Breastfeeding Flashcards
Explain the endocrine control of lactation
Endocrine control of lactation:
- Prolactin and oxytocin are main hormones
-Hypothalamus controls release of both from the pituitary gland
-Prolactin released from anterior pituitary
-Prolactin targets alveolar epithelial cells
-Oxytocin released from posterior pituitary
- Oxytocin targets myoepithelial cells
- LETDOWN REFLEX= Coordinated secretion of prolactin and oxytocin.
PROLACTIN SECRETION: - Baby suckles on nipple> Mechanoreceptors stimulated> Hypothalamus receives nerve signals> Hypothalamus secretes prolactin releasing hormone> Prolactin is released from anterior pituitary to alveolar epithelial cells> milk is released into the alveolar lumen
OXYTOCIN SECRETION: - Hypothalamus sends nerve impulses to posterior pituitary> Posterior pituitary secretes oxytocin to myoepithelial cells> contractions forcibly eject milk from the nipple
- More suckling= more prolactin= more milk
- Lactation stops if suckling doesn’t occur for 7-14 days
Discuss the nutritional requirements of infants and associated maternal dietary changes to meet demands
Discuss the nutritional requirements of infants and associated maternal dietary changes to meet demands:
* Greater requirements for protein, riboflavin, vitamin b12, folate, vitamin c, vitamin a, calcium, magnesium, zinc and copper for the first 4-6 months of lactation
* Most normal diets of women in Westernized countries will be sufficient.
* Comparing UK RNI for lactation and estimated intake for UK women: calcium, magnesium and copper may need increasing
* Study showed Vitamin A and iron deficiencies likely to be observed in infant too however variations in milk were 13%-24% for vitamin A.
* Study showed high PUFA concentrations in babies despite low intake in mothers.
* NHS recommendations: healthy diet, vitamin D supplement, 2 oily fish portions per week max, limit caffeine, limit alcohol (1-2 units per week), stop smoking but don’t stop breastfeeding if they smoke.
* Infant growth: 300% weight gain and 75% height increase from 0-5 years old
* Nutritional requirements of infants:
1-5 years
Energy: 95.8 kcal/kg per day
Protein: 0.94 kcal/kg per day
Folate: 4.0 ug/kg/day
Iron: 0.42 mg/kg/day
Appraise the benefits of breastfeeding to the infant and the mother
Appraise the benefits of breastfeeding to the infant and the mother:
Mother advantages:
- Convenient and cost saving: no need to prepare, can be on demand, no cost to create,
- Uterine recovery: promotes uterus involution
- Delayed return of menstrual cycle
- Preservation of iron stores: due to inhibited production of FSH and LH due to suckling and delayed return of menstrual cycle
- Natural contraception due to delayed return of menstrual cycle (90% effective for 6 months) allows for full recovery following birth , lowers risk of LBW babies
- May result in rapid weight loss of weight gained during pregnancy although studies are difficult to interpret due to lack of control group
- Protection against cancer: ovarian and breast
- Protection against osteoporosis as BMD is recovered once lactation ends completely. There are protective adaptive mechanisms that conserve calcium and promote remineralisation
- Promotes sensitivity to infants needs
Infant advantages:
- Immunoprotection: due to presence of immunoglobulins. Studies show reduced diarrhoea and respiratory infections.
- Immunoglobulins in breast milk: prevent adherence of viruses and bacteria to intestinal mucosa
- Nucleotides in breastmilk: promote immunity
- Non breastfed babies 4x more likely to die. No need to worry about sterilization.
- Cognitive development: longer breast feeding associated with better cognitive ability and less behavioural problems.
- Higher cysteine: methionine ratio supports CNS development
- May protect against sudden infant death
- May be protective against childhood obesity: studies show breast fed babies lower obesity risk in childhood. May be due to baby regulating intake.
- May be protective against allergy formation but evidence is conflicting as early exposure to animal milk is delayed but milk intake from mother may pass on to child
- Benefits to gut microbiome (Carr et al 2021)
- Promotes development of the immature gut
- Lactoferrin and lysozyme: inhibit pathogen multiplication in intestine
- Oligosaccharides : immuno protective: prebiotics: reduces risk of infections and diarrhoea.
