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How is milk energy output computed?
from milk production and the energy density of human milk
What affects the incremental energy requirements for lactation?
the stage and extent of breastfeeding
How are milk production rate affected by time?
- milk production increases during the first 6 months of full lactation
- beyond 6 months postpartum, typical milk production rates are variable and depend on weaning
How could the energy cost of lactation be met without increasing food intake?
by reducing the time spent in physical activity or an increase in the efficiency of preforming routine tasks
What are the activity patterns of lactating women?
- a decrease in moderate and discretionary activities appears to occur in most lactating women in the early post partum period
- activity patterns beyond this period are highly variable
Since no adaptation in basal metabolism and physical activity have been observed how are energy requirements for lactation met?
energy requirements are partially met by mobilization of tissue stores BUT primarily from diet
Changes in adipose tissue volume has been measured, in the first 6 months postpartum which region accounts for the reduction in adipose tissue volume?
subcutaneous decreased from 23.2 L to 20.0 L
What happens to non-subcutaneous adipose tissue volume 1st 6 months postpartum?
non-subcutaneous adipose tissue volume actually increased
What is the mean milk production rates of American women for the first six months postpartum?
What is the mean milk production rates of American women with term infants 7 to 12 months of age?
For calculation a value of _____ kcal/g milk has been used.
The milk energy output for the 1st 6 months of lactation is ___________
The milk energy output for the 2nd 6 months of lactation is __________
What equation is used to calculate the EER for lactation for 14-18 y.o. for the 1st six months of lactation.
EER= Adolescent EER + 500 – 170 (Milk Energy Output – Weight Loss)
What equation is used to calculate the EER for lactation for 14-18 y.o. for the 2nd six months of lactation.
EER = Adolescent EER + 400 – 0(Milk energy output – Weight loss)
What equation is used to calculate the EER for lactation for 19- 50 y.o. for the 1st six months of lactation.
EER = Adult EER + 500 – 170(Milk energy output – Weight loss)
What equation is used to calculate the EER for lactation for 19- 50 y.o. for the 2nd six months of lactation.
EER= Adult EER + 400 – 0 (Milk energy out put – Weight loss)
What is the derivation of the EER for lactating women based on?
- EER for normal weight adult women using current age, weight, and PAL
- milk energy output
- energy mobilization from tissue stores
What weight loss is experienced in the first 6 months postpartum by well nourished lactating women?
Does dietary protein intake or bod protein content influence the concentration of protein in human milk?
- not even in under nourished mothers
What amount of protein should be consumed by lactating women to maintain good milk production and conservation of skeletal muscles?
1g/kg body weight/day
What approach is used to determine the protein requirement during pregnancy?
the factorial approach
T or F
it is assumed that the process of lactation alters the maintenance protein requirement
T or F
It is assumed that protein and/or amino acid requirement is increased in proportion to milk production
Human milk is characterized by relatively high concentrations of NPN substances. What precent of total milk Nitrogen do they contribute?
20 - 27%
What is the quantitatively important NPN component of milk?
Where do the increased N needs of lactating women to produce milk NPN come from?
What factor is used to convert NPN to protein?
- same factor used to convert N to protein
How is the additional protein requirement for lactation defined?
as the output of total protein and NPN in milk
the factorial estimate of the increase in protein requirement associated with lactation assumes that the incremental efficiency on N utilization as ______ in adults and adolescents is the same as for non-lactating women and adolescents
It is assumed that the cost of making protein for maintenance requirements is the same as that for ______________________
growth and lactation
The values for various months of lactation were averaged to set the amount by which the protein EAR should be increased by. How much more protein should lactating women consume?
How many g/ kg of body weight should be consumed daily by lactating women?\
How is value determined?
- 1.05 g/kg/day
- EAR= 0.66 g/kg/ day of protein for non-lactating 57 kg women)
- requirements for protein loss during lactation 21.2 g/day ÷ 57 kg (reference women) = +0.39 g protein/kg/day
- EAR for lactating women 0.66 + 0.39 = 1/05 g protein/ kg/ day
What is the RDA for protein during lactation?
- 1.1 g/kg/day
- +25 g/day of additional protein
What is the AI for lactating females b/w 14-50 for n-6 FA (linoleic acid)
Why is the AI for linoleic acid based on the median intake of lactating women where a deficiency is basically nonxistent in free-living populations?
