NUTR 337-4

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NUTR 337-4
2013-02-21 14:12:41
Nutrient requirements lactation

lecture 6/7
Show Answers:

  1. How is milk energy output computed?
    Milk energy output is computed from milk production and the energy density of human milk
  2. What factors affect the incremental energy requirements for lactation?
    The stage and extent of breastfeeding affect the incremental energy requirements for lactation
  3. Do women experience weight loss during lactation?
    In general, during the first 6 months postpartum well-nourished lactating women experience a mild, gradual weight loss, averaging 0.8kg/mo
  4. What area of adipose tissue is generally mobilized in the first 6 months postpartum?
    • In the first 6 months postpartum, the subcutaneous region accounted for the entire reductio in adipose tissue volume, which decreased from 23.2L to 20.0L
    • Non-subcutaneous adipose tissue volume actually increased
  5. What are the mean milk production rates of American women?
    • 0.78L/day in term infants from birth through 6 months
    • 0.6L/day in term infants from 7-12 months of age
  6. How is the EER for lactation calculated?
    EER=Adult/adolescent EER (depending on age)+milk energy output-weight loss
  7. Does the protein content in human milk change with the mothers diet?
    No. The concentration of protein in human milk is not influenced by diet or body composition even in undernourished mothers
  8. How much protein is required to maintain good milk production in healthy mothers?
    Protein intakes of 1g/kg body weight/day are needed to promote the conservation of skeletal muscle in order to maintain good milk production in lactating mothers
  9. How is protein intake for lactating women determined?
    • Factorial approach is utilized
    • It is assumed that the process of lactation does not alter the maintenance protein requirement
    • AND
    • Protein and/or amino acid requirement is increased in proportion to milk production
  10. Describe the levels of non-protein nitrogenous substances in human milk.
    • Human milk is characterized by a relatively high concentration of non-protein nitrogenous substances.
    • Non-protein nitrogenous substances contribute approximately 20-27% of total milk nitrogen
  11. What is the quantitatively important non-protein nitrogen component in milk?
  12. Where do mothers get their increased nitrogen needs?
    It is assumed that part of the increased nitrogen needs of the lactating woman to produce milk non-protein nitrogen will come from dietary protein
  13. How was the protein EAR for lactating women calculated?
    • The average protein equivalent of human milk nitrogen output during the first 6 months of lactation was divided by the average incremental efficiency of dietary protein utilization¬†
    • The values for the various moths of lactation were then averaged to set the amount by which the EAR for non-lactating women should be increased by as +21g/day
  14. What is the protein EAR for lactating women?
    1.05g/kg/day or +21g/day additional protein
  15. What is the protein EAR for non-lactating women?
  16. What is the protein EAR for lactating women?
  17. What is the protein RDA for non-lactating women?
  18. What is the protein RDA for lactating women?
  19. How is the protein RDA for lactating women calculated?
    • RDA (non-lactating)=0.8g/kg/day
    • CV-12%
    • RDA=EAR+24%
    • Requirement for protein losses during lactation = 21.2
    • 21.3x1.24=26.3 (rounded to 25)
    • 26.3/57(average weight)=0.46 (increase factor)
    • RDA (lactating)=0.8+0.46=.1g/kg/day
  20. What is the AI for lineoleic acid for lactating women?
    13g/day for all age groups
  21. What type of fatty acid is linoleic acid?
  22. Why does lineoleic acid have an AI and how is it determined?
    Due to lack of evidence for determining the requirement during lactation, the AI is set based on the median lineoleic acid intake of lactating women where a deficiency is basically nonexistant in free-living populations
  23. How are n-3 FA secreted in milk during lactation?
    The demand for secretion of n-3 polyunsaturated fatty acids in milk during lactation must be met by n-3 fatty acids from maternal tissues or through dietary intake
  24. How are plasma and RBC lipid DHA levels affected during lactation?
    Lower plasma and red blood cell lipid DHA levels are present in lactating women compared to non-pregnant, non-lactating women
