Journal of Perinatology (2009) 29, 106–111 r 2009 Nature Publishing Group All rights reserved. 0743-8346/09 $32 www.nature.com/jp ORIGINAL ARTICLE Growth in preterm infants fed either a partially hydrolyzed whey or an intact casein/whey preterm infant formula
KN Florendo1, B Bellflower1, A van Zwol2 and RJ Cooke1 1Division of Neonatology, University of Tennessee Center for Health Sciences, Memphis, TN, USA and 2VU Medical Center, Amsterdam, The Netherlands
shorter time to establish full enteral feeds,3 is better in preterm Objective: To compare feeding tolerance, nutrient intake and growth in infants fed partially hydrolyzed whey (pHW) when compared with preterm infants (p32 weeks, p1750 g) fed either a standard preterm infants fed standard intact casein–whey (nonhydrolyzed nonhydrolyzed whey–casein (nHWC) or a partially hydrolyzed whey (pHW) whey–casein, nHWC) protein-based formulas. preterm infant formula. In the past the nutritional adequacy of hydrolyzed whey (HW) Study Design: In this double-blind randomized controlled trial infants proteins in preterm infants has not been uniformly or consistently 4 were fed either formula for at least 3 weeks. Intake was monitored daily, established. Rigo et al. reported reduced protein utilization in serum chemistries and growth weekly. Data were analyzed using analysis preterm infants fed HW when compared with nHWC infant 5 of covariance. formula. Picaud et al. reported that by increasing protein content 10%, equivalent protein and mineral retention and plasma amino- Result: A total of 80 infants were enrolled, 72 completed the study. No acid profiles were obtained with a HW when compared to a nHWC differences were noted in demographic characteristics. No differences were infant formula. detected in feeding tolerance, intakes (118±21 vs 119±14; nHWC vs More recent manufacturing technology may allow for the pHW) or growth weight, 28±1.5 vs 28±1.6 g per day; length, 1.0±0.7 optimization of nutrient availability and amino-acid profile. vs 1.0±0.6 cm per week; head circumference, 0.9±0.4 vs 1.0±0.44 cm Szajewska et al.6 fed preterm infants either an extensively per week). At the end of study, blood urea nitrogen (5.2±3.1 hydrolyzed preterm infant formula, a partially hydrolyzed preterm <6.7±2.3 mg per 100 ml, nHWC
Methods Protein Design 1. Source Non-fat milk, whey Partially hydrolyzed protein concentrate, whey protein, histidine, This prospective, double-blind, randomized, controlled and parallel whey/casein ¼ 60:40 arginine trial was conducted at the Sheldon B. Korones Newborn Center, The 2. Amount (g) 3.0 3.0 Regional Medical Center, University of Tennessee, Memphis. The study was approved by the Institutional Review Board of the Fat University of Tennessee Center for Health Sciences. Written 1. Source MCT, soy, MCT, safflower oil informed consent was obtained from the parents or legally sunflower±safflower oil, (high oleic), palm olein, appointed guardian. DHASCO, ARASCO soybean oil, DHASCO, ARASCO Subjects 2. Amount 5.1 5.2 Premature infants (birth weight p1750 g, estimated gestational age of p34 weeks) were considered eligible. Only those infants of Carbohydrate chronologic age p42 days, tolerating X120 kcal kg 1 per day 1. Source Corn syrup solids, lactose Maltodextrin, lactose (equivalent to >150 cm3 kg 1 per day with 24 kcal per oz 2. Amount (60%, 40%) (55%, 45%) formula) of enteral feeds X24 h and for whom breast milk Vitamin A (IU) 1250 1000 comprised 25% of weekly intake were enrolled. Gestational age p Vitamin D (IU) 240 150 was determined using maternal dates and intrauterine ultrasound. Vitamin E (IU) 6.3 6 Infants with cardiac failure, periventricular or intraventricular Vitamin K (mg) 8 8 hemorrhage grade III or IV, renal disease, sepsis, necrotizing Vitamin C (mg) 20 30 enterocolitis, hepatic dysfunction, lung disease requiring steroids or Calcium (mg) 165 160 continuous diuretic therapy or participation in another trial which Phosphorus (mg) 83 94 might affect nutritional status were excluded. Magnesium (mg) 9 10 Iron (mg) 1.8 1.8 Procedure Zinc (mg) 1.5 1.3 Infants were randomized to one of two formulas by a computer- Copper (mg) 120 150 generated randomization scheme stratified by gender and block- Na (mg) 58 55 randomized by birth weight (<1250 and 1250 to 1750 g) using Chloride (mg) 90 85 one of four different colored labels. Color assignment was kept Nucleotides (mg) 4.2 4.6 hidden until randomization by means of sequentially labeled, Abbreviations: ARASCO, arachidonic acid single cell oil; DHASCO, docosahexaenoic acid sealed opaque envelopes. single cell oil. Ready-to-feed formula was provided in cartons containing 6 89 ml bottles, color-coded by the manufacturer. Infants were times per week to ensure an intake of 150 to 165 ml kg 1 per day. primarily formula-fed but eight infants received fortified human Infants were fed according to a standard unit feeding protocol. milk, 12 to 75 ml per day on a total of 36 subject days. In all cases Infants were initially fed by continuously using an orogastric tube the amount of human milk was less than 25% of weekly caloric until B31 to 32 weeks gestation. At this point, bolus feeds were intake, as determined by study protocol. introduced, initially hourly progressing to three hourly. Once three- The compositions of the study formulas are presented in hourly feeds were established nipple feeds were introduced. Table 1. The compositions differed primarily in the type of protein Feeding tolerance was monitored daily. Feeding intolerance was fed; that is, a nonhydrolyzed protein with a whey/casein ratio of defined as any interruption in enteral feeds once the study formula 60:40 vs a partially hydrolyzed protein that was 100% whey. was fed. If hospital discharge occurred before 21 days of feeding on Otherwise, they were nearly identical in osmolality, vitamin and the study formula, parents were provided with six to eight cartons mineral content. Both contained nucleotides and the long-chain of formula with instructions to feed on demand and return at polyunsaturated fatty acids docosahexaenoic acid and arachidonic predetermined designated times. acid. The study began once the study formula was fed and lasted a Sample size estimation and statistical analysis minimum period of 21 days. During hospital stay, intake volume It was hypothesized that feeding intolerance would be less with the was prescribed by one of the research group and monitored three pHW formula but this is difficult to define in a precise and
Journal of Perinatology Growth in preterm infants KN Florendo et al 108 reproducible fashion in the clinical setting. It was reasoned that to Table 2 Characteristics of study infants (intention-to-treat) be significant intake needed to be curtailed to the extent that Control (n ¼ 38) Treatment (n ¼ 42) growth was affected. Sample size estimation was, therefore, based upon weight gain, a difference of 6 g per day, as well as a standard Birth weight (g) 1166±212 1233±219 deviation (s.d.) of 6 g per day, a statistical power of 0.8 and a 95% Gestational age (w) 29.7±2.2 29.7±2.2 level of significance. The requirement was 72 infants (36 boys, 36 Sex (F:M) 20:18 22:20 girls). Racial Descriptive statistics were used to describe means, s.d. and so on 1. Black 30 36 as well as covariates at baseline. Data were analyzed on an intent- 2. Hispanic 4 2 3. Caucasian 4 4 to-treat and a per protocol basis. Analysis of covariance with 3-week weight, weight gain and so on as the dependent variable, type of Study entry formula as the group membership, sex and birth weight as 1. Postnatal age (day) 19±718±9 stratified variables. The data were also analyzed using corrected age 2. Corrected age (week) 32.2±3.2 32.3±3.2 as a covariant. Results were considered significant at a 95% 3. Weight (g) 1376±200 1419±153 confidence level. 4. Length (g) 40.0±1.8 40.3±1.6 5. Head circumference (cm) 28.7±1.3 28.4±1.1
