w/o iron, hemoglobin doesn’t form, less O2 transport)

Food Sources: meat, fish, poultry, legumes, eggs
–animal sources (heme iron), plant sources (nonheme iron)

Question 5

What is hemoglobin and what is its relationship to iron?

Answer 5

Hemoglobin: oxygen-carrying protein of the RBCs that TRANSPORTS oxygen from the lungs to tissues throughout the body
–> hemoglobin accounts for 80% of the body’s iron

Question 6

What is myoglobin and what is its relationship to iron?

Answer 6

The oxygen-holding protein of the muscle cells.

–> Body’s iron found here in addition to hemoglobin.

Question 7

Describe iron absorption in the body. What is the sequence of absorption?

Answer 7

1. iron-storage protein (ferritin) captures iron from food and stores it in the cells of the small intestine.
2. when the body needs iron, ferritin releases some iron to an iron transport protein called transferrin.
3. if the body does not need iron, it is carried out when the intestinal cells are shed and excreted in the feces

Question 8

What is ferritin?

Answer 8

Iron storage protein

Question 9

What is the role of transferrin?

Answer 9

Iron transport protein

Found in blood, glycoproteins…

Question 10

In general, how much dietary iron is absorbed?

Answer 10

Overall, about 18% of dietary iron is absorbed from mixed diets
–> only about 10% from vegetarian diets

Question 11

What does the body do to adapt to its iron needs? Where is surplus iron stored?

Answer 11

Excreting iron from the body is difficult. Body will absorb more iron as it’s needed, and absorb less iron when iron is NOT needed in body.

Surplus iron is stored in the protein ferritin, primarily in the liver, but also in the bone marrow and spleen.

Question 12

Differentiate between heme and nonheme iron sources in food. What are food sources of each? How much (%) of a typical diet is comprised of each? How does the absorption rate (%) differ between the two?

Answer 12

Heme: [animal sources] meat, poultry, fish.
–heme iron accounts for 10% of average daily iron intake, but it’s well absorbed (25%)

Nonheme: plant-derived foods, some also found in animal sources.
–nonheme iron accounts for remaining 90% of average daily iron intake, but it’s less well absorbed (about 17%)

Question 13

Identify factors that enhance and inhibit iron absorption.

Answer 13

Enhance:

• -vitamin C
• -MFP factor (meat, fish, poultry)

Inhibit:

• -phytates
• -oxalates
• -calcium and phosphorus in milk
• -tannic acid (teas and coffee)

Question 14

Describe iron recycling.

Answer 14

Transferrin carries iron in blood. Marrow incorporates iron into hemoglobin of RBCs and stores excess iron in ferritin. Iron containing RBCs carry oxygen. Liver and spleen dismantle RBCs, package iron into transferrin, and store excess iron in ferritin. Cycle repeats

(*Some iron lost through sweat, skin, urine, myoglobin of muscle, bleeding)

Question 15

Define anemia. What are the 3 major causes of anemia? What 3 nutrients are associated with anemia? What physiological states contribute to these types of anemia?

Answer 15

Def: Anemia is any condition in which too few RBCs are present, or the RBCs are immature (and therefore large) or too small or contain too little hemoglobin to carry the normal amount of oxygen to the tissues.

3 Major Causes:

• -iron deficiency-anemia: RBCs are microcytic and pale b/c they contain less hemoglobin
• -Pernicious anemia (B12): physiological and surgical causes
• -Folate anemia: macrocytic or megaloblastic anemia and is characterized by large, immature red blood cells

3 Nutrients:
–Vitamin B9 (Folate), Vitamin B12 (Cobalamin), and Iron