7) Lactation and Breastfeeding (Part I) Flashcards
Why may breastfeeding be referred to as exterior gestation?
As it provides continuity in terms of security and nourishment between the mother and infant
What occurs to progesterone and estrogen secretion following parturition?
They decrease significantly, while other hormones rise to stimulate the secretion of milk
What is the magic hour?
The recommendation that infants be placed in contact with the mother’s breast as soon as possible
Why is a support system crucial for successful long-term breastfeeding?
As psychological inhibitions (e.g. an unsupportive family) may decrease the flow of milk
Which conditions may result in the need of tube-feeding for the baby?
- Low-birth weight infant or neurologically impaired infant
- They are not able to suckle properly on the breast
What stimulates the production of milk? By what cells?
- The suckling stimulus stimulates the release of prolactin from the anterior pituitary
- Stimulates milk production by alveolar cells in mammary glands
What is the function of oxytocin in milk let-down?
- Oxytocin is released from the posterior pituitary
- Stimulates myoepithelial cells of the mammary gland to contract
How does breastfeeding suppress ovulation?
- Decreased levels of estrogen and progesterone
- Increased levels of prolactin
- The rate of breastfeeding must be maintained to prevent ovulation
When should the mother think of using other methods of contraceptives?
When the baby starts to sleep through the night
How does breastfeeding influence the size of the uterus?
- Breastfeeding stimulates the contraction of the uterus
- Results in the involution of the uterus through oxytocin release
What are four advantages of breastfeeding? (4)
1) May aid in proper jaw and tooth development
2) Bacteriologically safe, always fresh, and contains anti-infectious agents
3) Nutritionally superior
4) Associated with a lower risk of food allergies
Provide examples of milk compartments.
- Micelles
- Membrane-bound globules
- Live cells
- Protein
- Non-protein nitrogen compounds
- Carbohydrates
- Lipids
- Vitamins
- Minerals
- Trace elements
What are the three sources of milk components?
1) Transferred from maternal plasma
2) Synthesized from maternal secretory (alveolar) cells from maternal plasma precursors
3) Synthesized from other mammary cells in situ
What are the three phases of milk production? When do they occur?
1) Colostrum (5 to 7 days)
2) Transitional milk (7 days to 3-4 weeks)
3) Mature milk
How does colostrum compare to mature milk? (2)
1) High in protein and mineral content
2) Lower in energy, fat, and lactose content
What quantity of milk does colostrum provide? What does it ressemble?
- The quantity is very small (2-10 mL feeding per day)
- Intense transparent yellow fluid
What explains the intense transparent yellow fluid of colostrum?
Colostrum contains 10 times the carotenoid content of mature milk
How does transitional milk vary from colostrum?
1) Quantity of protein decreases to a consistent level
2) Increase in lactose and fat
How does mature milk vary?
According to the changing infant’s needs (i.e. the time of day, or depending on the age of the child)
What is the composition of foremilk? Why?
- Contains a high quantity of water and lactose
- Due to the increased hydration needs of the child
What is the composition of hindmilk?
Higher in fat and calories
Why are women advised to empty one breast before moving on to the next one?
To provide the infant with a greater quantity of hindmilk, and, thus, a greater quantity of fat to aid in brain development
What are the three immunological properties of breast milk?
1) May have a direct action against pathogens
2) Modulate the immune response
3) Promote the growth and maturation of the GI tract
How do the immunological factors contained in breast milk compare to cow’s milk and infant formula?
- Most immune factors are not found in infant formula
- Lower concentrations are found in cow’s milk
How are whey proteins structurally different than caseins?
They are resistant against proteolysis and acid denaturation
Why are whey proteins resistant against proteolysis and acid denaturation?
Because they contain anti-proteases (e.g. sulfhydryl oxidases)
What is the major function of anti-proteases in whey protein?
- May protect bioactive proteins, enzymes, and immunoglobulins by preserving their disulfide bonds
- Whey proteins contain multiple disulfide bonds, providing a rigid structure that is difficult to digest by proteases
What are the abundant antibodies in breast milk directed against?
- Bacteria
- Bacterial toxins
- Viruses
- Fungi
- Food proteins that may cause allergies
Which antibodies are contained within the mammary gland?
- IgA
- IgM
- IgE
- IgI
Which antibody is contained in the maternal plasma?
IgG
Which antibody forms 90% of secretory antibodies? What does it arise from?
- IgA
- B-cells of the maternal small intestine and respiratory tract
Why is IgA particularly protective against many pathogens?
As the B-cells originate from maternal sites where there is a high exposure to pathogens
____ within the GI tract is resistant to proteolysis, acting on the mucosal surfaces of the GI tract.
IgA
What is the bifidus factor? What is its major function?
