Chapter 5.2 Breast Milk Composition PDF

Chapter 5 – Part II Breast Milk Composition and Recommendations Breast Milk Lipids Milk fat = 2.9 – 5.5% of milk by weight 98% of milk fat = TAGs The rest: DAGs MAGs Cholesterol, cholesterol esters FFA Phospholipids Breast Milk Lipids Within membrane-enclosed milk fat globules Core = TAG Membranes =...

Chapter 5 – Part II Breast Milk Composition and Recommendations Breast Milk Lipids Milk fat = 2.9 – 5.5% of milk by weight 98% of milk fat = TAGs The rest: DAGs MAGs Cholesterol, cholesterol esters FFA Phospholipids Breast Milk Lipids Within membrane-enclosed milk fat globules Core = TAG Membranes = phospholipids, cholesterol & proteins TAGs: main energy source of milk (55 – 60 % of energy) Maternal Milk Lipid Synthesis FAs  16 C: synthesized in alveolar cells from glucose FAs  18 C: maternal adipose stores & diet Maternal Milk Lipid Synthesis ↑ Prolactin ↑ lipoprotein lipase (LPL) activity in mammary gland ↑ FFA uptake into mammary gland Maternal Milk Lipid Synthesis ↓ LPL activity in maternal adipose tissue  FA uptake from diet/internal stores  mammary tissue Maternal Milk Lipid Synthesis Pancereatic lipase acts on TAGs  2-MAGs + FFA  hydrolysis of the 2-position is slow MAGs form better micelles > FFA Palmitic acid = primary SFA in cow’s & human milk fat MAGs with palmitic acid: better absorbed SCFA, PUFA, MUFA: lower melting points  lower [bile salts] to emulsify Maternal Milk Lipid Synthesis Pancereatic lipase acts on TAGs  2-MAGs + FFA MAGs form better micelles > FFA Palmitic acid = primary SFA in cow’s & human milk fat MAGs with palmitic acid: better absorbed SCFA, PUFA, MUFA: lower melting points  lower [bile salts] to emulsify Maternal Milk Lipid Synthesis Long-chain saturated FAs such as stearic acid in the sn1 (or 3) positions  hydrolyzed by pancreatic lipase  bound to calcium or magnesium ions  excreted as an insoluble FA soap Advantages of Human Milk vs. Bovine Milk in Terms of Fat Absorption and Composition Higher proportion of palmitate at 2-position of TAGs Better lipolytic activity (LPL, bile salt stimulated lipases, pancreatic-like lipases) http://advancedlipids.com/the-science-behind-infat/ Positional Distribution of Palmitic Acid in Bovine an Human Milk Triacylglycerols Cow Human Fatty Acid Sn-1 Sn-2 Sn-3 Sn-1 Sn-2 Sn-3 16:0 34.0 32.3 5.4 16.1 58.2 5.5 Advantages of Human Milk vs. Bovine Milk in Terms of Fat Absorption and Composition ↑ Oleic acid & ↓ SFA Oleic acid is better absorbed than saturated fat 5 X greater EFA than cow’s milk Infant formula can be higher (10 – 16% of energy) Linolenic acid: Breast milk 0.7 – 1.3% Formulas 1 – 5% Fatty Acid Composition of Triacylglycerol Fraction of Human and Bovine Milk Fatty Acid Cow Human 14:0 9.5 5.1 16:0 26.3 20.2 18:0 14.6 5.9 18:1 29.8 46.4 18:2 2.4 13.0 Advantages of Human Milk vs. Bovine Milk in Terms of Fat Absorption and Composition EFA precursors insufficient for newborn  developmental immaturity of elongase and desaturase enzymes Breast milk vs. formulas: ~ 5 X LC – PUFA DHA: 0.1 – 0.3% (can be increased by fish intake) Brain [DHA] lower in formula-fed vs. breast fed infants. AA: 0.4 – 0.6% in omnivores (higher than formula) Plasma [AA] lower in formula fed infants BUT brain AA similar Breast Milk Lactose Total [lactose] = 70 g/L – 2nd to water Least variable component 60 – 70% of osmotic pressure of milk No influence of diet on milk [lactose]s Aids in mineral absorption by forming soluble chelates Stimulates beneficial gut bacteria such as lactobacilli Human Milk Oligosaccharides Structurally diverse unconjugated glycans Highly abundant in human milk but generally do not exist in infant formula Minimally digested in the gastrointestinal tract Reach the colon intact, where they act as prebiotics Promote healthy gut colonization Linked with anti-bacterial, anti-viral and antiinflammatory effects Advantages of Human Milk vs. Bovine Milk in Terms of Nutrient Content Better mineral bioavailability Lactalbumin: Ca & Zn Xanthine oxidase: Fe & Mo Glutathione peroxidase: Se Lactoferrin: Fe – highly bioavailable Advantages of Human Milk vs. Bovine Milk in Terms of Nutrient Content Ca:P Breast milk 2:1 Cow’s milk 1.5:1 Lower solute load (Mg, Na, K, Citrate) in human breast milk Major Factors that Influence Breast Milk Composition Gestational age Preterm milk: higher energy, protein, Na & Cl; lower lactose With ↑ length of lactation: ↓ Total protein, Ig’s & fat soluble vitamins ↑ Lactose, fat, energy & water soluble vitamins Fatty Acid Composition of Human Colostrum and Mature Breast Milk Fatty Acid Colostrum Mature Milk 12:0 1.8% 5.8% 14:0 3.8% 8.6% 18:2 n-6 6.8% 7.2% C20 and C22 PUFA 10.2% 2.9% Major Factors that Influence Breast Milk Composition Malnutrition: No effect on immune factors in mature milk ↓Immune factors in colostrum Protein content: affected if prolonged and severe PCM Major Factors that Influence Breast Milk Composition No evidence that alterations in maternal diet affect total milk fat content or milk volume Only severe