Abbreviations: F, female; M, male. Results A total of 80 infants, 38 in the control and 42 in the treatment group, were enrolled between 1 July 2004 and 15 December 2005. Table 3 Nutrient intake in study infants (intention-to-treat) Six infants did not complete the study. Two infants were Group Energy Protein randomized but never started because they were too old when the (kcal kg 1 per day)±s.d. (g kg 1 per day)±s.d. study formula could be fed (1, control; 1, treatment), two were discharged home on the study formula but never returned for Week 1 follow-up (1, control; 1, treatment), one infant developed Group B Control 110±21 3.3±0.6 streptococcal sepsis (control group) and one infant developed Treatment 111±14 3.3±0.4 necrotizing enterocolitis (treatment group). In effect, 74 infants completed the study, 72 on a per protocol basis with 38 in the Week 2 Control 123±19 3.7±0.6 treatment and 34 in the control group. Treatment 132±36 4.0±1.1 The characteristics of the two study groups are presented in Table 2. No differences were detected in birth weight, gestational Week 3 age or postnatal age, corrected age or anthropometric Control 143±51 4.3±1.5 measurements at the beginning of the study. No differences were Treatment 137±39 4.1±1.2 detected in sex or racial distributions between the study groups. During the study, four infants had their feedings interrupted (1, Mean intake control group; 3, treatment group). The infant in the control group Control 118±21 3.5±0.6 developed sepsis and was withdrawn from the study. One infant in Treatment 119±14 3.6±0.4 treatment group developed necrotizing entercolitis and was P ¼ NS NS withdrawn from the study. In the two other infants, no pathology Abbreviation: NS, not significant. was detected and feeds were restarted within 24 h. The intake data are presented in Table 3. No differences were detected in crown-heel length or occipitofrontal circumference or detected in nutrient intake, anthropometrics or serum biochemical gain between the groups. determinations between the sexes. Data have therefore been Serum chemistries are presented in Table 5. BUN tended to fall combined. Intakes increased somewhat during the study but no in the control but did not change significantly in the treatment differences were detected in either energy or protein intakes group. At the end of the study; that is, week 3, BUN was lower in between the two study groups over the 3-week study period. the control than treatment group (P<0.001). Total serum proteins Growth in the study groups is presented in Table 4. No and serum albumin fell somewhat during the study but at the end significant differences were noted in weight or weight gain between of study levels were greater in control than the treatment group the groups. Given the observed variance a difference of X3 g per (P<0.05). At the end of the study, no differences were detected in day would have been statistically significant. No differences were serum prealbumin (9.5±1.8 vs 9.2±2.3 mg per 100 ml), retinol-
Journal of Perinatology Growth in preterm infants KN Florendo et al 109
Table 4 Growth in study infants (intention-to-treat) Table 6 Plasma amino acids in study infants (per protocol)
Group Weight (g) Length (cm) OFC (cm) mmol l 1 Control Treatment
Week 1 Total amino acids 3611±86 3590±101 Control 1573±210 41.1±1.7 29.7±1.1 Total indispensable AAa 1628±47 1625±52 Treatment 1615±195 41.4±1.8 29.4±1.2 Total dispensable AAb 1982±52 1965±62
Week 2 Alanineb 419±18 413±34 Control 1758±274 41.9±1.6 30.6±1.1 Asparagineb 73±7.2 69±7.8 (P<0.05) Treatment 1805±186 42.3±1.7 30.2±1.0 Aspartateb 33±3.4 33±4.7 Cysteinea 36±4.3 36±4.2 Week 3 Glutamineb 634±18 634±19 Control 2036±309 43.4±1.8 31.8±1.4 Glutamateb 96±9.3 91±5.2 (P<0.005) Treatment 2017±202 43.4±1.5 31.4±1.1 Glycinea 384±19 383±23 Histidinea 129±9.2 128±12 Gain per day Hydroxyproline 39±4.6 38±6.0 Control 28.1±8.3 1.0±0.3 0.9±0.2 Isoleucinea 78±7.6 76±6.5 Treatment 27.4±4.3 1.0±0.3 1.0±0.2 Leucinea 139±8.8 138±10.1 P ¼ NS NS NS Lysinea 246±14 248±15 Methioninea 37.2±4.2 36.2±3.8 Abbreviation: NS, not significant. Ornithineb 142±11 145±9.9 Phenyalaninea 47.5±3.4 47.4±3.1 Table 5 