nutr - micronutrients

  1. what are micronutrients?
    • needed in the diet in small amounts
    • not endogenously synthesized at suffient rates to meet requirements
    • perform specific biological functions
  2. what happens if micronutrients are withdrawn/ommitted from diet?
    results in deficiency
  3. how do you a correct deficiency?
    by adding nutrient back into the diet
  4. what is bioavailability?***
  5. what is the most abundant mineral in the body?
    calcium = 1150g in a 60kg person
  6. what are vitamins?
    • essential organic nutrients required in small amounts (mg or ug)
    • many are susceptible to degradation in food
  7. how do vitamins generally function as?
    they function as coenzymes
  8. what are vitamers?
    different from of a vitamin can have different functions, conversion between forms and form precursors
  9. what are the fat soluble vitamins?
    Vitamins A, D, E, K
  10. what are the water soluble vitamins?
    Vitamins Bs and C
  11. what are complex B vitamins used in?
    • intermediary metabolism
    • B1 (thiamin) = coenzyme for pyruvate decarboxylation
    • B2 (riboflavin) = coenzyme for FAD, FMN
    • B3 (niacin) = coenzyme for NAD, NADP
    • B5 (pantothenic acid) = CoA in acetyl CoA
    • B6 (pyridoxine) = coenzyme in transamination reactions
  12. how do coenzymes work?
    • 1. Enzyme is inactive without coenzyme
    • chemical compound cannot bind to enzyme
    • chemical reaction cannot take place

    • 2. Enzyme is activated by addition of coenzyme
    • compound binds to enzyme
    • chemical reaction takes place
  13. what are the hormonal functions of vitamins?
    Vitamin A (as retinoid acid) = cell differentiation

    Vitamin D (as calcitriol) = calcium availability
  14. what are the antioxidant functions of vitamins?
    • Vitamins C and E
    • e = lipid soluble antioxidant
    • imp. in protein lipid membranes in FAs that are being oxidized
  15. what are the 2 nutritional anemias?
    • 1. hypochromic microcytic anemia
    • 2. megaloblastic or pernicious anemia
  16. what causes hypochromic microcytic anemia?
    • iron deficiency
    • most common form of anemia
    • RBCs are pale, low in color and smaller than normal
    • hemoglobin content = ↓
  17. where is hypochromatic microcytic anemia found in?
    women and children
  18. what causes megaloblastic or pernicious anemia?
    • folate of vitamin B12 deficiency
    • really big RBCs that don't mature properly
    • don't carry O2 well
    • hangs on and won't go away
    • B12 deficiency = most likely pernicious
  19. where is megaloblastic or pernicious anemia found in?
  20. what are the different functions of iron?
    • to transfer oxygen
    • as part of a Heme group in a protein
  21. what is hemoglobin?
    transport of oxygen in a protein
  22. what is myoglobin?
    • for muscle storage of oxygen
    • muscle binds to iron
    • short term reservoir of oxygen in muscle
  23. what does heme do?
    • transport of electrons through respiratory chain (cytochromes)
    • many enzymes such as peroxidase, myeloperoxidase, catalase
  24. what is the iron composed of (structure)?
    4 protein units + Fe center

    ironically, heme is made of AA but its NOT a protein!!!
  25. whats the difference between hypochromic microcytic anemia and normochromic normocytic cells?
    normocytic cells = biconcave disk to maximize surface area for O2
  26. what are signs and symptoms of iron deficiency anemia?
    • tiredness
    • ↓ work performance
    • ↓ childhood development - psychomotor and intellectual
    • ↑ lead poisoning susceptibility
    • (Pb2+ causes brain damage)
  27. iron deficiency anemia in men and women
    • men = Hgb <140g/L
    • women = Hgb < 120g/L
  28. what is the prevalence of IDA?
    • Developing countries
    • 50% of women and children, 25% of men

    • Developed countries
    • 7-12% of women and children
    • 25% of low income infants in Montreal

    4-5 billion people are deficient in iron
  29. why are women and children at increased risk of IDA?****
    EAR for women = ↑er than for men
  30. how does iron metabolism work?***
    • Fe2+ (ferrous iron) = absorbed in the intestinal eithelial cells
    • it binds to the protein ferritin
    • when iron is bound to a transporter, it is oxidised
  31. what is iron balance?
    • iron intake = iron loss
    • iron intake : dietary iron and its bioavailability
    • amount of iron in storage
    • rate of erythrocyte production (RBCs)
    • iron loses
  32. assessment of iron storage
  33. what are the sequential changes with development of iron deficiency?
    • 1. Depletion of iron stores
    • ↓ plasma ferritin

    • 2. Changes in iron transport
    • ↑ absorption efficiency
    • ↑ transferrin iron binding capacity
    • ↓ transferrin saturation %
    • ↑ transferrin receptors

    • 3. Defective erythropoiesis
    • plasma iron
    • ↑ free erythrocyte protoporphyrin

    • 4. Iron deficiency anemia
    • microcytic hypochromatic erythrocytes
    • associated behavioural signs
  34. what are the causes of iron deficiency?
    • 1. Decreased ↓ dietary iron
    • less iron is absorbed
    • vegetarian diets lack heme

    • 2. Inhibition of absorption
    • mineral interaction: calcium, zinc supplements can ↓ iron absorption

    • 3. Increased ↑ red cell mass
    • pregnancy
    • growth

    • 4. Increased ↑ losses
    • hemolysis
    • GI bleeding (occult)
    • Heavy menstrual losses
    • undiagnosed colon cancer
  35. what are some treatments for IDA?
    • change in diet
    • taking iron supplement: ferrous sulphate (FeSO4)
    • retst hemoglobin = to see if its a secondary deficiency due to heavy bleeding (menstruation), malabsorption
  36. what are some methods to prevent IDA?
    • fortify food supply: pasta and grains are already fortified with FeSO4 because of a law
    • there are pro/cons
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nutr - micronutrients