Implications of Artificial Milk Feeding Dr. Howard Tyler AnS 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 Nutrition Digestive 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

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: 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 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 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 B 12 binding protein: removes B 12 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, acidosis hypo- 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)

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 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: 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 feedingBottle feeding Tongue used to express milkTongue used to stop milk