NUTR 337-9

Card Set Information

NUTR 337-9
2013-02-24 12:42:09
Macromineral requirements during pregnancy

Macromineral requirements during pregnancy
Show Answers:

  1. What is the calcium RDA dependent on?
    • Relies on Ca balance studies
    • Intakes at which small gains in bone mineral content can be achieved
    • Based on clinical trial data showing an increase in bone mineral density in women provided with intakes of 1000mg/day
  2. How many people consume the recommended amount of calcium?
    Only ~13% of males and 4% of females consume 100% of the recommendation (1200mg/day)
  3. What are some risks of calcium deficiency?
    • Increased risk of osteoporosis
    • Hypertension
    • Colon cancer
  4. How much calcium is transferred to the fetus during pregnancy?
    • ~25-30g of Ca transferred to the fetus
    • The majority of this transfer occurs during the 3rd trimester
  5. Why is there an increase in calcium absorption during pregnancy?
    Increase in blood [1,25(OH)D] during pregnancy
  6. How much additional calcium is required during pregnancy?
    No evidence supports increased need for dietary calcium during pregnancy
  7. Where is most phosphorous found in the body?
    85% of the adult body phosphorous is in bone
  8. Why is phosphorous important?
    • Buffers acid or alkali excess to maintain normal pH
    • Temporary storage and transfer of the energy derived from metabolic fuels
    • Required for phosphorylation, the activation of many catalytic proteins
  9. How much additional phosphorus is required during pregnancy?
    • No evidence to support a increase in EAR for phosphorus
    • Intestinal absorption is increased by 10% during pregnancy, which is sufficient for fetal needs
  10. Where is magnesium found in the body?
    • 50-60% in bone
    • 1/3 of skeletal Mg is exchangeable as a reservoir for maintaining a normal extracellular [Mg]
  11. What is the function of magnesium?
    required cofactor for 300 enzymes
  12. Why do elderly people require more magnesium?
    • With age, there is an increase in high fiber diets
    • Renal function is critical to maintenance of Mg status; and declines with age
  13. Why is there a need for more magnesium during pregnancy?
    • Decrease in serum [Mg], thought to be due to hemodilution
    • No data indicating that Mg is conserved during pregnancy or intestinal absorption is increased
    • Weight gain alone may result in a greater requirement for Mg
  14. What is the additional requirement for magnesium during pregnancy?
  15. What is the function of iron?
    • Component of a number of proteins, including enzymes and hemoglobin
    • Almost 2/3 of Fe is found in hemoglobin present in circulating erythrocytes
    • 15% of myoglobin in muscle tissue
    • Variety of enzymes necessary for oxidative metabolism and many other critical functions
  16. What are the factors used to determine Fe requirement?
    • Basal iron losses
    • Menstrual losses
    • Fetal requirements during pregnancy
    • Growth: expansion of blood volume and/or increased tissue and iron storage
  17. What are some basal losses of iron?
    Obligatory losses in feces, urine, and sweat and from the exfoliation of skin cells
  18. How is dietary absorption determined?
    • The proportion of dietary iron absorbed is determined by the iron requirement of the individual
    • Body Fe store regulates absorption (% absorbed is inversely proportional to serum [ferritin])
  19. What type of iron is more bioavailable?
    Heme iron
  20. Why is nonheme iron not as good?
    Strongly influenced by its solubility and interaction with other meal components in upper intestinal lumen
  21. What bioavailability is used to estimate iron requirements on a typical mixed diet?
  22. Which group of individuals has the highest iron requirement?
    Women ages 19-50 (due to menstrual losses)
  23. What are the consequences of iron deficient anemia during pregnancy for the mother?
    • Severe anemia can lead to perinatal maternal mortality
    • Moderate anemia is associated with a two-fold risk of maternal death
    • Causes of death such as heart failure, hemorrhage, infection
  24. How does iron deficiency during pregnancy affect the fetus?
    Maternal anemia is associated with premature delivery, low birth weight, and increased perinatal infant mortality
  25. Why is iron so important during pregnancy?
    • Fe deficiency limits the expansion of maternal erythrocyte cell mass
    • Decreases hemoglobin synthesis, increases workload of maternal hear to supply fetus with O2 which can lead to abnormal fetal development
  26. Why must pregnant women take iron supplements?
    • Habitual canadian diet cannot meet such high Fe RDA
    • Supplementation uses the assumption of inadequate pre-pregnant Fe stores
  27. What is used to determine the pregnancy RDA for iron?
    Set by estimating the requirement for absorbed Fe at the 97,5 percentile and using an upper limit of 25% iron absorption and rounding