- b/c of a lack of evidence for determining the requirement during lactation
- no evidence that maternal dietary intervention witn n-6 FAs has any effect on infant growth and development.
How must the demand for secretion of n-3 PUFAs in milk during lactation be met?
by n-3 FAs from maternal tissues OR through dietary intake
What do lower plasma or RBC lipid DHA levels present in lactating women compared to non-lactating women reflect?
- declining DHA status due to inadequate n-3 FA intakes in the women in these studies
- change in maternal DHA levels are normal physiological responses to the changes in endocrine status, lipoprotein, and lipid metabolism, or nutrient transfer that accompany pregnancy and lactation
What are the effects of supplementation with fish oil during pregnancy and lactation?
- pregnancy: increase in DHA in both mother and newborn infant
- lactation: increase in the [DHA] in mothers milk and in infants blood
- evidence is not available to show that increasing intakes of DHA in pregnant and lactating women consuming diets that meet requirements for n-6 and n-3 FAs have any physiologically significant benefit to the infant
What is the AI for n-3 FAs (α-linolenic acid) for lactating women between 14 and 50?
Other then α-linolenic acid what FAs can contribute towards the n-3 FA AI and why?
- EPA and DHA
- they contribute towards reversing an n-3 FA deficiency and thus contribute towards AI for α-linolenic acid
Why is an AI set for α-linolenic acid? How is it set?
- lack of evidence for determining the requirement during lactation
- set based on the median α-linolenic acid intake of lactating women where a deficiency is basically non-existant in free-living populations
T or F
CHO requirement is increased during lactaiton
Higher ___________________ and rate of CHO utilization have been observed in lactating women compared to non-lactating women. This observation is consistent with the preferntial use of _____________ by the mammary gland.
- respiratory quotient (RQ)
The lactose content of human milk is approximately _______ and this concentration changes very little during the nursing period.
The amount of ______________ necessary for lactose synthesis must increase.
Lactose is synthesized form ____________.
How is the need for an increased supply of glucose met?
- from ingested CHO
- OR via increased supply of aa in order to prevent utilization of lactating women's endogenous proteins for glucose production
- glycerol derived from endogenous 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
What is the EAR and RDA for CHO for lactation for women 14-50?
- EAR 160 g/day
- RDA 210 g/day
What is the CV for CHO and what is it based on?
15% based on the variation in brain glucose utilization
How many g CHO/day are needed for lactating women in addition to the EAR for CHO to replace the CHO secreted in human milk?
The RDA for CHO in lactating women is ______% the EAR.
How is the AI for fiber set?
14g/1000 kcal • median energy intake each age and gender group
What is the AI for fiber in lactating women? Is the AI different form non-lactating women?
- 29 g/day
- yes but it is only increased by an increase by the in median energy intake as there is no evidence to indicate beneficial effects of increasing fiber in reducing the risk of CHD is different from non pregnant women
How much thiamine is added to the non-pregnant / non-lactating EAR of 0.9 mg/day? Why?
- + 0.1 mg to cover energy cost of milk production and
- + 0.16 mg of thiamine is transferred in their milk each day when daily milk production is 0.78 L
What is the EAR and RDA for thiamine?
- EAR 1.2 mg/day
- RDA 1.4 mg/day
- RDA = 120% EAR
How many mg of Riboflavin is transferred to milk each day when daily milk production is 0.78 L?
What is Riboflavin's EAR for non-lactating women? What is the EAR for lactating women? Why?
- non-lactating 0.9 mg/day
- lactating 1.3 mg/day
- +0.4 mg/day b/c use of riboflavin for milk production by the mother is assumed to be 70% efficient thus the value is adjusted upward to 0.4 mg/day for the amount of the vitamin that should be replaced
What is the RDA for Riboflavin in lactating women? How is it set?
- 1.6 mg/day
- set by assuming a CV of 10%
How much performed niacin is secreted daily during lactation? What is the total amount of Niacin added to the EAR for lactating women?
- 1.4 mg of preformed niacin is secreted daily during lactation
- 1 mg added to cover energy expenditure involved in milk produciton
- = +2.4 mg
- EAR = 13.4 --> rounded down to 13 mg
What is the CV for Niacin? Why? What is the RDA?