Serum chemistries in study infants (per protocol) Prolineb 186±13 182±11 Baseline Week 1 Week 2 Week 3 P a TSP (g per 100 ml) Indispensable amino acids. bDispensable amino acids. Control 5.2±0.5 4.8±0.4 4.7±0.4 4.7±0.4 0.05 Treatment 5.2±0.5 4.7±0.3 4.4±0.3 4.4±0.5 The remaining serum chemistries are also presented in Table 5. Albumin (g per 100 ml) Control 2.9±0.3 2.8±0.3 2.7±0.3 2.7±0.3 0.05 Serum calcium did not change in control group and at the end of the study was somewhat greater than in the treatment group Treatment 2.9±0.4 2.6±0.3 2.4±0.2 2.6±0.4 (P<0.001). At the end of the study, serum phosphorus was also greater in the control than treatment group (P<0.001). Serum Calcium (mg per 100 ml) alkaline phosphatase did not change significantly over the course Control 10±0.4 9.9±0.4 9.8±0.3 9.9±0.4 0.001 of the study and no significances were detected between the groups Treatment 9.9±0.5 9.6±0.4 9.5±0.4 9.5±0.5 at the end of the study. No differences were detected in prealbumin, RBP, transferrin or fatty acid profile analyzed at the end of the Phosphorus (mg per 100 ml) study. Control 7.1±0.7 6.7±0.6 6.6±0.6 6.6±0.5 0.001 Plasma amino-acid analyses are presented in Table 6. No ± ± ± ± Treatment 7.1 0.9 6.1 0.5 5.9 0.7 5.9 0.8 significant differences were noted in total amino acid, indispensable; that is, sum of threonine, valine, isoleucine, leucine, Alk.Phos (IU) Control 283±69 294±81 314±91 286±111 NS phenylalanine, lysine, methionine, tryptophan, cysteine, tyrosine Treatment 312 ±126 311±129 324±142 312±122 and histidine, or dispensable; that is, alanine, asparaginine, aspartate, glutamine, glutamate, glycine, hydroxyproline, Abbreviations: BUN, blood urea nitrogen; NS, not significant; TSP, total serum proteins. aAt the end of the study. ornithine, proline and serine, amino acids. The laboratory was unable to provide arginine levels. However, plasma asparigine binding protein (1.7±0.5 vs 1.5±0.4 mg per 100 ml) or (73±7.2 >69±7.8 mmol l 1; P<0.05) and glutamate (96±9.3 transferrin (173±43 vs 166±33 mg per 100 ml) levels between >91±5.2 mmol l 1; P<0.005) were greater in the control than the two groups. treatment group. No differences in any individual amino acid were Journal of Perinatology Growth in preterm infants KN Florendo et al 110 detected between the two formula groups when the Sidak stepdown assimilation (2.7 g kg 1 per day) somewhat exceeded that ‘in procedure was applied to compensate for multiple comparisons. utero’ (2.5 g kg 1 per day) and was paralleled by normal growth (27 g per day) and serum chemistries.8,15 A further examination of the biochemical differences is therefore Discussion warranted. Statistically significant but small differences were noted Even after full enteral feedings have been established, feeds are in BUN, total protein, albumin, calcium and phosphorus levels commonly interrupted in preterm infants.1 In many instances, no between the groups. However, serum levels for both groups were underlying pathology is detected and feeds are soon restarted. Yet, it well within normal limits for preterm infants.16–21 Furthermore, takes time to reestablish full intakes and the accrued nutrient no differences were detected in serum prealbumin, retinol-binding deficit increases.1 We reasoned that if tolerance were better,2,3 protein, transferrin, alkaline phosphatase at the end of the study interruptions would be less frequent, intake would more nor were there differences in weight or length gain between the consistently maintained and, therefore, growth would be greater groups. Collectively, these data suggest that although statistically with the PHW formula. However in this study, tolerance was significant in a large group of infants, the differences are not excellent with both formulas, feeds were interrupted on only four clinically meaningful. Yet, it is important to serially monitor these occasions and no differences were detected in intake or growth biochemical markers as part of routine care in these rapidly between the treatment