energy restriction  ↓ milk volume Major Factors that Influence Breast Milk Composition ↑ Maternal body fat content  ↑ milk [fat] Insufficient maternal fat reserves put on during pregnancy  breast milk fat content ↓ to 1.0 g/100 mL The Influence of Diet on Milk Composition Changes in diet: no effect on cholesterol & phospholipid content of milk ↑Milk cholesterol content only in severe hypercholesterolemia Composition of dietary fat will affect FA composition of milk fat The Influence of Diet on Milk Composition Linoleic acid content in breast milk depends on diet Vegetarians have > 30% linoleic acid Omnivores have 6.9 – 18% linoleic acid Very low fat < 1% linoleic acid Linoleic acid < 6% of total fat of infant’s intake  ↑ risk of EFA deficiency Proportions of AA and DHA in RBC Lipids from 14 wk-old Infants Breastfed by Vegans Breastfed by Omnivores Formula fed Sanders, 1999 The Influence of Diet on Milk Composition Fat soluble vitamins not much affected by maternal malnutrition Except vitamin D Excessive maternal vitamin D supplementation can cause toxicity in infant The Influence of Diet on Milk Composition Water soluble vitamins are generally affected by malnutrition Infantile B12 deficiency has been seen in vegetarians Infantile Beri-Beri is seen after being nursed by mother with Beri-Beri The Influence of Diet on Milk Composition Low maternal B6 intake ↑ Risk of B6 deficiency in infant ↓ Attentiveness in infant Low vitamin C intake  ↓ milk content of vitamin C Se & Iodine milk content closely linked to maternal dietary intake Dietary Recommendations During Lactation Maternal nutrition status has minimal impact on macronutrient content of human milk. Fat and protein content of breastmilk can be compromised in extreme conditions. Assess mother’s intake and infant’s growth pattern together to determine nourishment. No specific foods mothers should eat or avoid Dietary Recommendations During Lactation General healthful diet recommended Healthy diet transfers flavors to infant, making them more accepting of low-sugar, low-sodium, vegetable rich diet. Micronutrient considerations among lactating women Diet consisting of whole grains, fruits, and vegetables recommended Should continue prenatal vitamin and vitamin D supplementation while breastfeeding Dietary Recommendations During Lactation Breastmilk of vegetarian/vegan mothers Monitor intake of Protein (essential amino acids), omega-3 essential fatty acids, iron, and calcium, vitamin D and vitamin B 12 Vegetarian diets that contain no animal protein require vitamin B12 and vitamin D supplementation Should check iron levels of breastfed infants of vegetarian or vegan mothers regularly Breastfeeding considerations and contraindications Infants who tire easily, have poor muscle tone or with neurodevelopmental delays May not remove milk effectively May exhaust easily and end feeding session prematurely Breastfeeding management Limit sessions to 30 minutes Increase frequency of feeds to every 2 hours Supplement with 10–30 mL of expressed breastmilk after breastfeeding, if needed Refer to lactation consultant for ongoing aid Breastfeeding considerations and contraindications Infants with special healthcare needs Maternal medical issues Short-term breastfeeding interruption Teach mother skills to help maintain milk supply, including breast pump or hand expression Handle expressed breastmilk in safe, sterile way. Store in glass or polypropylene container. Refrigerator and freezer storage safe Maintain at temperature below 4°C Heat up to 35–37°C for feeding Heat slowly; do not use a microwave Breastfeeding considerations and contraindications Preterm infants Common cause of feeding interruption Neonatal care center may provide pasteurized donor milk if mother’s milk insufficient or unavailable. Teach mother to use hospital-grade pump intended for long-term pumping. Pump at least four times per day and once overnight. Breastfeeding considerations and contraindications Late-preterm infants and small-for-gestational age infants At risk for hypoglycemia, hypothermia, hyperbilirubinemia, dehydration, excessive weight loss, and failure to thrive Require lactation support and frequent evaluation of breastfeeding Benefit from extended skin-to-skin contact during and between nursing sessions Must be fed in early wakefulness during early stages of feeding readiness Breastfeeding considerations and contraindications Low-birth-weight or late preterm infants that fail to meet growth milestones Mothers should be encouraged to pump after feeds to stimulate increase in supply Fortification can be accomplished by Feeding hind milk Adding human milk–based fortifier Can use infant weights to determine exact amount of supplementation needed for infant growth Breastfeeding considerations and contraindications Environmental contaminants Still unclear regarding risk Greater risk for fetuses than for breastfed infants More sensitive CNS Higher dose per kg body weight Less fat tissue to store contaminants Breastfeeding considerations