- wide variation due to the efficiency in converting tryptophan to niacin may contribute to the large apparent variation
- 17 mg/day
How much is the AI for biotin increased by for lactating women (14-50 yo)?
How does pantothenic acid intake affect its concentration in milk?
increased pantothenic acid intake leads to an increased content in milk
Does lactation affect blood pantothenic acid levels in lactating women?
- blood pantothenic acid levels are lower in lactating women at 3 months and 6 weeks postpartum than for non-pregnant women
If there is no evidence that pantothenic acid intakes are inadequate to support function during lactation why is the AI set at 7 mg/day
- on the basis of the additional secretion of the vitamin in human milk (1.7 mg/day)
- lower maternal blood concentration reported when intakes are about 5 to 6 mg/day
Why is the additional requirement for B6 during lactation considerably in excess of that suggested by the amount secreted via lactation?
to ensure a milk B6 [0.13 mg/L] it is estimated that about 5x that amount (0.6 mg) of B6 must be consumed in addition to the EAR of 1.1 mg/day
What is the EAR for B6 in lactating women? What is the RDA?
- 1.7 mg/day
- 2.0 mg/day
- RDA = 120% EAR
what is the average daily amount fo folate secreted in human milk? What must the dietary intake needed to provide this amount account for?
- 85 ug/L
- must account for the estimated 50% bioavailability of food folate
What is the calculation used to obtain the extra amount of Folate needed to cover lactation?
- Milk volume x folate concentration x bioavailability
- 0.78 L x 85 ug/L x 2 = 133 ug/day
What is the EAR for Folate in lactating women? What is the RDA in lactating women?
- EAR of 450 ug/day of DFE
- RDA 500 ug/day
- RDA= 120% EAR
What is the average amount if B12 secreted into the milk of mothers with adequate B12 status during the first 6 months of lactation?
What is the average amount if B12 secreted into the milk of mothers with adequate B12 status during the second 6 months of lactation?
What is the B12 EAR for lactating women? What is the B12 RDA for lactation women?
- EAR 2.4 ug/day
- RDA 2.8 ug/day
- RDA = 120% EAR
What situations can result in low B12 concentrations in human milk?
- when the mother is a strict vegetarian
- in developing countries where the usual consumption od animal products is low
Why is the need for choline likely to be increased during lactation?
- a substantial amount of choline is secreted in human milk
- mechanisms for conserving maternal choline status have not been identified
For the assumption of an average milk volume production of 0.78 L/ day and an average choline content of milk of _________
What does the AI increase by? What assumption is this based on?
- 125 mg/day
- based on the assumption of 100% absorption efficiency
What is used to estimate the EAR for Vit C during lactation?
- the average Vit C produced in milk during the 1st 6 months of lactation is added to the EAR
- + 40 mg/day
What is Vit C EAR for lactation for 14- 18 yo? What is Vit C RDA for lactation for 14- 18 yo?
- EAR 96 mg/day
- RDA 115 mg/day
- RDA = 120% EAR
What is Vit C EAR for lactation for 19- 50 yo? What is Vit C RDA for lactation for 19- 50 yo?
- EAR 100 mg/day
- RDA 120 mg/day
- RDA = 120% EAR
Does the EAR for Vit C decrease for longer periods of lactation?
- the Vit C content of human milk declines with length of lactation
- milk volume declines with the addition of solid foods
- the EAR is not decreased
How much Vit A is goes to milk in lactating women in 2st 6 months postpartum?
What is the Vit A EAR for lactating girls 14-18 yo? What is the Vit A RDA for lactating girls 14 - 18 yo?
- EAR 885 ug RAE/day
- RDA 1200 ug RAE/day
- RDA = 140% EAR
- The calculated values for RDA have been rounded to the nearest 100 ug
What is the Vit A EAR for lactating women 19- 50 yo? What is the RDA for lactating women 19- 50 yo?
- EAR 900 ug RAE / day
- RDA 1300 ug RAE/day
- RDA= 140% EAR
- The calculated values for RDA have been rounded to the nearest 100 ug
Do the Vit D requirements change during lactation? Why?
- small quantities of maternal circulating vit D and its metabolites are secreted into human milk
- minimum vit D intake to sustain serum 25(OH)D concentration in th normal range during lactation is unclear
- there is no evidence that lactation increases a mothers RDA for vit D
How much Vit D is needed when sunlight exposure is inadequate?