Both:
* Emotional bond developed due to close physical contact, eye contact
* Reduced anxiety due to oxytocin through increased parasympathetic activity
Describe the anatomy of human breast
Major site of fat deposition due to oestrogen.
15-20 lobes for milk production and 10-12 lobules.
4 key structures:
* Nipple and areola
* Lactiferous ducts
* Lactiferous sinuses
* Alveolar cells
Nipple and areola
* Smooth muscle cells contract when stimulated causing nipple stiffening.
* Allows baby to take whole area in the mouth
* Nipples have a dark pigment area
* Contains montgomery’s turbercule which provides lubrication
Lactiferous ducts
* Links milk producing tissues to the nipples
Lactiferous sinuses
* At the end of lactiferous ducts (nipple end)
* Limited capacity for milk storage between feeds
* Eject milk when nipple is sucked due to contractile myoepithelial lining
Alveolar cells
* Where milk is created
* Single layer of epithelial cells (take up nutrients from blood and secrete milk) which are polar specialized basal (internal environment) and apical (external environment) cells.
* Apical side contains golgi and fat droplets.
Describe the synthesis of milk within mammary alveolar tissue
- 750-800ml produced per day
- Carbohydrates: lactose 40%
- Fats: triglycerides: 50%
- Protein: casein and whey: 10%
Mostly fat. - Variation between women and between breasts of same woman
- Composition of milk varies throughout day and during the course of lactation
- More fat generally in the evening feeds
- Mother’s fat intake has strong correlation to breast milk contents
- Protein and lactose is relatively stable, not influenced by mother
- Carbohydrate synthesis: mostly lactose 80%, responsible for fluid portion of milk.
Lactose packaged in secretory vesicles, takes up water and electrolytes due to high osmolarity which makes it responsible for fluid portion.
Oligosaccharides make remainder: immuno protective: prebiotics: reduces risk of infections and diarrhoea.
Lactose synthesized in alveolar cells: galactose + glucose via lactose synthetase. Galactose synthesized de novo from glucose, some from maternal diet.
Milk fats: lipid droplets made in alveolar cells, eliminated by exocytosis, some apical layer lost> maternal phospholipids and cell membrane proteins delivered in milk.
Pre term milk: more protein, non protein nitrogen., arachidonic acid and dha.
3 types of milk: Colostrum, transitional milk, Mature milk: fore milk and hindmilk
Describe the synthesis of milk within mammary alveolar tissue
- 750-800ml produced per day
- Carbohydrates: lactose 40%
- Fats: triglycerides: 50%
- Protein: casein and whey: 10%
Mostly fat. - Variation between women and between breasts of same woman
- Composition of milk varies throughout day and during the course of lactation
- More fat generally in the evening feeds
- Carbohydrate synthesis: mostly lactose 80%, responsible for fluid portion of milk.
- Lactose synthesized in alveolar cells: galactose + glucose via lactose synthetase. Galactose synthesized de novo from glucose, some from maternal diet.
Lactose packaged in secretory vesicles, takes up water and electrolytes due to high osmolarity which makes it responsible for fluid portion.
Oligosaccharides make remainder of carbohydrates: immuno protective: prebiotics: reduces risk of infections and diarrhoea.
Milk fats: lipid droplets made in alveolar cells, eliminated by exocytosis, some apical layer lost> maternal phospholipids and cell membrane proteins delivered in milk.
Proteins: casein, alpha-lactalbumin and beta-lactoglobulin synthesized de novo in mammary epithelial cells. , some proteins e.g lactoferrin obtained from maternal circulation. The proteins are delivered in same secretory vesicles as lactose, via exocytosis or as micelles.
Pre term milk: more protein, non protein nitrogen., arachidonic acid and dha.
