Lactation Flashcards
Describe the mechanism of milk production
Neuro-endocrine reflux
Positive feedback system
Birth - Lower progesterone and oestrogen - Prolactin release - a-lactalbumin - Lactose synthase - Lactose
Suckling - Signal to hypothalamus - Pituitary glands release prolactin and oxytocin - Stimulates myoepithelial cells.
Oxytocin - Contracts uterus to original size - Letting down of milk, milk ejection. Moving from milk cells to milk ducts.
Prolactin - Milk production
What are the components of human milk?
Lactose - 72g/l
Protein - 10.5g/l
Fat - 39g/l
Fatty acids composition varies on maternal stores and diet
Components of colostrum
High in protein, immunoglobulin, vitamin A and minerals
Low in lactose and fat
Produced in small amounts
Components of transitional milk
6-10days
High in lactose and fat
Low in protein and minerals
Produced in higher volumes
Components of mature milk
After 2 weeks
750ml/d - depending on demand
Low in vitamin D and iron
Contains growth factor - Polypeptides that stimulate cell growth, only found in human milk
Describe lactose in human milk
40% energy needs
Glucose used by brain
Galactose used in glycolipid synthesis in neural membranes
Facilitates calcium absorption
Osmotically active to ensure adequate H2O content
Describe lactose biosynthesis in mammary cells
UDP galactose + glucose = Lactose + UDP
Synthesised by lactose synthase (a-lactalbumin + galactosyl transferase) - Prolactin
Enhanced by glucose, calcium and glucocorticoids
What milk proteins are found in human milk?
How are they transferred to milk?
40% caseins from micelles
60% whey protein (mostly a-lactalbumin
Non-protein nitrogen - promotes good gut bacteria by producing bifidus factor
- essential amino acids
- protection (immunoglobulins, lactoferrin, lysosomes)
- metal carriers
Amino acids from maternal blood - rough endoplasmic reticulum of milk cell - creates proteins, casein, whey, a-lactalbumin - milk
Describe fat in human milk
How is it transferred into the milk?
Secreted in globules - TAG core and phospholipid membrane
50% milk energy content
FA composition varies on maternal diet and stores
Carrier of fat soluble vitamins
LPL - FFA - FFA: C16
Acetyl CoA - FA synthase - FFA C6-C12
+ Glycerol = TAG globule –> enters milk
What are the functions of the different fatty acids?
N-3 FFA
- Nerve and retina activity
- Foetal brain development
- Eicosanoid synthesis
- Anti inflammatory + anti thrombotic
N-6 FFA
- Eicosanoid synthesis
- Satisfy essential FA requirements
- Pro inflammatory and clotting
N-6 can compete with N-3
Compare HM, formula and CM
Formula well matched to HM
- types of fat in formula vary on brand
CM has more protein
- different casein: whey balance
Unmodified CM has more sodium than HM
Is human milk affected by diet?
Protein, fat and carbohydrate content remains constant
Minerals and calcium also are relatively similar
Draws on maternal reserves to protect the foetus and give adequate supply.
FA composition can vary
H2O soluble vitamins sensitive to diet to a point - if taking supplements it will only absorb them up to a limit
What are the increased requirements for lactation?
Energy + 330kcal/d (6 months exclusive feeding)
Protein + 11g/d (45g –> 56g/d)
Vitamin A + 350 (600ug –> 950ug/d)
Folate + 60ug/d (200ug –> 260ug/d)
Calcium + 550mg/d ( 700mg/d –> 1250mg/d)
What is the calcium increment during lactation?
Calcium + 550mg/d ( 700mg/d –> 1250mg/d)
What is the protein increment during lactation?
Protein + 11g/d (45g –> 56g/d)