- Nitrogen-containing carbohydrate
- Promotes the growth of lactobacilli, decreasing the risk of diarrheal diseases in children
What are lactobacilli?
An important probiotic bacterium that may antagonize the survival of enterobacteria
Studies have demonstrated that breastfed babies have a lower risk of developing diarrhea during childhood, due to what?
Due to the promotion of lactobacilli by the bifidus factor
What is the dominant bacteria in the lower GI of breastfed infants? What is their major function?
- Lactobacilli
- They secrete organic acids and inhibit the growth of pathogen bacteria
What is necrotizing enterocolitis?
- An infection that destroys intestinal tissue
- Causes acute inflammation of the intestinal mucosa
- It is the most common intestinal disease in premature babies
What health issues may cause full-term babies to develop necrotizing enterocolitis? How?
- Bacterial growth that erodes the intestinal wall
- Heart defect: disruption of oxygen or blood flow to the intestine, causing necrosis of the intestinal tissue
What occurs when necrotizing enterocolitis leads to perforation?
Waste products and bacteria within the intestine enter the bloodstream or the abdominal cavity
How is breastfeeding related to necrotizing enterocolitis?
Breastfeeding may reduce the risk of developing necrotizing enterocolitis
Which antimicrobial enzyme is found in human breast milk but not in cow’s milk?
Lysozyme
What is lactoferrin? What is its function in breast milk?
- Lactoferrin is a whey protein
- Produced by milk lymphocytes
- Inhibits siderophilic bacteria (require iron to survive)
Differentiate apo-lactoferrin and holo-lactoferrin.
- Apo-lactoferrin (unconjugated) competes for iron and forms 80% of the lactoferrin in breast milk
- Holo-lactoferrin is conjugated with iron
What is the major function of lactoperoxidases?
Kill Streptococci and enteric bacteria
What is the major function of lipases in breast milk?
- Enhance fat breakdown in the gut
- Their products (FFAs and MAGs) have anti-viral properties
What is the major function of interferons in breast milk? What produces interferons?
- Produced by milk lymphocytes
- Inhibit intracellular viral replication
What is the major function of neutrophils in breast milk?
- Form 90% of white blood cells in milk
- Responsible for phagocytosis and intracellular killing of microbes
What is the major function of macrophages in breast milk?
- Form 10% of white blood cells in milk
- Responsible for the synthesis of complement proteins, lactoferrin, lysozymes, as well as carry-out phagocytosis
What is the major function of complement proteins in breast milk?
- Responsible for the attack of the plasma membranes of pathogens
- Aid in inflammatory processes
- Promote opsonization
What is the major function of fibronectin in breast milk?
Increases phagocytosis
Which hormones stimulate the synthesis of intestinal enzymes and the maturation of the gut mucosa?
- Cortisol
- Thyroxine
- Insulin
What is the major function of prostaglandins as a growth factor in breast milk? Why is it important?
- Stimulate mucus secretion and cell division
- Important as the mucosal barrier of the infant is extremely immature, and it is the first line of defence within the GI tract
What is the major function of polyamines as a growth factor in breast milk? What are examples of polyamines?
- Growth factors that increase cell replication
- Example: spermine and spermidine
What is the major function of insulin-like growth factor as a growth factor in breast milk?
Increases the rate of gut maturation
What is the major function of vitamin E as a growth factor in breast milk?
Stimulates the immune system
The _______ content in milk is directly proportional to the growth rate of the animal.
protein
How does the growth rate of humans compare to other mammals? What may explain this disparity?
- Humans possess an extremely low-growth rate
- The protein content in human breast milk is also low
What are caseins?
- Complexes of caseinates found in micelles, in combination with calcium, magnesium, and phosphates
- Phosphoproteins that occur solely in milk
What minerals do caseins carry? Why?
- Calcium, magnesium, and phosphorus
- The micelle structure allows caseins to carry an ample amount of minerals
What is whey protein?
The thin liquid remaining after the removal of the acid participate of the curd
How does the whey-to-casein ratio in humans compare to cow’s milk?
- 60:40 (whey:casein)
- 40:60 (whey:casein)
How does a greater quantity of whey protein as opposed to casein in breast milk benefit infants?
- Whey forms a soft curd in the stomach
- Increased absorption within the underdeveloped infant GI tract
What are other benefits of whey as opposed to casein?
- Contains a higher proportion of nucleotides
- Better balance of essential amino acids
- Decreased risk of allergic reactions
How does a-lactalbumin concentration compare between cow and human milk?
Human milk has greater a-lactalbumin
How does lactoferrin concentration compare between cow and human milk?