RDA 15.0 ug (600 IU)/ day
What is the estimated average amount of α-tocopherol(vit E) secreted into human milk in the 1st 6 months of lactation?
What is EAR of α-tocopherol in lactating women? What is the reported median intake of α-tocopherol in lactating women?
Estimates of vit E intake are underreported and vit E deficiency in infants receiving humans milk is extremely rare what does this indicate?
lactating women are likely consuming more vit E than reported and that ingestion of supplements is unnecessary during lactation
What is the α-tocopherol RDA in lactating women?
- 15 mg/day
- RDA = 120% EAR
- the calculated RDA in mg is rounded down
What are the effects of increasing Vit K in lactating women? How does this influence the AI? What is the AI?
- phylloquinone content in maternal milk increased after treatment of mothers with pharmacological doses of vit K
- however vit K content of milk is little affected by intake of lactating mothers who consume typical diets
- b/c vit K is not significantly secreted in milk, there is no evidence to suggest that AI for lactating women should be different form that of non-lactating women
- AI 75 ug/day <18 yo
- AI 95 ug/day >18 yo
What are water requirements during lactation set based on?
- there is no evidence suggesting that renal function and hydration status are different during lactation
- therefore the AI for total water (drinking water, beverages, and food) is set based on median total water intakes during lactation
What is water AI for lactating women?
- AI 3.8 L/day
- appox. 3.1 L as total beverages (drinking water)
The potassium content in human milk averages around _____ during the first 6 months of lactation. The efficiency to convert dietary potassium to milk is _____. Therefore the AI for potassium during lactation is set ______.
- 0.4 g/day
- 5.1 g/day (4.7 g + 0.4 g)
A small amount of sodium is secreted daily in human milk during the first 6 months of lactation ______________. Therefore the AI for sodium for lactating women is set___________ ______________________.
- 0.12 g/day [5.2 mmol/day]
- to be equal to that of non-lactating, young women
The AI for Chloride is set at an equimolar amount based on the AI for __________.
What is the AI for sodium for lactation?
AI 1.5 g (65 mmol)/day of sodium
What is the AI for chloride for lactation?
AI 2.3 g (65 mmol)/ day of chloride
What is the primary source of calcium secreted in human milk?
- maternal bone resorption
- the increase of resorption is independent of Ca intake
- the bone loss observed during lactation appears to be regained upon return of ovarian function
The source of calcium utilized by a lactating women for milk production could be from?
- higher dietary intake
- increased fractional intestinal absorption
- reduced renal excretion
- stimulation of bone resorption***
How much calcium is used in milk production daily?
Most studies have found ______________ in blood 1,25(OH)2D concentrations b/w lactating and non-lactating women
Is calcium absorption increased during lactation?
No, Ca abs. is not increased even in women consuming a relatively low Ca diet
What does change with regards to Ca in the body during lactation?
- increased renal conservation of Ca occurs during lactation
- both the increased mobilization of Ca stores and decreased urinary calcium excretion are sufficient to provide calcium for milk production.
what are the changes in bone mass that occur during lactation related to? What are the long term effects of these changes in bone mass?
- lack of estrogen rather than to the increased demand of calcium for milk production
- no association b/w previous lactation history and bone mass density or fracture risk
What are the Ca AI for lactating women?
- the same as non lactating women
- <18 yo AI 1300 mg/day
- >18 yo AI 1000 mg/day
What are the concentrations of Phosphorus in human milk?
- range from approximately 12.1 to 15.8 mg/dL
- decrease as lactation progesses
Assuming a milk production of 780 mL/day how much Phosphorus would a lactating women lose?
90 to 120 mg/day
How does the loss of phosphorus affect blood levels?
- blood levels in lactating women are in the high-normal to above normal range
- hight in lactating women then non-lactating women
What factors are related to high blood phosphorus levels?
- due to fall in blood parathyroid hormone which leads to high serum Pi
- increase in bone resoprtion
In regards to phosphorus metabolism in lactating women what occurs independently of dietary phosphorus intake to provide necessary phosphorus for milk production?
- increased bone resorption
- decreased urinary excretion of phosphorus
What is the RDA for phosphorus in lactating women?
- no evidence supports that phosphorus requirements are increased during lactation
- same as non-lactating
- <18 years 1250 mg/day
- >18 years 700 mg/day
what is the concentration of Magnesium in human milk? Is it influenced by mothers Mg intake?
