Breast milk composition Flashcards

1
Q

In what form are lipids found in milk, in terms of structure? What is the location of different lipids?

A

in membrane bound micelles (globules)

membrane: PL, C (also proteins)
core: TG

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2
Q

Carbs can be converted to what types of fatty acids? What cells do this, to add to breast milk?

A

non essential FA (16C or less)

alveolar cells

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3
Q

total fat in milk is about ___%

A

3-5.5%

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4
Q

What type of diet is a baby on? Why is this necessary (3)?

A

high fat diet

fat is ENERGY DENSE - baby has small stomach but high energy needs for growth

more efficient for FAT DEPOSITION in young infant (costs less energy than protein or carb conversion to fat)

high requirement for EFA, especially long chain

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5
Q

What types of lipids are in milk? What is the main type?

A
98% is triglycerides
also:
FFA
MAG
DAG
cholesterol + CE
PL
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6
Q

What is the importance of TGs in milk?

A

dense energy source

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7
Q

What are the products of lipolysis?

A

1 MAG

2 FFA

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8
Q

What hormone stimulates milk lipid production? What are its effects (2)?

A

prolactin

increase in mammary gland LPL (lipoprotein lipase) activity (increase uptake of FFA into mammary gland)

decrease in adipose LPL activity

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9
Q

Which position on a TG is resistant to lipolysis?

A

position 2 (middle)

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10
Q

how does human milk differ from bovine in terms of TG composition?

A

more PALMITATE on position 2 of TGs

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11
Q

Describe the role of LPL on milk production:

A

LPL hydrolyze TG from lipoproteins (unloads FFAs)
mammary gland LPL activity increases, while adipose LPL decreases

so: fat is preferentially unloaded to mammary glands rather than maternal fat stores

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12
Q

Where do milk lipids come from? (2)

A

16C or less: synth from carbohydrates by alveolar cells

18C or more: from maternal stores or diet

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13
Q

The primary saturated fat in milk is _____

A

palmitic acid

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14
Q

What are the advantages of having more palmitate in position 2? (4)

A

less cleavage by lipases:

  • MAG palmitate is better absorbed than FFA palmitate
  • forms better micelles
  • prevent FFA palmitate from binding with Ca or Mg (form soaps) and decreasing absorption
  • MAG palmitate possibly help with intestinal microbiome
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15
Q

What enzymes facilitate the digestion of lipids in the infant (4)?
What enzyme is only produced in tiny amounts, and why?

A

gastric lipase
Bile-salt stimulated lipase (from milk)
LPL
pancreatic-like lipases

Pancreatic lipase; pancreas not yet mature enough to function fully

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16
Q

compared to cow milk, human milk has (more/less) saturated fat, and more ____ acid. What are the implications of this?

A

less saturated fat
more oleic acid

oleic acid is more easily absorbed

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17
Q

List in order of increasing EFA content:

fortified formula, cow milk, breast milk

A

cow < breast < fortified formula

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18
Q

Even though formula can have more EFAs, why might breast milk still be better in meeting the infants essential lipids requirements?

A

enzymes for conversion of EFAs into other PUFAs is not yet mature!
better to obtain some DHA and arachidonic acid from diet since cannot synthesize well
(breast milk is better source of PUFAs)

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19
Q

What lipids require fewer bile salts to emulsify? why?

A

short chain FA (less hydrophobic)
MUFA (lower melt point)
PUFA (lower melt point)

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20
Q

Why is DHA important?

How can the mother increase DHA content in milk?

A

retinal PL, membranes for brain!
(proper vision + brain dev)
more fatty fish in diet

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21
Q

true/False: formula fed infants will have lower arachidonic acid concentration in brains

A

false; brain not affected

but plasma conc is lower!

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22
Q

What enzyme types are needed for converting EFAs into other PUFAs?

A

elongases and desaturases

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23
Q

What is the main component of milk (after water) and the least variable (constant %)?

A

lactose

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24
Q

the osmolality of milk is identical to ____. Why is this important?

A

plasma

lowers energy cost of making milk; otherwise would need to expend energy to maintain osmotic gradient

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25
Q

What are some advantages of human vs cow milk in terms of minerals? (3)

A
  • better absorbed due to proteins and enzymes in milk
  • higher Ca:P ratio
  • lower solute load (less Na, K, Mg, citrate) -> less kidney strain
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26
Q

what are the roles of lactose in milk? (4)

A
  • provide carbohydrate in diet
  • maintain milk osmolality
  • aids in absorption of minerals (chelates and solubilizes)
  • help lactobacilli (gut bacteria)
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27
Q

what proteins in breast milk aid Fe absorption?

