Nutrition During Lactation PDF

Chapter 6 Nutrition during Lactation “One of the best things that only you can do is breastfeed your baby for as long as possible. The longer a mom and baby breastfeed, the greater the benefits are for both mom and baby.” The National Women’s Health Information Center, 20...

Chapter 6 Nutrition during Lactation “One of the best things that only you can do is breastfeed your baby for as long as possible. The longer a mom and baby breastfeed, the greater the benefits are for both mom and baby.” The National Women’s Health Information Center, 2002  Lactation Physiology Key Terms Mammary gland – source of milk for offspring, AKA breast Alveoli – rounded or oblong shaped cavity present in breast Secretory cells – cells in acinus (milk gland) that are responsible for secreting milk components into ducts  Lactation Physiology More Key Terms Myoepithelial cells – line the alveoli & can contract to cause milk to be secreted into ducts Oxytocin – hormone produced during letdown that causes milk to eject into ducts Lactiferous sinuses – larger ducts for storage of milk behind the nipple  Lactation Physiology And More Key Terms Lobes –rounded structures of mammary glands Lactogenesis –term for human milk production Breast of a Lactating Female  Functional Units of the Mammary Glands Avleoli in mammary glands are the functional units Each is composed of secretory cells with a duct in the center Myoepithelial cells, that line the alveoli, contract during letdown causing milk ejection Milk is stored in lactiferous sinuses Mammary Gland Development During puberty, the ovaries mature with increases in estrogen & progesterone Hormones impacting lactation and their functions are in the table below  Mammary Gland Development Estrogen & progesterone increase during puberty Levels of both hormones increase dramatically to prepare mammary glands for lactation Note the increase in size & development Breast Development from Puberty to Lactation  Stages of Lactogenesis Lactogenesis I (birth to 2-5 days) milk formation begins Lactogenesis II—(begins 2-5 days after birth) increased blood flow to breast; milk “comes in” Lactogenesis III—(begins at ~10 day after birth) milk composition is stable  Hormonal Control of Lactation Prolactin – Stimulates milk production – Released in response to suckling, stress, sleep, & sexual intercourse Oxytocin – Stimulates letdown – Tingling of the breast may occur corresponding to contractions in milk duct – Causes uterus to contract, seal blood vessels, & shrink in size  The Letdown Reflex An infant suckling at the nipple usually causes letdown  Human Milk Composition Human milk is the only food needed by the majority of healthy infants for ~ 6 months – It nurtures & protects infants from infectious diseases The composition changes over a single feeding, over a day, based on age of the infant, presence of infection in the breast, with menses, & maternal nutrition status Colostrum The first milk secreted during the first few days postpartum Very high in proteins such as secretory IgA & lactoferrin  Water and Energy in Human Milk Water – Major component in human milk – Isotonic with maternal plasma Energy – ~0.65 kcal/mL – Higher-fat milk has more calories than lower- fat milk – Lower in calories than human milk substitute (HMS)  Lipids in Human Milk Lipids—provide ½ the calories in human milk Effect of maternal diet on fat composition – Fatty acid profile reflects dietary intake of mother – Very  fat diet with adequate CHO & protein, milk is  in medium-chain fatty acids  DHA, Trans Fatty Acids, and Cholesterol in Human Milk DHA (docosahexaenoic acid) Essential for retinal development – Associated with higher IQ scores Trans fatty acids – Present in human milk from maternal diet Cholesterol – Higher in human milk than HMS – Early consumption of cholesterol through breast milk appears to be related to lower blood cholesterol levels later in life  Proteins in Human Milk Total proteins –Lower than in whole cow’s milk (0.32 vs. 0.98 g/oz) –Have antiviral & antimicrobial effects Casein –Main protein in mature human milk –Facilitates calcium absorption  Proteins in Human Milk Whey – A soluble protein that precipitates by acid or enzyme – Some minerals, hormones & vitamin binding proteins are part of whey Non-protein nitrogen – ~20-25% nitrogen in human milk – Used to make non-essential amino acids  Milk Carbohydrates Lactose –Dominant CHO –Enhances calcium absorption Oligosaccharides –A medium-length CHO –Second dominant CHO –Prevent binding of pathogenic microorganisms to gut, which prevents infection & diarrhea  Fat-Soluble Vitamins in Human Milk Vitamin A –Content in colostrum is ~double that of mature milk –Yellow color from