Breast milk composition Flashcards
In what form are lipids found in milk, in terms of structure? What is the location of different lipids?
in membrane bound micelles (globules)
membrane: PL, C (also proteins)
core: TG
Carbs can be converted to what types of fatty acids? What cells do this, to add to breast milk?
non essential FA (16C or less)
alveolar cells
total fat in milk is about ___%
3-5.5%
What type of diet is a baby on? Why is this necessary (3)?
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
What types of lipids are in milk? What is the main type?
98% is triglycerides also: FFA MAG DAG cholesterol + CE PL
What is the importance of TGs in milk?
dense energy source
What are the products of lipolysis?
1 MAG
2 FFA
What hormone stimulates milk lipid production? What are its effects (2)?
prolactin
increase in mammary gland LPL (lipoprotein lipase) activity (increase uptake of FFA into mammary gland)
decrease in adipose LPL activity
Which position on a TG is resistant to lipolysis?
position 2 (middle)
how does human milk differ from bovine in terms of TG composition?
more PALMITATE on position 2 of TGs
Describe the role of LPL on milk production:
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
Where do milk lipids come from? (2)
16C or less: synth from carbohydrates by alveolar cells
18C or more: from maternal stores or diet
The primary saturated fat in milk is _____
palmitic acid
What are the advantages of having more palmitate in position 2? (4)
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
What enzymes facilitate the digestion of lipids in the infant (4)?
What enzyme is only produced in tiny amounts, and why?
gastric lipase
Bile-salt stimulated lipase (from milk)
LPL
pancreatic-like lipases
Pancreatic lipase; pancreas not yet mature enough to function fully
compared to cow milk, human milk has (more/less) saturated fat, and more ____ acid. What are the implications of this?
less saturated fat
more oleic acid
oleic acid is more easily absorbed
List in order of increasing EFA content:
fortified formula, cow milk, breast milk
cow < breast < fortified formula
Even though formula can have more EFAs, why might breast milk still be better in meeting the infants essential lipids requirements?
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)
What lipids require fewer bile salts to emulsify? why?
short chain FA (less hydrophobic)
MUFA (lower melt point)
PUFA (lower melt point)
Why is DHA important?
How can the mother increase DHA content in milk?
retinal PL, membranes for brain!
(proper vision + brain dev)
more fatty fish in diet
true/False: formula fed infants will have lower arachidonic acid concentration in brains
false; brain not affected
but plasma conc is lower!
What enzyme types are needed for converting EFAs into other PUFAs?
elongases and desaturases
What is the main component of milk (after water) and the least variable (constant %)?
lactose
the osmolality of milk is identical to ____. Why is this important?
plasma
lowers energy cost of making milk; otherwise would need to expend energy to maintain osmotic gradient
What are some advantages of human vs cow milk in terms of minerals? (3)
- better absorbed due to proteins and enzymes in milk
- higher Ca:P ratio
- lower solute load (less Na, K, Mg, citrate) -> less kidney strain
what are the roles of lactose in milk? (4)
- provide carbohydrate in diet
- maintain milk osmolality
- aids in absorption of minerals (chelates and solubilizes)
- help lactobacilli (gut bacteria)
what proteins in breast milk aid Fe absorption?
Lactoferrin, xanthine oxidase
Glutathione PO aids in absorption of:
Se
What proteins in breast milk aid in Zn absorption?
Lactalbumin, alkaline phosphatase
Lactalbumin aids in absorption of ___ and ___.
Ca, Zn
What protein in breast milk aids in absorption of Mo?
xanthine oxidase
_____ in breast milk aids in absorption of Zn and ___.
alkaline phosphatase
Mg