A

Lactoferrin, xanthine oxidase

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28
Q

Glutathione PO aids in absorption of:

A

Se

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29
Q

What proteins in breast milk aid in Zn absorption?

A

Lactalbumin, alkaline phosphatase

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30
Q

Lactalbumin aids in absorption of ___ and ___.

A

Ca, Zn

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31
Q

What protein in breast milk aids in absorption of Mo?

A

xanthine oxidase

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32
Q

_____ in breast milk aids in absorption of Zn and ___.

A

alkaline phosphatase

Mg

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33
Q

What enzyme is present in breast milk, that could help with lactose digestion?

A

amylase (stable to digestion) -> aids in breaking down lactose

34
Q

What are the major factors that affect milk composition? (3)

A

gestational age
malnutrition
maternal body fat content

35
Q

True/False: preterm milk has higher levels of Ca, Mg, P, and vitamin D to match the preterm baby’s needs.

A

False; has similar content to mature milk.

This is insufficient for the needs of the preterm infant, so supplementation may be required

36
Q

As length of lactation increases, how does composition change (what increases, what decreases?)

A

decrease: protein, Ig, fat soluble vitamins
increase: fat, lactose, water soluble vitamins, energy

37
Q

How is the fatty acid composition different in colostrum vs mature milk?

A

colostrum: higher DHA for nerve cell division
mature: less DHA, more medium chain FA (12C, 14C, omega 6) - for increased myelination (used to form sheath)

38
Q

How is preterm milk different from mature milk, and why?

A

composition: more energy/protein/NaCl
less lactose

extra nutrition support is needed for fast growth, to make up for lost growth time inside uterus

39
Q

What effect does malnutrition have on breast milk immune factors?

A

Colostrum: less immune factors

Mature milk: no impact

40
Q

How does fore and hind milk differ?

A

fore milk: beginning of feeding period, higher in lactose and water

hind milk: at end of feeding period, higher in fat (3x)

41
Q

Frequent short feedings by the infant is known as ____ ____, and indicates what?

A

cluster feedings
growth spurt
(trying to stimulate more milk production)

42
Q

Can the mother alter her diet to change the total fat or volume of milk?

A

No; diet does not effect total fat/volume;

except SEVERE ENERGY RESTRICTION -> reduced volume

43
Q

True/False: cholesterol content in milk will depend on maternal diet

A

False; diet has no effect on PL or C content

only severe HYPERCHOLESTEROLEMIA will increase C content in milk

44
Q

What factor will change the fat content in breast milk?

A

Maternal fat stores
higher fat stores -> higher fat in milk
insufficient fat gain during pregnancy -> lower fat in milk

45
Q

what about milk fat can be altered by maternal diet?

A

exact fat composition

46
Q

What could cause a decrease in protein content in the mother’s breast milk?

A

prolonged protein-calorie malnutrition

47
Q

Is a low fat diet recommended during lactation? What effects does it have on milk and why (2)?

A

No;
will increase long chain saturated FA content because maternal stores are used to supply fat for milk, since diet is insufficient

decreased levels of EFAs - risk of deficiency

48
Q

Are the fat soluble vitamins in milk affected by maternal diet?

A

No; except VITAMIN D (will decrease if mother’s intake is low)

49
Q

Vegetarian mothers will produce milk with higher proportions of what fatty acid? Why?

A
omega 6 (linoleic)
higher proportion in plant fats
50
Q

How much of the milk fat is derived from maternal diet? What is diet is insufficient?

A

30%

draw from maternal stores

51
Q

____ soluble vitamins are affected by maternal malnutrition.

A

water

52
Q

Why can vitamin D supplementation be risky? What is the best method of supplementation?

A

low UL - risk of overdose and toxicity in infant (misread label)
400IU directly given to infant (if taken by mother, require much higher amount)

53
Q

infants of vegetarian mothers may have a deficiency in vitamin ____.

A

B12

54
Q

A deficiency in B6 in milk is caused by what? What are the symptoms in the infant?

A

maternal deficiency

lack of attentiveness

55
Q

How could a mother pass Beri-Beri on to her infant?

A

beri-beri is deficiency in B1 - levels in mother’s milk will be low, so baby will also have deficiency

56
Q

What are the negative consequences if breastfeeding as the only food source is continued beyond 6 months? (3)

A

Aversion to trying food
growth rate slows
iron deficiency

57
Q

What vitamins and minerals in milk depend on maternal status?