Assuming milk production of 780 mL/day how much Mg is secreted into milk?
9 - 26 mg/day
How do the milk, blood and erthyrocyte Mg levels change in lactation?
- milk concentration do not change throughout lactation
- blood and erthyrocyte Mg levels do not differ b/w lactating and non-lactating women at daily Mg intakes
What are daily Mg intakes?
How may the Mg necessary for milk production provided?
- decreased urinary excretion
- increased bone resportion
How are the median Iron needs durin lactation estimated?
sum of iron secretion in human milk and basal iron losses calculated for nonpregnant, nonlactating women (0.896 mg/day)
WHat is the derived estimate of iron secreted in human milk?
- 0.27 mg/day
- 0.35 mg/L x 0.78 L/day
What is the median total requirement for absorbed iron?
- 1.17 mg/day
- 0.896 mg/day + 0.27 mg/day
What % of iron consumed is absorbed?
What is the EAR and RDA for Iron in lactating women over 18?
- EAR 6.5 mg
- RDA 9 mg/day
- RDA = 160% EAR
- CV= 30%
What adjustments must be made for adolescent lactating mothers?
- provision made for deposition of iron in tissues (0.001mg/day)
- hemoglobin mass (0.14 mg/day) as part of expected growth of the mother
What is the median requirement for abs. Fe, RDA and EAR for lactating adolescent mothers?
- median requirement for abs. iron = 1.26mg/day (0.85 + 0.27 + 0.001+ 0.14)
- EAR = 7 mg/day
- RDA= 10 mg/day
- CV= 30%
What is the effect on Zinc of postpartum involution of the uterus and decreased maternal blood volume?
- appx. 30 mg of zinc will be released that have accumulated during pregnancy
- an avg. of appx. 1 mg/day for 1st month post partum
- endogenous zinc is available for reutilization during lactation
- thus 1 mg/day can be subtracted form the amount of Zn lost the 1st 4 weeks of lactation
What is the avg. calculated increased requirement of zinc during lactation?
what is the reported values for fractional abs. of zinc for adult women? What is the fractional abs. of zinc in lactating women?
What is the additional zinc requirement during lactation?
what is the EAR for Zn in lactating women?
- <18 yo EAR = 10.9 mg/day
- >18 yo EAR = 10.4 mg/day
What is the RDA for Zn in lactating women?
- <18 yo RDA= 13 mg/day of Zn
- >18 yo RDA= 12 mg/day of Zn
- CV= 10%
What is the EAR for Iodine in lactating women based on?
- average requirements =95 ig/day
- average daily loss of iodine in human milk ~114 ug/day
What is the EAR for iodine in lactating women?
What is the RDA for iodine in lactating women?
What is human milk Selenium concentration?
What is the average amount of selenium secreted in milk in the first 2-6 months of lactation?
What form is most selenium present in human milk in?
- has a greater bioavailability
- greater than 90%
- thus her is no adjustment made for absorption
What is the RDA for selenium in lactating women?
what is the average amount of Cu secreted in human milk?
what is the bioavailability of an adult consuming the EAR f copper?
Due to bioavailability how much copper must be consumed to replace the copper secreted in human milk?
What is the EAR for copper in lactating women?
- <18 yo EAR = 985 ug/day
- >18 yo EAR = 1000 ug/day
What is the RDA for Copper in lactating women?
- RDA = 1300 ug/day
- CV= 15%
How much Manganese is secreted in human milk?
What is the AI of Manganese for lactating women? why?
- 2.6 mg/day
- the req. during lactation does not appear to be greater than the requirement for non-lactating women
- b/c manganese deficiency has not been observed in North American lactating women the AI is based on the median intake
Does Floride consumption affect infant and maternal floride levels? What is the AI?
- No floride supplementation during lactation does not affect fluoride intakes by the nursing infant or the floride requirements of the mother
- AI = 3 mg/day
- not increased as floride concentrations in human milk are very low and insensitive to differences in maternal [Floride]
How is the AI for chromium different during lactation?
- 0.2 ug/day lost to milk
- only 1% is abs. thus 20 ug/day is added to the AI
How much molybdenum is excreted in milk daily?
What is the EAR for molybdenum in lactating women? What is the RDA?
- EAR = 35 to 36 ug/day
- RDA = 50 ug/day