Implications of Artificial
Milk Feeding
Dr. Howard Tyler
AnS 337
Lactation Biology
Introduction to Artificial Milks
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Feeding milk or colostrum from one
species to newborns of another widely
practiced
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Precocial vs. altricial species concerns
Cows milk is primary source
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Calves one of most precocial species
Creates composition issues
History of Infant Formula Feeding
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Formula feeding practiced since WWI
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Early formulas had no lactose (considered toxic
until ’30’s)
Knowledge base of infant nutrient
requirements built on errors in formulation of
infant formula
Proteins …
Cow’s Milk-based Formulas
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Two main types:
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1. Protein diluted to reach amount in human
milk
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add back CHO, fat, vitamins and minerals
2. Casein diluted to reach amount in human milk
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add back lactalbumin, fat, vitamins and minerals
Infant Nutritional Requirements
Related to:
 Growth velocity
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Neurological development
Vulnerability to dehydration
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Most rapid rate during lifetime
FAR slower than precocial
species
High surface area:mass
Developmental immaturity
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Digestive tract
Renal function
Developmental Factors Affecting
Infant Nutrition
Digestive tract
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Renal system
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Low lipase levels and bile salt concentration
Low disaccharidase activity except lactase
Low saliva production
Low pancreatic amylase activity
Small stomach volume (10-20 mL)
Low gastric acidity
Low urine concentrating capacity (700 mOsm/L)
Immune system
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Intestinal epithelium permeable to macromolecules
Reconciling Developmental
Barriers to Infant Feeding
Developmental Factor
Addressed by:
 pancreatic lipase activity, Bile salt-stimulated lipases
Medium chain triglycerides
bile salt concentration
 saliva, pancreatic
Simple sugars > Starch
amylases
 gastric acid
Whey > Casein
 intestinal permeability
Solid food introduced when
epithelial closure occurs
Limit protein, Na+, K+, Cl-,
PO4-2 intakes
 urine concentrating
capacity
Osmolality & Renal Solute Load
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Human milk: low, less than 300 mosmolar,
gut can easily handle
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Cow’s milk: higher osmolality
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Creates renal solute load of 13 mosmol/100kcal
Renal solute load of 46 mosmol/100kcal
Skim milk with milk solids added: renal solute
load of 86 mosmol/100kcal
Infant formulas: 18-25 mosmol/100kcal
Potential Problems
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Mixing formulas too strong (or weak)
Skim milk to infants or children under 2 year old
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Whole milk under 1 year old
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Energy:protein ratio
Allergies
Bacterial contamination
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Formula, utensils, water all can be sources
Length of time between mixing and feeding
Proteins
Whey or soluble proteins form very light curds
and are easy to digest
Whey proteins in human milk high in IgA
These antibodies coat the surface of the small intestine, blocking
binding sites to prevent bacterial attachment and allergens
Casein forms very thick curds and is very
difficult to digest
Incidence of colic or pain in abdomen is generally higher in
babies fed on cow’s milk because of thick curds that are formed
from high amount of casein
Fats
Breast milk contains higher levels of
essential fatty acids, linoleic and linolenic
acid, which are essential for the
development of CNS and eyes
Also contains bile salt-stimulated lipase
Fats in breast milk bind less calcium as
compared to other milks
Carbohydrates
Not all the lactose present in breast milk is
absorbed
Some gets fermented producing lactic acid
This helps to make the pH of the lower gut acidic
Acidic pH inhibits the growth of pathogenic bacteria
thus reducing the chances of diarrhea
Acidic pH helps to keep the iron in ferrous form thus
promoting its absorption
Galactose is used during myelinization of the nervous
system
Vitamins
Iron
Calcium
Breast milk contains only about a third of
the calcium as compared to cow’s milk
Absorption of calcium from breast milk is
much better due to low level of phosphates
High levels of lactose also promote
absorption of calcium
Less binding of calcium by fats in the breast
milk also helps in promoting better calcium
absorption
Advantages of Breast Milk Over
Formula
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Antibodies
Less sugar than infant formulas
Contains amino acids, fatty acids, cholesterol not found in
formulas
Growth factors (epidermal growth factor, etc.)