A

vitamins B1, B6, B12, C, D

minerals: Se, I

58
Q

True/False: human milk has more vitamin K than cow milk

A

False

59
Q

What are the general disadvantages of breastfeeding? (7)

A
  • can lead to deficiencies (D, low levels of K, Fe if prolonged past 6 months)
  • can pass on harmful compounds: drugs or env contaminants
  • transmit HIV
  • Incompatible with some metabolic disorders (PKU, galactosemia)
  • breastmilk jaundice
  • may cause eczema
  • not sufficient for premature infants (require fortification)
60
Q

How can environmental toxins affect nutritional status in the newborn? What is this disease called?

A

PCBs and dioxins interfere with vit K metabolism; induce cytochromeP450 in electron transport chain, uses up vitamin K (metabolized and excreted) instead of recycled

causes late hemorrhagic disease of the newborn

61
Q

when are PCBs and dioxins highest in milk, and where do they come from?

A

1st week after birth

from maternal fat stores (only 14% from diet)

62
Q

A medical drug that is safe to use during breastfeeding should: (2)

A

no be readily excreted into milk

have short half-life

63
Q

what are 4 factors that contribute to vit K deficiency and hemorrhagic disease in the newborn? What is done to prevent this?

A
  • low levels in milk
  • low stores in infant
  • cannot synthesize prothrombin well
  • sterile gut, cannot produce own vitamin K

newborns given vitamin K shot at birth

64
Q

Vitamin K is a substrate for what enzyme in cytochrome P450?

A

gamma-glutinyl carboxylase

65
Q

If the mother takes anticonvulsants, the baby will require:

A

vitamin K supplements

66
Q

What effects can antibiotics in milk have on the baby?

A

vomiting, allergy, sleepy, refuse to eat

67
Q

What are the effects of oral contraceptives on lactation? What is an alternative?

A

suppresses lactation
can cause breast growth in baby (gynecomastia)

mini-pill (progesterone only)

68
Q

What are the effects of alcohol or smoking on lactation and the infant?

A

both decrease milk production

alcohol will decrease infant intake
smoking increases risk of SIDS, less wt gain

69
Q

What is PKU, and what is required for infants with this condition?

A

inborn error of metabolism, cannot convert Phe -> Tyr
need low Phe formula (lofenac) otherwise Phe will build up and cause neurological damage
(infants screened at birth)

70
Q

What could happen if mothers eat a lot of garlic or spices during lactation?

A

changes taste of milk - can cause distress in baby

71
Q

What are the effects of caffeine or sedatives during lactation?

A

caffeine: restless irritable baby
sedatives: lethargic baby

72
Q

what is galactosemia?

What enzyme is deficient, and what are the consequences?

A

inborn error of metabolism (autosomal recessive)
deficient in 1-P-URIDYL TRANSFERASE
cannot convert galactose to UDP-galactose

so: Gal-1P will accumulate, and becomes GALACTITOL (toxic)

73
Q

What are the consequences of galactitol excess? (3)

A

cataracts
liver damage
severe mental retardation

74
Q

Describe the catabolism of galactose to glucose

A

galactose + ATP -> Gal-1P + ADP + Pi
Gal-1P (1-P-uridyltransferase) + UDP-glucose -> UDP galactose + Glucose-1P
(1 G1P per galactose)

75
Q

In what circumstances should you absolutely not breastfeed?

A

if infant has metabolic syndrome: PKU or galactosemia

76
Q

Can the HIV virus be passed through milk? Should mothers still breastfeed?

A

Yes, there is chance of infection
(risk if reduced if exclusively breastfed)

Yes, in developing countries, since formula and clean water not readily available

77
Q

What is the cause of breastmilk jaundice, and what are the symptoms? What is the treatment?

A

metabolite in milk (5B-pregnane-3a-20B-diol) will inhibit GLUCORONYL TRANSFERASE, which is needed to conjugate BILIRUBIN for elimination

bilirubin builds up -> yellowing of skin and eyes

treatment: phototherapy, can cease breastfeeding for 24hrs (need to continue pumping)

78
Q

What should be done in the case of eczema in the baby?

A

stopping breastfeeding was found to improve eczema and growth rates

79
Q

The levels of __ and ___ are inadequate in normal breast milk for premature babies, so ___ milk is needed.

A

Ca; P

fortified (breast)

80
Q

What vitamin supplementation is recommended for infants, especially those living in Northern climates?

A

Vitamin D

should not expose babies to sun