Exam 3: Chapter 15

Question 1

Food Sources of Heme Iron

Answer 1

• very bioavailable
• most meats and seafood

Question 2

Food Sources of Non-heme Iron

Answer 2

• not as bioavailable
• Vegetables, grains, beans and supplements

Question 3

What factors affect Iron absorption?

Answer 3

• Body’s iron needs and stores
  
  • Adequate ~15% (14% to 18%)
  • Low ~35% to 40%
  • High ~5%
• Form of iron in foods eaten
  
  • Heme vs nonheme
• Dietary composition
  
  • Nonheme hindered by dietary factors
    
    • Oxalic acid and phytic acids
    • Polyphenols (tannins)
    • Increased by vit C
• Gastric contents acidity
  
  • Promotes conversion of ferric (Fe3+) to ferrous (Fe2+)

Question 4

Functions of Iron

Answer 4

• Redox reactions
  
  • Ferrous (Fe2+) to ferric (Fe3+)
    
    • Can be damaging produce free radicles
• Part of Hemoglobin and Myoglobin
  
  • Transport and metabolism of oxygen
• Iron-containing enzymes
  
  • Energy metabolism, mitochondrial cytochromes,
  • Drug metabolism in liver by iron containing enzymes
• Enzyme co-factor
  
  • Synthesis of neurotransmitters
  • Production of immune system components

Question 5

What groups of people are at greatest risk for iron deficiency anemia?

Answer 5

Premature infants, young children, females of childbearing age, vegetarians

Question 6

Food Sources of Zinc

Answer 6

Protein-rich meat and seafood also nuts, beans, and whole grains

Question 7

Functions of Zinc

Answer 7

• As many as 300 different enzymes require zinc
• DNA and RNA synthesis, heme synthesis, bone formation, taste acuity, immune function, reproduction, growth, etc.

Question 8

Zinc Deficiency

Answer 8

• Overt deficiency common when poverty limits food choices
• North America: mild or marginal deficiencies
• malabsorptive diseases, dialysis, limiting animal foods

Question 9

Main functions of Copper

Answer 9

• Component of enzymes
  
  • Cu1+ and Cu2+
• Superoxide dismutase enzymes (SOD)
  
  • Eliminate superoxide free radicals
  • Electron transport chain
  • Cytochrome C oxidate

Question 10

Main Functions of Manganese

Answer 10

• Shares functional similarities with Zinc and Copper
• Carbohydrate metabolism, gluconeogenesis, collagen formation, antioxidant system, etc.

Question 11

Main functions of Selenium

Answer 11

• Antioxidant defense network
  
  • Glutathione peroxidase
• Thyroid metabolism (T4 to T3), immune function, etc.

Question 12

Main functions of chromium

Answer 12

• Not fully know
• May enhance insulin function and promote glucose uptake

Question 13

Main functions of flouride

Answer 13

• Deposition of Ca and P in teeth and bones
• Promotes bone and dental health

Question 14

Main functions of Iodine

Answer 14

• Essential component
  
  • Thryoxine (T4) –majority in body
  • Triodothyronine (T3)—active form
    
    • Enzyme needed for this conversion to T3 is selenium

Question 15

What is Iodine Deficiency Disorders (IDD)?

Answer 15

• Iodine Deficiency Disorders (IDD)
  
  • Endemic goiter—thyroid hormone enlarges to “trap” more iodine
  • Endemic cretenism—restriction of brain development and growth
    
    • In fetus

Question 16

Food Sources of Flouride

Answer 16

Fluoridated water, tea, seafood, and seaweed

Question 17

Food Sources of iodine

Answer 17

• Saltwater seafood, seaweed, iodized salt, and dairy products
• Goitrogens decrease bioavailability of iodine and inhibit use of iodine by thyroid gland
  
  • Concern in less developed parts of world
    
    • High veggie intake—but cooking destroys goitrogens

Question 18

Food Sources of Selenium

Answer 18

• Dependent on soil content
• Seafood, meats, cereal, and grains
• Rice

Question 19

signs and symptoms of zinc toxicity

Answer 19

• Abdominal pain, nausea, vomiting and diarrhoea.
• Other reported effects - these include gastric irritation, headache, irritability, lethargy, anaemia and dizziness.

Question 20

What is the difference between heme and non-heme sources of iron?

Answer 20

Heme iron from animmal sources is very bioavailable, meaning it is more efficient and more easily absorbed. Non-heme sources are from plant sources, are not as bioavailable in the body, and therefore not as easily absorbed.