and contraindications Environmental contaminants PCBs & dioxins excreted in higher amounts 1 st week after birth Predominantly from stored levels in maternal adipose tissue Diet: daily intake contributes only 14% of total excretion of dioxins in breastmilk Breastfeeding considerations and contraindications Vitamin K deficiency Breast milk: low in vitamin K Late hemorrhagic disease of the newborn Neonate: Developmental immaturity to synthesize prothrombin Low prothrombin levels (20% of adult values) 1-7 days postpartum Breastfeeding considerations and contraindications Vitamin K deficiency Neonates have poor vitamin K stores at birth Injections of vitamin K (0.5 – 1 mg) given at birth Dioxins & PCBs in breast milk may interfere with vitamin K metabolism PCBs induce cytochromes P450 activity Vitamin K not recycled in the normal salvage pathway but is metabolized and excreted Breastfeeding considerations and contraindications Most commonly used drugs excreted into milk Most medications are compatible Only a handful pose significant health risk Consider dose and duration of use Consult with doctor & pharmacist to identify Drugs less readily excretable in milk Drugs with short half-life Breastfeeding considerations and contraindications Social drugs completely contraindicated for breastfeeding (hallucinogenic drugs) Risk of infant dependence on opioids, heroin, morphine, etc. Alcohol depresses infant’s intake of milk and milk production is decreased by alcohol Breastfeeding considerations and contraindications If mother is taking anticonvulsants  infant may need vitamin K supplements Mother taking oral contraceptives: Can cause gynecomastia in young infants Suppress lactation Breastfeeding considerations and contraindications Antibiotics: allergic reactions, sleepiness, vomiting & refusal to eat Caffeine of 1-2 cups/d: restlessness, irritability & sleeplessness in the infant Sedatives cause lethargy in infants Smoking decreases milk volume Hot spices and garlic may cause distress in infant Breastfeeding considerations and contraindications Phenylketonuria (PKU) Requires special formula; breastfeeding must be stopped Lofenalac - infant formula with low PHE content Galactosemia – rare autosomal recessive disorder Deficient 1-P-uridyl transferase  cannot convert galactose to UDP-galactose Galactose-1-P accumulates  Galactitol, highly toxic Severe mental retardation, cataracts and liver damage Requires special formula; breastfeeding must be stopped Breastfeeding considerations and contraindications Human immunodeficiency virus (HIV) Can be transferred through breastfeeding Mother should be provided with appropriate therapy to decrease viral loads Infants should be regularly tested throughout first year of life Not automatically contraindicated if mother has low, controlled viral load and takes medication as instructed Breastfeeding considerations and contraindications Neonatal jaundice 5β-pregnane-3α,20β-diol inhibits bilirubin conjugation by glucoronyl transferase Presents as yellowing of skin and whites of eyes Risk factors: Maternal health issues Prematurity or low birth weight Neonatal bruising Excessive weight loss as an early neonate Can be breastfed Baby may be lethargic during light treatment and require prompted feedings every 2 hours. Breastfeeding considerations and contraindications Infants who had developed eczema while exclusively breastfed Onset was associated with blunting of growth After breastfeeding was discontinued, symptoms of atopic eczema and rates of growth improved Prolonged breastfeeding without introduction of solids beyond 6 months  ↓ growth rate, feeding aversion Breastfeeding considerations and contraindications Fe deficiency may occur after 4 – 6 months if Fe-rich foods not introduced Not important for formula fed infants Breastfed infants to receive Fe supplements? Controversial Healthy breastfed infants receiving iron drops from 1- 6 months of age Improved psychomotor development and visual acuity American Academy of Pediatrics recommends all exclusively breastfed infants should receive iron drops of 1 mg/kg/day at 4 months of age Breastfeeding considerations and contraindications Breastfed infants can synthesize additional vitamin D through routine sunlight exposure (not recommended). But vitamin D supplements (10 μg/d) should be provided to exclusively breastfed infants (poor exposure to sunlight in Northern climates) Mother can supplement with high doses (100 μg/d) to increase amount of vitamin D in milk Efficacy depends on the mother's vitamin D status and daily infant milk intake Support and Education for Breastfeeding Current recommendations Infants be exclusively breastfed until 6 months of age Then as a supplement to developmentally appropriate solid foods up to age 24 months Increase overall breastfeeding rates by Peer support for breast feeding Adequate professional education before and during breastfeeding Society-level support in the form of laws, worksite programs, and protections for breastfeeding