Infant nutrition

Infants

Infant Development Swallowing Fetus swallows amniotic fluid at 3-5 months gestation. "Sucking reflex" present at 6 months gestation. Becomes rhythmic at term. Transit time from mouth to stomach -> upped in premature infants but dropped in term infants. Gastric emptying time!!! Gastric half-emptying time shorter in breast fed infants (32 minutes).  72 minutes in formula fed infants. Normal MMC develops in the preterm infant after 10 days of scheduled feeding (rapid adaptation).

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Vit D: Sources of Interaction: 1.Light barriers 2.Bile acid sequestrants 3.Anticonvulasants 4.Isoniazid 5.Mineral oil Inhibit absorption Every breast fed kid gets Vit D for first 6 months Vitamin K "Hemorrhagic disease of the newborn" - seen exclusively in breast fed infants. All infants get preventative intramuscular vitamin K injection at birth. Sources of Interaction: 1.Antibiotics 2.Cholesytramine 3.Coumadin 4.Anticonvulsants Inhibit absorption

Lipid/protein absorption

Lipase activity present in fetal stomach as early as 2nd month of gestation. Lipase activity in pancreas present at 21 weeks gestation. Other sources of lipases: breast milk, tongue. Bile acids Essential for dietary lipid absorption. Increases rapidly in the first 2 months of life. Fetal bile -> mainly taurine conjugated bile acids. Older infants -> Glycine conjugated. Ileal uptake of bile acids is underdeveloped until 8 months of age. Protein Absorption Proteolytic activity seen in the fetus at 16 weeks gestation (gastric pepsin). Normal proteolytic activity is reached by a year of age. Small particles of proteins permeate the intestinal wall during the neonatal period. Pept-1 is H+ coupled and transports more complex proteins (oligopeptides). Various other AA transporters are utilized for certain AAs: 1)IMINO system: Proline, glycine 2)b + system: cationic proteins 3)rBAT system: cystine, dibasic AAs

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Cow's Milk Protein Allergy Tolerance develops over time. 45- 50% at one year. 60 - 75% at 2 years. 85 - 90% at 3 years. Only a small number of patients continue to have problems with CMPA into childhood. Consider re-challenge at 10 - 12 months of age. Eosinophilic enteritis/colitis secondary to CMPA Colonoscopy frequently unnecessary--clinical diagnosis Protein Types in Formula Cow's milk protein (-lactoglobulin) Protein hydrolysate < 1200 kD: 7-8AA in length? Fools the immune system L-amino acid: Don't tolerate protein hydrolysate. Relatively common

Other Absorptions

Account for the nonprotein nitrogen component of breast milk. Essential functions of nucleotides: 1. Cellular immunity Nucleotide deficient-diet in mouse pups leads to abnormal helper T-cell function and decreased macrophage function. 2.up bifidobacteria ("good bacteria") activity. 3. Assist in synthesis of polyunsaturated fatty acids for cell membrane stabilization.

Protein Allergy in infants

Cow's Milk Protein Allergy Allergy to casein (protein) component of cow's milk ( especially -lactoglobulin). Type I allergic rxn.: RAST (IgE), skin prick test No good test exists for Types II, III, IV (cell mediated) CMPA occurs in 0.3% to 7.5% of infants in first 4 months of life. Occurs in 0.5% of breast-fed infants. Can have similar appearance as infant gastroesophageal reflux as well as: Diarrhea Blood in stool Constipation Rash Wheezing Edema Often, family history of atopy (asthma, food allergies, etc.) Mostly a clinical diagnosis. RAST test isn't very good. Blood and mucous in the stool is common. Usually outgrow allergy GERD Dysphagia Hematemesis Melena Rumination Arching Resp. symptoms Aspiration CMPA: Diarrhea Blood in stools Constipation Wheezing Rash Edema Anaphylaxis BOTH: Crying FTT Irritability Emesis Wheezing

Caloric Requirements of the Premature Infant

High Resting metabolic rate in low birth weight infants (premie) 40-50 kcal/kg Protein needs are greater in smaller babies (mirco premie). Linoleic and linolenic acids can't be made--must give them to baby Pre-term protein intake needs to be equivalent to fetal accretion in utero (3.5-4 g/kg/day). Whey protein intake better suited than casein based (compared to AA profiles of breast fed infants). Soy based formulas -> generally not recommended in this age group as protein accretion rates not known. What about breast milk? Keep in mind that breast milk composition changes over time. First 2 weeks of life -> BM mostly fat, protein, Na but low carbohydrates, Ca, and Phos. End of 1st month of lactation -> Protein content of BM cannot keep up with high protein requirements of preterm infants. !!!!Unsupplemented breast milk leads to: 1.Hyponatremia (4-5 weeks) 2.Hypoproteinemia (8-12 weeks) 3.Osteopenia (4-5 months) 4.Zinc deficiency (2-6 months) ***To correct these deficiencies, HUMAN MILK FORTIFIERS are available.

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Human Milk Fortifiers Enfamil Human Milk Fortifier (packets) Simalac Human Milk Fortifier (packets) Simalac Natural Care Fortifier (liquid) HMF adds 1-2 grams protein per 100 mL breast milk. Provides extra protein, essential fatty acids, water-soluble vitamins, fat-soluble vitamins, and trace minerals. DHA / ARA Fat is the major energy source of the preterm infant. Human milk contains docosahexanoic acid (DHA)and arachidonic acid (ARA). ARA is an omega 6 PUFA in phospholipids and an inflammatory mediator DHA is an omega 3 EFA, a major phospholipid in brain, especially the retina Possible benefit of visual acuity in term infants. Preterm effect? Infants rats deficient in PUFA (DHA, ARA) have decreased visual sensitivity. Some studies suggest that visual acuity in breast-fed infants is greater than formula-fed infants.