- Human milk has lactoferrin
- Cow’s milk does not
How does B-lactoglobulin concentration compare between cow and human milk?
- Human milk does not have B-lactoglobulin
- Cow’s milk does
How does serum albumin concentration compare between cow and human milk?
Human milk has greater serum albumin
How does IgA concentration compare between cow and human milk?
Human milk has MUCH greater IgA
How does IgG concentration compare between cow and human milk?
Cow’s milk has greater IgG
How does non-protein nitrogen concentration compare between cow and human milk?
Human milk has greater non-protein nitrogen
What is lactalbumin? Where is it synthesized?
- Component of lactose synthetase
- Synthesized in the mammary gland
Which minerals does lactalbumin supply?
Calcium and zinc
Which minerals does xanthine oxidase supply?
Iron and molybdenum
Which mineral does glutathione peroxidase supply?
Selenium
Which minerals does alkaline phosphatase supply?
Zinc and magnesium
Which mineral does lactoferrin supply?
Iron
The iron present in the environment of the GI tract are taken up by ___-lactoferrin to protect bacterial growth.
apo
___-lactoferrin provides iron to the infant.
Holo
What are the two major proteins in human milk?
- Serum albumin
- IgA
What are the two major proteins in cow’s milk?
- B-lactoglobulin
- Serum albumin
Which protein is responsible for most of the antigenicity of cow’s milk? Is it present in human milk?
- B-lactoglobulin
- It is not present in human milk
Bovine serum albumin is different than human serum albumin. What has bovine serum albumin been linked to?
Type I diabetes
Which antibody is closely associated with infant colic? Which type of milk contains this antibody?
- IgG
- Contained largely in cow’s milk
What is infant colic?
- Inconsolable crying and abnominal distress and distension
- The baby cries for at least half an hour consecutively for at least three times a week
What is the major advantage of the high quantity of non-protein nitrogen in human milk?
May be advantageous in terms of digestibility
Breast milk contains a (low/high) quantity of taurine.
high
Which characteristics explain the high quantity of taurine in breast milk?
1) Required for bile acid conjugation
2) Putative neurotransmitter
3) Conditionally essential amino acid in the newborn
Breast milk contains a (low/high) quantity of methionine, and a (low/high) quantity of cysteine.
low
high
Breast milk contains a (low/high) quantity of phenylalanine, and a (low/high) quantity of tyrosine.
low
low
What characteristics explain the low concentration of methionine and high concentration of cysteine in breast milk?
- Allows the utilization of cysteine without the metabolism of methionine
- Important as the metabolism of methionine is impaired in newborns
- Cystathionase is late to develop, which is responsible for the breakdown of homocysteine to cysteine (preventing accumulations of toxic methionine)
What characteristics explain the low concentration of phenylalanine and low tyrosine of cysteine in breast milk?
- Tyrosine aminotransferase and para-hydroxyphenyl pyruvate oxidase are late to develop
- An excess of these amino acids may adversely affect the CNS, as they are neurotoxic
What is the major effect of an excess of blood methionine?
May adversely affect the CNS
When is cow’s milk recommended to infants?
Cow’s milk is NOT recommended to infants
How is IgE linked to the onset of allergies from cow’s milk?
- IgE binds to food proteins to form a complex that binds to receptors on mast cells and basophils
- Causes the release of cytokines, interleukins, and platelet-activating factor to provoke an inflammatory response via histamine release
How is a cow’s milk allergy managed in an infant?
By utilizing formula containing casein or whey protein hydrolysates
If an infant develops a reaction to cow’s milk protein, then they are likely to develop a reaction to ___ milk protein.
soy
Why is soy milk protein not recommended for infant consumption?
- Lower bioavailability of minerals (zinc, calcium, iron), as phytic acid complexes with these minerals, which prevents their absorption
- Decreased calcium and phosphorus retention
- Decreased bone density
Which breast milk protein provides protective effects against milk allergies?
- IgA aids in the blockage of whole food proteins from absorption by binding them
- The reticuloendothelial system clears out the food protein-IgA complex
How does colostrum provide protective effects against milk allergies?
- Infants have leaky junctions within their GI tract, which allows antigens to pass through
- Colostrum hastens the closure of leaky junctions
What is Heiner’s syndrome? How does it primarily present itself?
- Rare hypersensitivity to unheated cow’s milk protein
- Presented primarily as a pulmonary and infectious disease
Is Heiner’s syndrome an allergic reaction or an immunologically-mediated response? What is it associated with?
- Immunologically-mediated response
- GI blood loss, iron deficiency anemia, failure to thrive
What is taurine?
Non-protein nitrogen component
