Does Amount of Protein in Formula Matter for Low-Birthweight Infants? A Cochrane Systematic Review

Organ Growth and Intestinal Functions of Preterm Pigs Fed Low and High Protein Formulas With or Without Supplemental Leucine or Hydroxymethylbutyrate as Growth Promoters

The goal of enteral nutritional support for infants born preterm or small for gestational age (SGA) is to achieve normal growth and development. Yet, this is difficult to achieve because of intestinal immaturity. Our objective was to determine if birth weight, protein intake, and the growth promoters leucine (10 g/L) or calcium-ß-hydroxy-ß-methylbutryate (HMB; 1.1 g/L) would affect trajectories of intestinal growth and functions and weights of other organs. Preterm pigs were delivered at gestational day 105 (91% of term) and fed for 6 or 7 days isocaloric formulas that differed in protein content (50 g or 100 g protein/L), with and without the growth promoters leucine or HMB. For comparative purposes organ weights were measured within 12 h after delivery for six term pigs of low and six of average birth weights. The responses of intestinal growth and total intestinal brush border membrane carbohydrases to protein level and supplemental leucine were of greater magnitude for preterm pigs of lower birth weight. Forskolin stimulated chloride secretion in the proximal small intestine was lower for pigs fed the low protein milk replacers. Capacities of the entire small intestine to transport glucose (mmol/kg-day) were not responsive to protein level, leucine, or HMB, and did not differ between small and large pigs. Relative organ weights of the small and average weight term pigs were similar, but some differed from those of the preterm pigs suggesting preterm birth and the standards of care used for this study altered the trajectories of development for the intestine and other organs. Although leucine is an effective generalized growth promoter that enhances gut development of small preterm pigs, it does not mitigate compromised neurodevelopment. Our findings using preterm pigs as a relevant preclinical model indicate nutrition support strategies can influence development of some gastrointestinal tract characteristics and the growth of other organs.

Growth Responses of Preterm Pigs Fed Formulas with Different Protein Levels and Supplemented with Leucine or β-Hydroxyl β-Methylbutyrate

Growth after preterm birth is an important determinant of long-term outcomes. Yet, many preterm infants suffer ex utero growth retardation. We evaluated effects of leucine and the metabolite, β-hydroxy β-methylbutyrate (HMB) on growth of preterm pigs, a previously-validated translational model for preterm infants. After 48 h of parenteral nutrition preterm pigs were fed for 6 to 7 days isocaloric formulas with different levels of protein (50 or 100 g/L) with leucine (10 g/L, 76 mM) or HMB (at 1.1 g/L, 4 mM) added to stimulate protein synthesis or with alanine (6.8 g/L; 76 mM) as the control. Rates of growth of pigs fed the low protein formula with alanine (3.4 ± 0.2% gain per day) or leucine (3.7 ± 0.2) exceeded that of pigs fed the high protein formula (2.8 ± 0.2, p = 0.02 for comparison with both low protein formulas; p = 0.01 compared with low protein + leucine). Supplementing the high protein formula with leucine or HMB did not increase growth relative to alanine (2.72 ± 0.20, 2.74 ± 0.27, and 2.52 ± 0.20, respectively). Small pigs (<700 g birth weight) grew slower during parenteral nutrition and had a more pronounced response to leucine. Females fed the high protein formulas grew faster than males, and particularly for small pigs (p < 0.05). Blood urea nitrogen values were lower for pigs fed the low versus the high protein formulas (p < 0.05). Leucine and HMB improved growth of preterm pigs fed low, but not high protein formulas, even after controlling for birth weight and sex, which independently correlated with growth rates. They offer an option to improve growth without increasing the amino acid load, with its attendant metabolic disadvantages.

Early nutrition and weight gain in preterm newborns and the risk of retinopathy of prematurity

OBJECTIVE

To identify nutritional and weight gain limitations associated with retinopathy of prematurity (ROP) severity among very preterm newborns.

PATIENTS AND METHODS

1180 infants <28 weeks GA at birth with ROP examination results were grouped and analyzed by quartile of weekly total calorie, carbohydrate, protein, and lipid intake, as well as growth velocity between postnatal days 7 and 28 (adjusted for GA and birth weight Z-score). ROP was categorized by development of no, mild (

RESULTS

Greater risk for Type 1 ROP (risk/95% confidence intervals) was found for infants with lowest quartile receipt of lipids (2.1/1.1, 3.8), total calories (2.2/1.4, 3.6), and carbohydrates (1.7/1.1, 2.9). Development of zone 1 ROP was associated with lipid or total calorie intake in the lowest quartile, and development of stage 3 ROP was associated with lowest quartile of total calorie intake. Growth velocity in the lowest quartile was associated with increased risk of any ROP, including type 1 ROP.

CONCLUSION

The risk of developing severe ROP in extremely premature infants might be reduced by improving nutritional support, specifically targeting lipids and total calories, and perhaps by improving weight gain.

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MESH Headings

• Female
• Humans
• Infant Nutritional Physiological Phenomena/physiology
• Infant, Extremely Premature/physiology
• Infant, Newborn
• Logistic Models
• Male
• Nutritional Status
• Prospective Studies
• Retinopathy of Prematurity/diagnosis
• Retinopathy of Prematurity/physiopathology
• Risk Assessment/methods
• Risk Assessment/statistics & numerical data
• Risk Factors
• Time Factors
• Weight Gain/physiology

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Grants

• 5U01NS040069-05 NINDS NIH HHS
• 2R01NS040069-06A2 NINDS NIH HHS
• R21 EY019253 NEI NIH HHS
• 5P30HD018655-28 NICHD NIH HHS
• 1R21EY019253-01 NEI NIH HHS
• P30 HD018655 NICHD NIH HHS
• U01 NS040069 NINDS NIH HHS

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Affiliation(s)

Deborah K VanderVeen Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Camilia R Martin
Reshma Mehendale
Elizabeth N Allred
Olaf Dammann
Alan Leviton

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A contemporary analysis of parenteral nutrition-associated liver disease in surgical infants

BACKGROUND/PURPOSE

Despite advances in pediatric nutritional support and a renewed focus on management of intestinal failure, there are limited recent data regarding the risk of parenteral nutrition (PN)-associated liver disease in surgical infants. This study investigated the incidence of cholestasis from PN and risk factors for its development in this population.

METHODS

A retrospective review was performed of all neonates in our institution who underwent abdominal surgery and required postoperative PN from 2001 to 2006. Cholestasis was defined as 2 conjugated bilirubin levels greater than 2 mg/dL over 14 days. Nonparametric univariate analyses and multivariate logistic regression were used to model the likelihood of developing cholestasis. Median values with range are presented.

RESULTS

One hundred seventy-six infants met inclusion criteria, and patients received PN for 28 days (range, 2-256 days). The incidence of cholestasis was 24%. Cholestatic infants were born at an earlier gestational age (34 vs 36 weeks; P < .01), required a 3-fold longer PN duration (76 vs 21 days; P < .001), had longer inpatient stays (86 vs 29 days; P < .001), and were more likely to be discharged on PN. The median time to cholestasis was 23 days. Cholestasis was an early development; 77% of cholestatic infants developed cholestasis by 5 weeks of PN exposure. On multivariate regression, only prematurity was significantly associated with development of cholestasis (P < .05).

CONCLUSION

In this analysis, the development of PN-associated liver disease occurred early in the course of exposure to PN. These data help to define the time course and prognosis for PN-associated cholestasis in surgical infants.