  25. How can DNA levels be increased in both the mother and newborn infant?
    Supplementation with fish oil
  26. Why do lactating women experience lower plasma and red blood cell lipid DHA levels?
    • May reflect declining DNA status due to inadequate n-3 FA intakes in the women in these studies
    • Changes in maternal DNA levels are normal physiological responses to the changes in endocrine status, lipoprotein and lipid metabolism, or nutrient transfer that accompany pregnancy and lactation
  27. What is the AI for alpha-linolenic acid during lactation and how is it determined?
    • 1.3g/day
    • Because of a lack of evidence for determining the requirement during lactation, the AI is set based on the median alpha-linolenic acid intake of lactating women where a deficiency is basically non-existent in free-living populations
  28. How can an n-3 deficiency be combated?
    Small amounts of EPA and DHA can contribute towards reversing an n-3 fatty acid deficiency and can therefore contribute towards the AI for alpha-linolenic acid
  29. How does the requirement for CHO change during lactation?
    The requirement for CHO increases during lactation
  30. Why are CHO requirements increased during pregnancy?
    • Higher respiratory quotient and rates of CHO utilization have been reported in lactating women compared with non-lactating women
    • Consistent with the preferential use of glucose by the mammary gland
  31. What is the lactose content of human milk?
  32. How is lactose synthesized?
    • Lactose is synthesized from glucose and so an increased supply of glucose must be obtained from ingested carbohydrates
    • Or via an increased supply of amino acids in order to prevent utilization of the lactating woman's endogenous proteins for glucose production
  33. How do maternal fat stores contribute to lactose formation?
    Glycerol derived from endogenous or exogenous fat may contribute to the increased production of glucose through gluconeogenesis.  However, the amount of fat that can be oxidized daily greatly limits the contribution of glycerol to glucose production and thus lactose fermentation
  34. What is the carbohydrate EAR for lactation?
  35. What is the carbohydrate RDA for lactation?
  36. How is the carbohydrate EAR during lactation set?
    Sum of the CHO intake necessary to replace the CHO secreted in human milk (60g/day) and the EAR for adolescent girls and women (100g/day)
  37. How is the carbohydrate RDA during lactation set?
    Set by using a CV of 15% based on the variation in brain glucose utilization
  38. What is the AI for fiber during lactation?
  39. Why is the AI for fiber the same for lactating and non-lactating women?
    There is no evidence to suggest that the beneficial effects of fiber in reducing the risk fo CHD in adolescent girls and women is different from non-pregnant adolescent girls and women
  40. Why are thiamin EAR levels increased during lactation?
    • For lactating women it is assumed that 0.16 mg of thiamin is transferred in their milk each day when daily milk production is 0.78L
    • An additional 0.1mg of thiamin is added to the EAR (0.9mg/day) for the nonpregnant, nonlactating women to cover the energy cost of milk production
  41. What is the EAR for thiamin change during lactation?
    EAR=0.9+0.16(in milk)+0.1(milk production)=1.2mg/day
  42. How efficient is riboflavin for milk production?
    Riboflavin for milk production by the mother is assumed to be 70% efficient
  43. What is the EAR for riboflavin for lactating women and how is it calculated?
    Ear is 0.9mg/day for nonpregnant and nonlactating women, 0.4mg/day is added, giving an EAR of 1.3mg/day
  44. How is the RDA for riboflavin set?
    • Assuming a CV of 10%
    • RDA=EAR+2CV
    • Therefor, for riboflavin the RDA is 120% of the EAR
    • 1.3x1.2=1.6mg/day
  45. How does the riboflavin vary if a women is breastfeeding more than one infant?
    Those breastfeeding more than one infant are likely to require more riboflavin
  46. How much niacin is secreted during lactation?
    An estimated 1,4mg of preformed niacin is secreted daily during lactation
  47. How much additional niacin is required during lactation?
    • 1.4mg/day is secreted during lactation
    • 1mg to cover energy expenditure involved in milk production
    • 2.4mg of additional NE (niacin equivalents) are required
  48. What is the EAR of niacin for non-pregnant, non-lactating women?
    11mg of NEs
  49. What is the EAR of niacin during lactation?
    11+2.4=13.4 (rounded down to 13)
