NUTR 337-4

Milk energy output is computed from milk production and the energy density of human milk

The stage and extent of breastfeeding affect the incremental energy requirements for lactation

In general, during the first 6 months postpartum well-nourished lactating women experience a mild, gradual weight loss, averaging 0.8kg/mo

• 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

• 0.78L/day in term infants from birth through 6 months
• 0.6L/day in term infants from 7-12 months of age

EER=Adult/adolescent EER (depending on age)+milk energy output-weight loss

No. The concentration of protein in human milk is not influenced by diet or body composition even in undernourished 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

• 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

• 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

Urea

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

• 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

1.05g/kg/day or +21g/day additional protein

0.66g/kg/day

1.05g/kg/day

0.80g/kg/day

1.1g/kg/day

• 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

13g/day for all age groups

N-6

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

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

Lower plasma and red blood cell lipid DHA levels are present in lactating women compared to non-pregnant, non-lactating women

Supplementation with fish oil

• 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

• 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

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

The requirement for CHO increases during lactation

• 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

74g/L

• 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

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

160g/day

210g/day

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)

Set by using a CV of 15% based on the variation in brain glucose utilization

29g/day

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

• 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

EAR=0.9+0.16(in milk)+0.1(milk production)=1.2mg/day

Riboflavin for milk production by the mother is assumed to be 70% efficient

Ear is 0.9mg/day for nonpregnant and nonlactating women, 0.4mg/day is added, giving an EAR of 1.3mg/day

• Assuming a CV of 10%
• RDA=EAR+2CV
• Therefor, for riboflavin the RDA is 120% of the EAR
• 1.3x1.2=1.6mg/day

Those breastfeeding more than one infant are likely to require more riboflavin

An estimated 1,4mg of preformed niacin is secreted daily 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

11mg of NEs

11+2.4=13.4 (rounded down to 13)

The wide variation in the efficiency f converting tryptophan to niacin

• CV of 15% is used
• RDA=13.4*1.3=17mg/day of NEs

To cover the amount of biotin secreted in milk, the AI is increased by 5ug/day for lactating adolescents and women

Pantothenic acid content of milk appears to increase with increased intake of the vitamin

• 7mg/day
• Based on 1.7mg/day are secreted in milk
• Lower maternal blood concentrations when intakes are 5-6mg/day

0.13mg/L

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

0.6+1.1=1.7mg/day

Estimated to be 85ug/L

The estimated 50% bioavailability of food folate

0.78L (milk volume)x85ug/L(folate concentration)x2(bioavailability correction factor)=133ug/day

320ug/day+133ug/day=453ug/day DFEs (rounded to 450)

• Assume CV of 10%
• RDA=450*1.2=540 (rounded to 500)

0.33ug/day

0.35ug/day

0.33ug/day+2ug/day=2.4ug/day (rounded)

• Assume CV of 10%
• RDA=2.4*1.2=2.8ug/day

• When the mother is a strict vegetarian
• In developing countries where the usual consumption of animal products is low

A substantial amount of choline is secreted in human milk

156mg/L

Increase in AI is 125mg/day, based on an assumption of 100% absorption efficiency

40mg/day

• 14-18yrs=96mg/day
• everyone else=100mg/day

• 14-18yrs=115mg/day
• Everyone else=120mg/day

400ug/day in the first 6 months of life

• 14-18yrs=885ug RAE/day
• Everyone else=900ug RAE/day

• 14-18yrs=1200ug RAE/day
• Everyone else=1300ug RAE/day

Small quantities of maternal circulating vitamin D and its metabolites are secreted into human milk

Based on observations in nonlactating women that when sunlight exposure is inadequate, an RDA of 15ug/day is needed

4mg/day within the first 6 months of life

16mg/day

No. Because lactating women are likely consuming more vitamin E than reported and vitamin E deficiency in infants receiving human milk is extremely rare

15mg/day

Vitamin K is not significantly secreted in milk, there is no need to change the intake.

• 75ug/day <18
• 90ug/day 18 years and older

No. It is set based on median total water intakes 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

3.8L/day

The potassium content in human milk averages around 0.4g/day during the first 6 months of lactation