beta-carotene Vitamin D –Most as 25-OH2 vitamin D –Content reflective of mother’s exposure to sun  Fat-Soluble Vitamins Vitamin E – Level linked to milk’s fat content – Level not adequate to meet needs of preterm infants Vitamin K – ~5% of breastfed infants at risk for K deficiency based on clotting factors – Infants who did not receive K injection at birth may be deficient  Water-Soluble Vitamins in Human Milk Water soluble in general – Content reflective of mother’s diet – Vitamin most likely to be deficient is B6 Vitamin B12 and folate – Bound to whey proteins – Low B12 seen in women who: have hypothyroidism or latent pernicious anemia are vegans or malnourished have had gastric bypass  Minerals in Human Milk Minerals contribute to osmolality – Content related to growth of infant – Concentration decreases over 1st 4 months, except for magnesium Bioavailability – Most have high bioavailability – Exclusively breastfed infants have very low risk of anemia despite low iron content of human milk  Trace Minerals in Human Milk Zinc – Bound to protein & highly available – Rare defect in mammary gland uptake of zinc may cause zinc deficiency that appears as diaper rash Other trace minerals – Fluoride is only mineral not affected by mother’s diet  Taste of Human Milk Flavor of foods in mother’s diet influences taste of breast milk – Infants seem more interested in mother’s milk if flavor is new Exposure to a variety of flavors may contribute to infant’s interest & acceptance of new flavors in solid foods  Benefits of Breastfeeding for Women Hormonal benefits – Increased oxytocin stimulates uterus to return to prepregnancy status Physical benefits – Delay in monthly ovulation resulting in longer intervals between pregnancies Psychosocial benefits – Increased self-confidence & bonding with infant  Benefits of Breastfeeding for Infants Nutritional benefits Immunological benefits – Lower infant mortality in developing countries – Fewer acute illnesses Reductions in chronic illnesses Breastfeeding & childhood overweight Cognitive benefits Socioeconomic benefits Analgesic effects  Breast Milk Supply and Demand Can women make enough milk? Does the size of the breast limit a woman’s ability to nurse? Is feeding frequency related to the amount of milk a woman makes? Pumping or expressing milk Can women breastfeed after breast reduction/augmentation? Does silicone from breast implants leach into the milk?  The Breastfeeding Infant Optimal duration of breastfeeding – AAP 1 year or longer – U.S. Surgeon General exclusively for 6 months & best to breastfeed for 12 months Reflexes – Gag reflex—prevents infant from taking things into lungs – Oral search reflex—infant opens mouth wide when close to breast & thrusts tongue forward – Rooting reflex—infant turns to side when stimulated on that side  The Breastfeeding Infant Identifying hunger and satiety – Hunger is signaled by infant bringing hands to mouth, sucking on them, & moving head from side to side – Crying is late sign of hunger – Allow infant to nurse on one breast as long as they want to ensure they get hindmilk with its high fat content that provides satiety Note: High lactose content of foremilk may cause diarrhea  The Breastfeeding Infant Feeding frequency – 10-12 feedings/day are normal for newborns – Stomach emptying occurs in ~1½ hours Vitamin supplements for breastfeeding infants – Vitamin K—all U.S. infants receive injections at birth – Vitamin D—exclusively breastfed infants need supplements at 2 months  Identifying Breastfeeding Malnutrition Normal weight loss for newborns ~7% of birthweight in 1st week Weight loss of 10% needs evaluation by lactation consultant Malnourished infants become sleepy, non-responsive, have a weak cry, & wet few diapers – By day 5 to 7, infants should have 6 wet diapers & 3-4 soiled diapers  Energy and Nutrient Needs for Lactation Energy needs vary by activity level DRI is 500 kcal/day for the 1st 6 months & 400 kcal/d afterward Components of maternal diet may be linked to colic. – Culprit foods: cow’s milk, eggs, peanuts, tree nuts, wheat, soy, & fish  Maternal Energy Balance and Milk Composition Protein-calorie malnutrition – results in reduction in milk volume but not quality Weight loss during breastfeeding – Theoretically, the caloric DRI assume a loss of 0.8 kg/month – Most women do not reach prepregnancy weight by 1 year after birth – Modest or short-term energy reductions do not decrease milk production  Exercising and Breastfeeding Modest energy restriction combined with increased activity may help women lose weight & body fat Exercise does not inhibit milk production or infant growth Aerobic activity enhances fatty acid mobilization Restriction in energy intake enhances prolactin