groups. growing high-risk infants. Yet, despite similar energy and protein intakes BUN was higher, The findings of this study are important. Data from Mihatsch whereas total serum proteins and albumin were lower in infants et al.3 suggest that time to full enteral feeds is shorter when infants fed the pHW formula. This is consistent with the idea that protein are fed a HW infant formula but its’ use is tempered by concerns utilization and metabolism are different with HW when compared for nutritional adequacy.4,22 Data from this study suggest that a to standard nHWC formulas. Rigo and Senterre10 summarized their pHW formula can be fed from the beginning without such extensive experience in this area noting decreased absorption, concerns, a critical consideration in the early establishment of protein utilization (retention/intake) and protein efficiency adequate enteral intakes in these underfed infants. (retention/absorption) in very low birth weight infants fed various Feeding intolerance is common after full enteral feeds have been hydrolyzed protein formulas when compared to nonhydrolyzed established. Data from this study do not support the idea that feeding powdered or liquid formulas. intolerance is less but the overall incidence of intolerance was much Lacroix et al.11 more recently reported transient hyper- followed lower than expected. Tolerance might be better studied under by hypo-aminoacidemia and more rapid transfer of dietary conditions where the incidence of intolerance is higher. Irrespective, nitrogen to serum proteins, serum and urinary urea with whey quicker reestablishment of full enteral intakes may be possible with when compared to micellar casein or total milk protein in adults. the pHW formula after an episode of feeding intolerance.3 These authors concluded that, despite the high Protein Digestibility Hydrolyzed protein formulas are commonly fed postoperatively Corrected Amino Acid Score of the whey proteins, the rate of to preterm infants who have undergone gastrointestinal surgery. amino-acid delivery was too rapid to sustain anabolic requirement However, these formulas were designed to meet the nutritional during the 8-h postprandial period. needs of term infants and many preterm infants are systematically However, important differences exist in protein metabolism underfed. The pHW formula studied in this trial was designed to between preterm infants and adults. Protein turnover rates are meet the unique nutritional needs and supports acceptable growth significantly greater in preterm infants.12–14 The method of of the preterm infant. This is an important step forward in the care feeding is also different; that is, many very low birth weight infants of these undernourished infants. are fed by continuous gastric infusion or every 1 to 2 h and the protein/amino-acid load is likely to be less. At higher turnover rates Acknowledgments and a lower amino-acid load net utilization is likely to be greater. Such may very well have been the case in a more recent nutrient We thank the nursing and medical staff at the Newborn Center, University of balance study.8 Tennessee Center for Health Sciences, Memphis, TN for their support in this study. We In this growth study, infants were fed the same pHW protein as also thank Dr C Hager, Nestec Ltd., Vevey, Switzerland for statistical expertise in analyzing the data. This study was supported by a grant from Nestec Ltd., Vevey, used in the previously conducted balance study at different levels of Switzerland. This study was supported by a grant from Nestec Ltd., Vevey, Switzerland. protein intake, 3.0 and 3.6 g per 100 kcal.8 Irrespective of level of intake, nitrogen utilization (B70%) and efficiency (B85%) were significantly greater than those published by Rigo and Senterre,10 References 62 and 74%, respectively, and similar to those reported by us in 1 Embleton NE, Pang N, Cooke RJ. Postnatal malnutrition and growth retardation: an preterm infants fed standard NHWC preterm formulas, B68 and inevitable consequence of current recommendations in preterm infants? Pediatrics 9 B82%, respectively. At an intake of 3.0 g per 100 kcal, protein 2001; 107(2): 270–273. Journal of Perinatology Growth in preterm infants KN Florendo et al 111 2 Mihatsch WA, Hogel J, Pohlandt F. Hydrolysed protein accelerates the gastrointestinal 12 Beaufrere B. Protein turnover in low-birth-weight (LBW) infants. Acta Paediatr Suppl transport of formula in preterm infants. Acta Paediatr 2001; 90(2): 196–198. 