Trace Minerals

Question 1

Iron - function and absorption

Answer 1

• most of the iron in the body is a component of hemoglobin in red blood cells and myoglobin in muscle cells
• helps hemoglobin and myoglobin carry and hold oxygen and then release it
• myoglobin holds oxygen for the muscles to use when they contract
• significant iron losses with bleeding
• to ensure that enough iron is available to meet the body’s needs and yet guard against excessive and damaging levels, special proteins transport and store the body’s iron supply and its absorption is tightly regulated.
• no active means of excreting excess iron. regulating absorption plays critical role in iron homeostasis

Question 2

Iron - role of transferrin

Answer 2

• 10-15% of dietary iron is absorbed
• a special protein in the intestinal cells captures iron and holds it in reserve for release into the body as needed. another protein will transfer it to transferrin
• transferrin (another protein), an iron carrier, in the blood. carries the iron to tissues throughout the body. when more iron is needed, more of these proteins are produced so that more than the usual amount of iron can be absorbed and carried.

Question 3

Iron storage proteins: ferritin and hemosiderin

Answer 3

store iron in the bone marrow, liver, and other organs
- ferritin (30%)
- RBC + Muscle (Fe in heme) 67%
- 3% lost in sweat, urine, bile, intestines

Question 4

Hepcidin: hormone central to iron balance

Answer 4

• Reduces iron’s absorption from the intestine and release from storage
• works in an elegant feedback system to control blood iron

Question 5

Functions of Iron

Answer 5

Hemoglobin: oxygen-carrying protein of the RBC
Myoglobin: oxygen-carrying protein of the muscle cell
Iron in both helps carry and hold oxygen and then release it

Question 6

Iron Cycle and Losses of Iron

Answer 6

Intakes -> iron in the blood -> enters bone marrow (ferritin) -> creates new hemoglobin -> liver breaks down hemoglobin -> either back to iron in the blood or lost
- Loses of Iron: loss of cells: mucosal, skin. Blood loss: injury, traumatic or due to disease, blood donations, menstrual losses

Question 7

Iron deficiency worldwide

Answer 7

• worldwide, the most common nutrient deficiency
• iron is especially important for women in reproductive years, pregnant women, infants, toddlers, and adolescents
• Iron deficiency: the condition of having depleted iron stores
• Iron deficiency anemia: a blood iron deficiency characterized by small, pale RBC; also called microcytic hypochromic anemia
• Causes: inadequate intake, blood loss

Question 8

Iron Deficiency Anemia

Answer 8

• the severe depletion of iron stores that results in a low hemoglobin concentration.
• RBC cant carrry enough oxygen from the lungs to the tissues. without adequate oxygen energy metabolism in the cells falters
• S&S: fatigue, weakness, headaches, apathy, pallor, and poor resistance to cold
• skin is pale

Question 9

Iron Deficiency Stage 1

Answer 9

both iron stores and ferritin levels diminish. Measure of serum ferritin are most valuable in assessing iron status at this early stage; minimal to no symptoms; no overt effect on RBC formation

Question 10

Iron Deficiency Stage 2

Answer 10

characterized by decrease in transport iron; levels of serum iron fall, levels of iron-carrying protein transferrin increase; total iron-binding capacity measures the total amount of iron that the blood can carry; start seeing symptoms: chronic fatigue, irritability, and trouble concentrating

Question 11

Iron Deficiency Stage 3

Answer 11

iron-deficiency anemia; lack of iron limits hemoglobin production. The hemoglobin precursor, erythrocyte protoporphyrin, begins to accumulate, hemoglobin and hematocrit values decline

Question 12

S&S Iron Deficiency - Early

Answer 12

unmotivated, apathetic, less physically fit, progresses to chronic fatigue, irritability and trouble concentrating, progresses to fatigue, weakness, headaches, apathy, pallor, poor resistance to cold temperatures

Question 13

Nutrition related causes of anemia

Answer 13

• Iron
• Low Vitamin B12 or Folate

Question 14

Iron Toxicity

Answer 14

• Iron overload: toxicity from excess iron
• hemochromatosis: characterized by deposits of iron-containing pigment in many tissues, with tissue damage. Usually caused by a hereditary defect
• iron poisoning in children is medical emergency
• continual build-up, needs strict avoidance

Question 15

Iron in food

Answer 15

Animal source -> heme iron
- based on hemoglobin & myoglobin in animal proteins
- absorb - 25% but only 10-15% of iron in a mixed diet
Plan-based -> non-heme iron
- whole grains, legumes, dark green veg, enriched refined grains. poorly absorbed (2-10%), impacted by other dietary factors

Question 16

Absorption of Non-Heme Iron

Answer 16

Enhancers
- vit. C
- organic acids (citric acid, malic acid, tartaric, lactic acid)
- meat, fish, poultry, adequate copper status, cooing in iron pan

Inhibitors
- phytates - legumes, grains, rice decrease absorption by 50% tannins/tannic acid - tea. calcium and phosphorus and large zinc doses

Question 17

Zinc

Answer 17

• required by >300 enzymes
• needed for many processes/functions
• how does the body’s handling of zinc resemble that of iron? like iron, it is held in the intestinal cells and only what is needed is excreted and the amount of zinc in the body influences absorption
• main blood transport vehicle: albumin
  Deficiency: rare in developed nations. risk: pregnant teens, vegetarians
  Toxicity: produces copper-deficiency anemia
• UL: 40 mg/day
  Abundant in high-protein animal foods

Question 18

Selenium

Answer 18

• Functions as an antioxidant nutrient
• needed for proper functioning of the iodine-containing thyroid hormone
• adequate blood selenium seems protective against prostate, colon, and other cancers
• Deficiency: predisposes to Keshan disease (heart disease)
• Toxicity: UL set, vomiting, diarrhea, hair/nail loss/lesions
  Recommendations and intakes
• widely distributed in foods such as meats, shellfish, vegetables, and grains grown in selenium-rich soil, brazil nuts

Question 19

Iodine

Answer 19

• integral part of the thyroid hormones
  regulate body temperature, metabolic rate, reproduction, growth, blood cell production, ect.
• iodine deficiency: goiter: enlargement of the thyroid gland, preventable mental retardation and brain damage, cretinism: mental and physical retardation caused by iodine deficiency during pregnancy
  Toxicity: enlarges thyroid gland. UL for adults 1100 ug/day
  Sources: seafood, water, sea mist, table salt
  RDA: 150ug/day

Question 20

Copper

Answer 20

Primary Function: constituent of enzymes
- diverse metabolic roles
helps cells use iron
- Deficiency: rare; high zinc intakes
- Toxicity: genetic disorder
Recommendations
RDA: 900 ug/day

Question 21

Manganese

Answer 21

cofactor for many enzymes
- facilitate numerous metabolic processes
UL: 11mg/day

Question 22

Fluoride

Answer 22

• strengthens teeth; prevents dental decay
• Fluoride deficiency: increased dental decay
• fluoride sources: fluoridated water, toothpaste, fish, tea

Question 23

Chromium

Answer 23

• essential in carbohydrate and lipid metabolism
• enhances the activity of insulin
• deficiency causes diabetes-like condition
• best sources: unrefined foods (liver, brewer’s yeast, whole grains, nuts, and cheeses)

Question 24

Molybdenum

Answer 24

• functions as a working part of several metal-containing enzymes
• nickel, silicon, cobalt, boron