Infant Energy Absorption

Medium chain TGs don't need active transport: they are easier to absorb. A lot of formulas use this Carbohydrate Absorption Polysaccharide digestion Amylase: Mostly salivary in origin for neonates. Mostly pancreatic in older infants. Breast milk amylase is also available. Glucoamylase: On the brush border -> digests glucose polymers well. Breast milk also has oligosaccharides that alter gut flora ( Bifidobacterium).--(prebiotics provide environment for bacteria to grow) Disaccharide digestion Major enzyme is lactase. "Lactose intolerance" does not occur in infants.!!!!!! Causes of lactase deficiency: congenital (very rare), loss of brush border (infectious, allergic, etc.). Lactase levels decreased in preterm infants compared to term  increased rate of feeding intolerance. Lactase levels decrease again with weaning. Monosaccharide digestion i.e., glucose, galactose, fructose. Actively transported via Na/Glu co-transporter as early as 10 weeks gestation. Glucose: Transport occurs with Na+ and leads to water absorption (i.e., oral rehydration for infectious diarrhea). Fructose: Transported by GLUT5 transporter. Rate-dependent processes: Too much juice! Too much diarrhea! (such as "toddler's diarrhea")

Formulas

Soy Formula Isomil®, Prosobee® Rate of clinical adverse reactions to soy in infants with CMPA is 10 - 67%. Not recommended for CMPA, esp. if non-IgE mediated disease. Most soy allergies are non-IgE mediated. Therefore, not a wise choice of formula in the allergic infant. L-amino acid formula Neocate®, Elecare® Protein is broken down to pure AA (L isomer). Fat content contains MCT (good for pancreatic insufficiency). Very expensive ($100 per case). Use if patient is allergic to protein hydrolysate formula (10%). Insurance companies in texas cover this Protein hydrolysate formula!!!!!!!! Nutramigen®, Pregestimil® (liver disease only), Alimentum® Protein is hydrolyzed into small molecules (<1200 Daltons) with low antigenicity. 90% of infants with CMPA respond well to these formulas. A small % of proteins > 1200 Daltons  small risk of antigenicity.

Other Absorptions

Vitamin Absorption Specific intestinal carriers exist for absorption of water-soluble vitamins. Ex. Na+-dependent multivitamin transporter (SMVT) -> transports biotin and panthothenate. Fat-soluble vitamins (ADEK) -> require use of bile acids for absorption.!! Mineral absorption -> also requires use of specific transporters (Fe, Ca, Zn ,Cu, etc.). Fat Vitamin Absorption Vitamin A Used for growth of epithelial / retinal tissue Liver is primary source of Vitamin A in children. Vitamin A supplementation -> may improve chronic lung disease is premature infants (bronchopulmonary disease). Sources of Interaction: 1.Mineral oil 2.Neomycin 3.Cholestyramine 4.Ethanol Inhibit Vit A absorption Vitamin E Antioxidant that inhibits FA perioxidation in cell membrane.  up polyunsaturated fatty acid -> Vitamin E requirements. Thus, Vitamin E deficiency -> RBC hemolysis

DHA, ARA cont'd

What data is available in humans? May offer cognitive development advantage (esp. in premature infants). Possible significant difference: Bayley scales psychomotor scores, visual evokes potential, forced-choice preferential looking. No significant difference: Behavior rating scale, language subscale. Is there an effect on CNS myelination? Retinal development? Longest study to date... Follow up of children at 4 years of age supplemented with DHA/ARA as infants compared to control group. At 4 years: 1) increased visual acuity, 2) increased IQ maturation (by Wechsler preschool IQ test). All formulas have both now Both available in term / preterm formulas. Provides DHA and ARA in amounts comparable to breast milk. DHA / AHA issues Other factors influence long-term IQ: Education level Socioeconomic status Maternal-infant interaction Long-term studies of IQ are almost impossible to perform.

NEC

Why is the Immune Function Important in Infants, esp. Preterm Infants? Necrotizing enterocolitis. See pneumatosis intestinalis (air in lumen)on imaging Common complication of the premature infant.  Can occur in epidemics in NICU. Due to gut ischemia, prothrombotic state, immunodeficiency, decreased gut mucosal resistance to infection. "Pneumatosis intestinalis" on abdominal film. Treatment: Broad-spectrum abx., NPO, daily abdominal films, surgical resection. Is there a nutritional prevention for N.E.C.? Immature immune system ? Decreased bacterial load susceptible for colonization 1.Feeding delay 2.Broad-spectrum antibiotics Oligosaccharides in breast milk (prebiotic?) Feed ASAP Probiotics Supplementation with normal bacterial flora. Prevents binding of pathogenic bacterial toxins. May enhance IgA production by mucosa. Beneficial bacteria studied  Bifidobacterium, Lactobacillus, Saccharomyces Lin, et al. (Pediatrics, Vol. 115, 2005): Lactobacillus sp. to VLBW infants decreased incidence of NEC. Balance this: Case reports of Lactobacillus sepsis...