GnRH
Delta sleep inducing peptide
Disadvantages of breast milk:
 harmful substances ingested by mother can pass to
baby (especially lipid-soluble substances)
Anti-infective Properties
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Bifidus factor: stimulates bifidobacteria, which fight
against pathogenic bacteria
IgA, IgM, IgG: immunoglobulins that guard the gut
against infective bacteria
Lactoferrin: binds iron away from bacteria
Macrophages: phagocytosis of infective bacteria
B12 binding protein: removes B12 from bacteria
Protection Against Infection
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Reduces risk and severity of infectious
illness among infants
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diarrhea
otitis media
lower respiratory infections
bacteremia
bacterial meningitis
necrotizing enterocolitis
infant botulism
urinary tract disease
sudden infant death syndrome (SIDS)
colic
Other Health Benefits for Infant
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Enhanced immune response to
immunizations
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Polio
Tetanus
Diptheria
haemophilus influenza
Other Breastfeeding Benefits for Baby
•
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•
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Promotes cognitive development
Better teeth and jaw development
Promotes facial and muscular
development
Promotes normal weight gain
Promotes a strong bond between baby
and mother
Reduces spitting up
Longer-term Health Outcomes
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Reduces risk of chronic illness in childhood
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Some food allergies
Type-1 insulin dependent diabetes
Lymphoma
Asthma
Obesity
Health Benefits for the Mother
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Promotes more rapid return to prepregnancy weight
Reduces risk for certain cancers (lower
estrogen)
 Breast cancer
 Uterine, ovarian, and endometrial cancers
Reduces post-partum hemorrhage
Promotes maternal attachment to baby
Reduces risk of osteoporosis
Saves money (~$1200/year)
Preterm and SGA* Infants:
High Nutritional Risk
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Physiologically immature
Metabolic abnormalities
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Illness present
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Respiratory distress, sepsis, pneumonia, meningitis
Poor nutrient stores
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Fluid and electrolyte imbalances, acidosis
hypo- or hyperglycemia
Fat, glycogen, micronutrients
High nutrient requirements
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Intravenous (parenteral) feeding often necessary
*Small for gestational age
Premature Infants
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Better growth when fed high-protein formula
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Human milk inadequate?
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Pooled mid-lactation breast milk
Milk from mothers of premature infants differs
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High protein, high caloric density
Low iron, riboflavin, vitamin D, folate
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No deficiency symptoms
Breast-fed premature infants have higher IQ at age 8
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About 8 points on average
Composition of Milk
Excerpts from the American Academy of
Pediatrics Policy Statement (Dec. 1997)
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Human milk is uniquely superior for infant feeding
Human milk is the preferred feeding for all infants,
including premature and sick newborns
When direct breastfeeding is not possible, expressed
human milk, fortified when necessary for the premature
infant, should be provided
Exclusive breastfeeding for approximately 6 months
Continuation of breastfeeding for at least 12 months and
thereafter for as long as mutually desired (WHO says 2 yrs.
of age or beyond)
http://www.aap.org/policy/re9729.html
Milk Consumption by
Adult Humans
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Proteins have high biological value, although can be
allergenic
Lactose intolerance primary problem
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Passes into large intestine
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Cramps, bloating, diarrhea
Most commonly develops between ages 1 and 4
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Ethnic differences
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10% white European descent, 70% in blacks
Also high in people of Mediterranean descent
Lactase levels both constitutive and induced
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Some dietary manipulation possible
Neonatal Reflexes in Breast Feeding
Sucking or Suckling?
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Sucking – application of negative
pressure
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Like when you drink through a straw
Suckling involves a co-ordinated use of
the tongue, lips and gums
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Premature infants often lack coordination to
suckle
Suckling
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Nipple, areola, & underlying breast tissue are drawn
into the infant’s mouth
Lips & cheeks form a seal, with the lips flanged outward
Nipple elongates to 2-3 times its resting length into a
teat by suction
Jaw moves the tongue up, compressing the areola
against the alveolar ridge, causing expression from the
milk sinuses
The tongue then moves in a peristaltic motion,
channeling milk to the pharynx for swallowing
Jaw lowers, filling the milk sinuses again
Palate
Teat
Tongue
Problems During Suckling
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Low suction
Inconsistent, irregular suckling bursts
Poor endurance
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Patent ductus arteriosus
Nipple Confusion
Action of sucking from the bottle is very
different from suckling at the breast
In bottle feeding, the baby sucks at the nipple
and uses his tongue to stop the flow of milk
In breast feeding, the baby uses the tongue to
express milk from the breast
Babies who have been bottle-fed try to suck at
the mother’s nipple rather than suckle - often
called nipple confusion
Comparison of Breastfeeding with
Bottle-feeding (Oral Skills)
In bottlefeeding:
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Mouth less open, lips don’t need to be everted
Bottle doesn’t have to be far back in the mouth
Protective tongue action of anterior-superior tongue
movement to stop fluid flow
Difficult to rest at the bottle – milk keeps flowing
Breast feeding
Tongue used to express milk
Bottle feeding
Tongue used to stop milk