1994; 405: 86–92. 3 Mihatsch WA, Franz AR, Hogel J, Pohlandt F. Hydrolyzed protein accelerates 13 Van Goudoever JB, Sulkers EJ, Halliday D, Degenhart HJ, Carnielli VP, Wattimena JL feeding advancement in very low birth weight infants. Pediatrics 2002; 110(6): et al. Whole-body protein turnover in preterm appropriate for gestational age and small 1199–1203. for gestational age infants: comparison of [15N]glycine and [1-(13)C]leucine 4 Rigo J, Salle B, Picaud JC, Putet G, Senterre J. Nutritional evaluation of protein administered simultaneously. Pediatr Res 1995; 37(4 Part 1): 381–388. hydrolysate formulas. Eur J Clin Nutr 1995; 49: S26–S38. 14 Kalhan SC, Iben S. Protein metabolism in the extremely low-birth weight infant 5 Picaud JC, Rigo J, Normand S, Lapillonne A, Reygrobellet B, Claris O et al. Nutritional [review] [154 refs]. Clin Perinatol 2000; 27(1): 23–56. efficacy of preterm formula with a partially hydrolyzed protein source: a randomized 15 Cooke RJ. Adjustable fortification of human milk fed to preterm infants. J Perinatol pilot study. J Pediatr Gastroenterol Nutr 2001; 32(5): 555–561. 2006; 26: 591–592. 6 Szajewska H, Mrukowicz JZ, Stoinska B, Prochowska A. Extensively and partially 16 Kanakoudi F, Drossou V, Tzimouli V, Diamanti E, Konstantinidis T, Germenis A et al. hydrolysed preterm formulas in the prevention of allergic diseases in preterm infants: Serum concentrations of 10 acute-phase proteins in healthy term and preterm infants a randomized, double-blind trial. Acta Paediatr 2004; 93(9): 1159–1165. from birth to age 6 months. Clin Chem 1995; 41(4): 605–608. 7 Maggio L, Zuppa AA, Sawatzki G, Valsasina R, Schubert W, Tortorolo G. Higher urinary 17 Hammond KB. Interpretation of biochemical values. In: Hathaway WE, Groothuis JR, excretion of essential amino acids in preterm infants fed protein hydrolysates. Acta Hay WW (eds). Current Pediatric Diagnosis and Treatment. Los Angeles CA: Lange Paediatr 2005; 94(1): 75–84. Medical Publishers, 1991 pp 1099–1107. 8 Cooke R, Embleton N, Rigo J, Carrie A, Haschke F, Ziegler E. High protein pre-term 18 Mabry CC, Tietz NW. Reference ranges for laboratory tests. In: Behrman RE, infant formula: effect on nutrient balance, metabolic status and growth. Pediatr Res Kliegman RM (eds). Nelson Textbook of Pediatrics. Philadelphia PA: Saunders, 1992 2006; 59(2): 265–270. pp 1827–1860. 9 Cooke RJ, Watson D, Werkman S, Conner C. Effects of type of dietary protein on 19 Meites S. Clinical Chemistry. 3rd edn. AACC Press: Washington, DC, 1989. acid–base status, protein nutritional status, plasma levels of amino acids, and nutrient 20 Robertson J, Shilkofski N. The Harriett Lane Handbook. 17th edn. St Louis, balance in the very low birth weight infant. J Pediatr 1992; 121(3): 444–451. Elsevier Mosby, 2005. 10 Rigo J, Senterre J. Nutritional needs of premature infants: current issues. J Pediatr 21 Zlotkin SH, Casselman CW. Percentile estimates of reference values for total protein and 2006; 149(5 Suppl): S80–S88. albumin in sera of premature infants (less than 37 weeks of gestation). Clin Chem 11 Lacroix M, Bos C, Leonil J, Airinei G, Luengo C, Dare S et al. Compared with casein or 1987; 33(3): 411–413. total milk protein, digestion of milk soluble proteins is too rapid to sustain the anabolic 22 Zuppa AA, Visintini F, Cota F, Maggio L, Romagnoli C, Tortorolo G. Hydrolysed milk in postprandial amino acid requirement. Am J Clin Nutr 2006; 84(5): 1070–1079. preterm infants: an open problem. Acta Paediatr Suppl 2005; 94(449): 84–86. Journal of Perinatology