3 types of milk: Colostrum, transitional milk, Mature milk: fore milk and hindmilk
Discuss trends in breastfeeding in developed and developing countries
- Mothers in the UK breastfeeding for longer
- 1 in 3 still breastfeeding at 6 months in 2010 (1 in 4 in 2005)
- But only 1 in 100 exclusively breastfeeding
- Exclusive breastfeeding higher in less developed countries
- Exclusive breastfeeding is not seen in developed countries
Compare and contrast the nutritional properties of human and formula milk
Compare and contrast the nutritional properties of human and formula milk
Human milk:
* Energy: 69 kcal per 100ml
* Protein: 1.3g per 100ml
* CHO: 7.2g per 100ml
* Lipids: 4.1g per 100ml
Human milk contains more energy: more lipids. Human milk contains less protein. Both have same CHO content. Human milk contains greater amounts of protective proteins.
Human milk: contains caseins, total whey, alpha-lactalbumin, lactoferrin, albumin, lysozyme, immunoglobulins, nucleotides.
* Easier digestibility: Alpha-lactalbumin: essential for lactose synthesis and binding of Ca and Zn ions
* Lactoferrin and lysozyme: inhibit pathogen multiplication in intestine
* Immunoglobulins: prevents adherence of viruses and bacteria to the intestinal mucosa
* composition of human breast milk is dynamic and changes over time,
* during each nursing session (foremilk) is thinner with a higher content of lactose, which satisfies a baby’s thirst
* hindmilk, is creamier with a much higher content of fat for the baby’s needs.
* Variations are also present with the stage of nursing (age of infant), maternal diet, maternal health, and environmental exposure.
* contains two essential fatty acids: linoleic acid and alpha-linolenic acid which are converted to arachidonic acid and docosahexaenoic acid. Important for growth vision, cognitive development.
* higher unsaturated fat content
Formula milk:
* modified cows milk
* cows milk doesn’t contain lysozyme or lactoferrin
Maybe whey dominant: 60:40 whey:casein (similar to breast milk)
or
Casein dominant: 20:80: casein:whey
* alpha lactalbumin might be added
* follow on milk available for >6months: richer in iron, energy, protein, calcium, other micronutrients and essential fatty acids.
* minerals and vitamins are less bioavailable
* nutrients may deteriorate during storage
* Infant formulas have AA and DHA added – the source being fish oils, or fungal and algal oils: not shown to have any health benefit
* nucleotides are added to formula, not sure of bioavailability
* vitamins and minerals are added in higher quantities to increase absorption
* bioavailability of added nutrients unknown
- Energy: 67 kcal per 100ml
- Protein: 1.5g per 100ml
- CHO: 7.2 g per 100ml
- Lipids: 3.6g per 100ml
Identify different formula milk types
- Whey dominant
- Casein dominant
- Follow on milk
- Specialised formulas: pre term, hydolysed, low lactose, lactose free, anti regurgitation, soy based
Preterm – low birth weight babies
Pre term milk: more protein, non protein nitrogen., arachidonic acid and dha.
Partially or extensively hydrolysed and amino acid – for infants with allergies to cow’s milk
Low lactose/lactose free – for infants intolerant to lactose (40% of breast milk and cow’s milk’s CHO is lactose)
Anti-regurgitation – to ↓ GOR
Soy-based – preferably not to be used for infants < 6 months. Concerns about safety due to phytoestrogen content and risk of dental caries (added glucose and maltose). May use for vegan mothers or infants with milk allergy who refuse other types of formulas
What are the 4 key structures of the human breast?
4 key structures of the human breast:
* Nipple and areola
* Lactiferous ducts
* Lactiferous sinuses
* Alveolar cells
Describe the alveolar cells
Alveolar cells
* Where milk is created
* Single layer of epithelial cells (take up nutrients from blood and secrete milk) which are polar specialized basal (internal environment) and apical (external environment) cells.
* Apical side contains golgi and fat droplets.
Describe the lactiferous ducts
Lactiferous ducts
* Links milk producing tissues to the nipples
Describe the nipple and areola
Nipple and areola
* Smooth muscle cells contract when stimulated causing nipple stiffening.
* Allows baby to take whole area in the mouth
* Nipples have a dark pigment area
* Contains montgomery’s turbercule which provides lubrication
Describe the lactiferous sinuses
Lactiferous sinuses
* At the end of lactiferous ducts (nipple end)
* Limited capacity for milk storage between feeds
* Eject milk when nipple is sucked due to contractile myoepithelial lining
Where is milk created?
Milk is created in the alveolar cells
