Exam 3: Chapter 15 Flashcards
Food Sources of Heme Iron
- very bioavailable
- most meats and seafood
Food Sources of Non-heme Iron
- not as bioavailable
- Vegetables, grains, beans and supplements
What factors affect Iron absorption?
- 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
- Nonheme hindered by dietary factors
- Gastric contents acidity
- Promotes conversion of ferric (Fe3+) to ferrous (Fe2+)
Functions of Iron
-
Redox reactions
- Ferrous (Fe2+) to ferric (Fe3+)
- Can be damaging produce free radicles
- Ferrous (Fe2+) to ferric (Fe3+)
-
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
What groups of people are at greatest risk for iron deficiency anemia?
Premature infants, young children, females of childbearing age, vegetarians
Food Sources of Zinc
Protein-rich meat and seafood also nuts, beans, and whole grains
Functions of Zinc
- As many as 300 different enzymes require zinc
- DNA and RNA synthesis, heme synthesis, bone formation, taste acuity, immune function, reproduction, growth, etc.
Zinc Deficiency
- Overt deficiency common when poverty limits food choices
- North America: mild or marginal deficiencies
- malabsorptive diseases, dialysis, limiting animal foods
Main functions of Copper
- Component of enzymes
- Cu1+ and Cu2+
- Superoxide dismutase enzymes (SOD)
- Eliminate superoxide free radicals
- Electron transport chain
- Cytochrome C oxidate
Main Functions of Manganese
- Shares functional similarities with Zinc and Copper
- Carbohydrate metabolism, gluconeogenesis, collagen formation, antioxidant system, etc.
Main functions of Selenium
- Antioxidant defense network
- Glutathione peroxidase
- Thyroid metabolism (T4 to T3), immune function, etc.
Main functions of chromium
- Not fully know
- May enhance insulin function and promote glucose uptake
Main functions of flouride
- Deposition of Ca and P in teeth and bones
- Promotes bone and dental health
Main functions of Iodine
- Essential component
- Thryoxine (T4) –majority in body
- Triodothyronine (T3)—active form
- Enzyme needed for this conversion to T3 is selenium
What is Iodine Deficiency Disorders (IDD)?
- Iodine Deficiency Disorders (IDD)
- Endemic goiter—thyroid hormone enlarges to “trap” more iodine
- Endemic cretenism—restriction of brain development and growth
- In fetus
Food Sources of Flouride
Fluoridated water, tea, seafood, and seaweed
Food Sources of iodine
- 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
- Concern in less developed parts of world
Food Sources of Selenium
- Dependent on soil content
- Seafood, meats, cereal, and grains
- Rice
signs and symptoms of zinc toxicity
- Abdominal pain, nausea, vomiting and diarrhoea.
- Other reported effects - these include gastric irritation, headache, irritability, lethargy, anaemia and dizziness.
What is the difference between heme and non-heme sources of iron?
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.
