Implications of Artificial Milk Feeding

Dr. Howard TylerAnS 337

Lactation Biology

Introduction to Artificial Milks

Feeding milk or colostrum from one species to newborns of another widely practiced Precocial vs. altricial species concerns Cows milk is primary source

Calves one of most precocial species Creates composition issues

History of Infant Formula Feeding

Formula feeding practiced since WWI 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

Two main types: 1. Protein diluted to reach amount in

human milk add back CHO, fat, vitamins and minerals

2. Casein diluted to reach amount in human milk

add back lactalbumin, fat, vitamins and minerals

Infant Nutritional Requirements

Related to: Growth velocity

Most rapid rate during lifetime FAR slower than precocial

species Neurological development Vulnerability to dehydration

High surface area:mass Developmental immaturity

Digestive tract Renal function

Developmental Factors Affecting Infant NutritionDigestive tract

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

Renal system Low urine concentrating capacity (700 mOsm/L)

Immune system Intestinal epithelium permeable to macromolecules

Reconciling Developmental Barriers to Infant Feeding

Developmental Factor Addressed by:

pancreatic lipase activity, bile salt concentration

Bile salt-stimulated lipases Medium chain triglycerides

saliva, pancreatic amylases

Simple sugars > Starch

gastric acid Whey > Casein

intestinal permeability Solid food introduced when epithelial closure occurs

urine concentrating capacity

Limit protein, Na+, K+, Cl-,

PO4-2 intakes

Osmolality & Renal Solute Load Human milk: low, less than 300

mosmolar, gut can easily handle Creates renal solute load of 13

mosmol/100kcal Cow’s milk: higher osmolality

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 Mixing formulas too strong (or weak) Skim milk to infants or children under 2 year

old Energy:protein ratio

Whole milk under 1 year old Allergies

Bacterial contamination 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 acidThis helps to make the pH of the lower gut acidic Acidic pH inhibits the growth of pathogenic

bacteria thus reducing the chances of diarrheaAcidic pH helps to keep the iron in ferrous form

thus promoting its absorptionGalactose 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 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 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

Reduces risk and severity of infectious illness among infants

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

Enhanced immune response to immunizations Polio Tetanus Diptheria haemophilus influenza

• 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

Other Breastfeeding Benefits for Baby

Longer-term Health Outcomes

Reduces risk of chronic illness in childhood Some food allergies Type-1 insulin dependent diabetes Lymphoma Asthma Obesity

Health Benefits for the Mother Promotes more rapid return to pre-

pregnancy 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

Physiologically immature Metabolic abnormalities

Fluid and electrolyte imbalances, acidosishypo- or hyperglycemia

Illness present Respiratory distress, sepsis, pneumonia,

meningitis Poor nutrient stores

Fat, glycogen, micronutrients High nutrient requirements

Intravenous (parenteral) feeding often necessary*Small for gestational age

Premature Infants Better growth when fed high-protein formula

Human milk inadequate? Pooled mid-lactation breast milk

Milk from mothers of premature infants differs High protein, high caloric density Low iron, riboflavin, vitamin D, folate

No deficiency symptoms Breast-fed premature infants have higher IQ at age

8 About 8 points on average

Composition of Milk

Excerpts from the American Academy of Pediatrics Policy Statement (Dec. 1997)

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

Proteins have high biological value, although can be allergenic

Lactose intolerance primary problem Passes into large intestine

Cramps, bloating, diarrhea Most commonly develops between ages 1 and 4

Ethnic differences 10% white European descent, 70% in blacks Also high in people of Mediterranean descent

Lactase levels both constitutive and induced Some dietary manipulation possible

Neonatal Reflexes in Breast Feeding

Sucking or Suckling? Sucking – application of negative

pressure Like when you drink through a straw

Suckling involves a co-ordinated use of the tongue, lips and gums Premature infants often lack

coordination to suckle

Suckling

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

Teat

Tongue

Palate

Problems During Suckling

Low suction Inconsistent, irregular suckling bursts Poor endurance

Patent ductus arteriosus

Nipple Confusion

Action of sucking from the bottle is very different from suckling at the breastIn bottle feeding, the baby sucks at the nipple

and uses his tongue to stop the flow of milkIn breast feeding, the baby uses the tongue to

express milk from the breastBabies 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:

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 Bottle feeding

Tongue used to express milk Tongue used to stop milk