  50. Why is the coefficient of variability so large for niacin?
    The wide variation in the efficiency f converting tryptophan to niacin
  51. What is the RDA for niacin during lactation?
    • CV of 15% is used
    • RDA=13.4*1.3=17mg/day of NEs
  52. How is the AI for biotin adjusted for lactating women?
    To cover the amount of biotin secreted in milk, the AI is increased by 5ug/day for lactating adolescents and women
  53. How do pantothenic acid levels in milk vary with pantothenic acid intake?
    Pantothenic acid content of milk appears to increase with increased intake of the vitamin
  54. What is the recommended AI for pantothenic acid during lactation?
    • 7mg/day
    • Based on 1.7mg/day are secreted in milk
    • Lower maternal blood concentrations when intakes are 5-6mg/day
  55. How much B6 does human milk contain?
  56. How much excess B6 must be consumed during lactation to ensure adequate B6 in milk?
    To ensure a milk B6 concentration of 0.13mg/L it is estimated that about 5 times that amout of B6 must be consumed in addition to the EAR of 1.1mg/day
  57. What is the EAR for vitamin B6 during lactation?
  58. How much folate is secreted in human milk?
    Estimated to be 85ug/L
  59. What must be taken into account when getting folate from a dietary source?
    The estimated 50% bioavailability of food folate
  60. How much extra folate is needed to cover lactation?
    0.78L (milk volume)x85ug/L(folate concentration)x2(bioavailability correction factor)=133ug/day
  61. What is the EAR of folate during lactation?
    320ug/day+133ug/day=453ug/day DFEs (rounded to 450)
  62. What is the RDA for folate during lactation?
    • Assume CV of 10%
    • RDA=450*1.2=540 (rounded to 500)
  63. How much B12 does human milk contain in the first 6 months?
  64. How much B12 does human milk contain during the second 6 months of lactation?
  65. What is the EAR for folate during lactation?
    0.33ug/day+2ug/day=2.4ug/day (rounded)
  66. What is the RDA for folate during pregnancy?
    • Assume CV of 10%
    • RDA=2.4*1.2=2.8ug/day
  67. When do low B12 concentrations in human milk commonly occur?
    • When the mother is a strict vegetarian
    • In developing countries where the usual consumption of animal products is low
  68. Why is the need for choline increased during lactation?
    A substantial amount of choline is secreted in human milk
  69. What is the average choline content of human milk?
  70. What is the increase of AI for choline during lactation?
    Increase in AI is 125mg/day, based on an assumption of 100% absorption efficiency
  71. How much vitamin C is produced in human milk?
  72. What is the EAR for vitamin C for lactation?
    • 14-18yrs=96mg/day
    • everyone else=100mg/day
  73. What is the RDA for vitamin C during lactation?
    • 14-18yrs=115mg/day
    • Everyone else=120mg/day
  74. How much vitamin A do milk-fed infants consume?
    400ug/day in the first 6 months of life
  75. What is the EAR for vitamin A during lactation?
    • 14-18yrs=885ug RAE/day
    • Everyone else=900ug RAE/day
  76. What is the RDA for vitamin A during lactation?
    • 14-18yrs=1200ug RAE/day
    • Everyone else=1300ug RAE/day
  77. How much vitamin D is secreted in human milk?
    Small quantities of maternal circulating vitamin D and its metabolites are secreted into human milk
  78. How much vitamin D is needed when sunlight exposure is inadequate?
    Based on observations in nonlactating women that when sunlight exposure is inadequate, an RDA of 15ug/day is needed
  79. How much a-tocopherol is secreted daily in human milk?
    4mg/day within the first 6 months of life
  80. What is the EAR od vitamin E for lactating women?
  81. Are vitamin E supplements necessary during lactation?
    No. Because lactating women are likely consuming more vitamin E than reported and vitamin E deficiency in infants receiving human milk is extremely rare
  82. What is the RDA for vitamin E during pregnancy?
  83. Why is vitamin K intake not adjusted for lactation?
    Vitamin K is not significantly secreted in milk, there is no need to change the intake.
  84. What is the AI for non-pregnant, pregnant, and lactating women?
    • 75ug/day <18
    • 90ug/day 18 years and older
  85. Does the AI for total water change during lactation?
    No. It is set based on median total water intakes during lactation
  86. Why do water requirements change during lactation?
    • There is no evidence to suggest that renal function and hydration status are different during lactation
    • However, more water is needed to account for the milk being secreted
  87. What is the AI for water during lactation?
  88. What is the potassium content in human milk?
    The potassium content in human milk averages around 0.4g/day during the first 6 months of lactation
  89. SLIDE 61!!!!!!!!!!!!!!