Protein hydrolysate formula maintains homeostasis of plasma amino acids in preterm infants

Shorter Time to Full Preterm Feeding Using Intact Protein Formula: A Randomized Controlled Trial

Background: This study was carried out to evaluate enteral feeding advancement and tolerance in preterm infants receiving one of two marketed formulas: intact protein preterm formula (IPF) or extensively hydrolyzed formula (EHF) for the first 14 feeding days. Methods: Primary outcome was days to full enteral feeding (≥140 mL/kg/day). Per protocol analyses included the following: all participants who met study entrance criteria and completed study feeding (primary) and those who received ≥75% enteral intake from study formula (subset). Mothers were encouraged to provide their breast milk. Results: Of the 65 enrolled (IPF: n = 32; EHF: n = 33), 60 completed study feeding per protocol (IPF: n = 30; EHF: n = 30), 37 (62%) received predominantly breast milk, and 23 (38%) received ≥75% study formula intake (IPF: n = 11; EHF: n = 12). No group differences were detected in tolerance measures. No necrotizing enterocolitis (NEC) was reported. Median time to achievement of full enteral feeding was significantly shorter for the IPF vs. EHF group (day 10 vs. 14, p < 0.05) (subset analysis). Mean enteral intake significantly increased by day 14 for the IPF group (p < 0.05), reflecting group divergence as achieved feeding volumes increased. Conclusions: Results suggest shorter time to full enteral feeding and higher feeding volume achieved by study end in preterm infants receiving intact protein preterm formula versus extensively hydrolyzed formula.

Protein hydrolysate versus standard formula for preterm infants

BACKGROUND

When human milk is not available for feeding preterm infants, protein hydrolysate, rather than standard cow's milk formulas (with intact proteins), is often used because it is perceived as being tolerated better and less likely to lead to complications. However, protein hydrolysate formulas are more expensive than standard formulas, and concern exists that their use in practice is not supported by high-quality evidence.

OBJECTIVES

To assess the effects of feeding preterm infants hydrolysed formula (vs standard cow's milk formula) on risk of feed intolerance, necrotising enterocolitis, and other morbidity and mortality.

SEARCH METHODS

We used the standard Cochrane Neonatal search strategy including electronic searches of the Cochrane Central Register of Controlled Trials (CENTRAL; 2019, Issue 1), in the Cochrane Library; Ovid MEDLINE (1966 to 28 January 2019); Ovid Embase (1980 to 28 January 2019); and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (28 January 2019), as well as conference proceedings and previous reviews.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials that compared feeding preterm infants protein hydrolysate versus standard (non-hydrolysed) cow's milk formula.

DATA COLLECTION AND ANALYSIS

Two review authors assessed trial eligibility and risk of bias and extracted data independently. We analysed treatment effects as described in the individual trials and reported risk ratios and risk differences for dichotomous data, and mean differences for continuous data, with respective 95% confidence intervals (CIs). We used a fixed-effect model in meta-analyses and explored potential causes of heterogeneity in sensitivity analyses. We assessed quality of evidence at the outcome level using the GRADE approach.

MAIN RESULTS

We identified 11 trials for inclusion in the review. All trials were small (total participants 665) and had various methodological limitations including uncertainty about methods to ensure allocation concealment and blinding. Most participants were clinically stable preterm infants of less than about 34 weeks' gestational age or with birth weight less than about 1750 g. Fewer participants were extremely preterm, extremely low birth weight, or growth restricted. Most trials found no effects on feed intolerance, assessed variously as mean pre-feed gastric residual volume, incidence of abdominal distension or other gastrointestinal signs of concern, or time taken to achieve full enteral feeds (meta-analysis was limited because studies used different measures). Meta-analysis showed no effect on the risk of necrotising enterocolitis (typical risk ratio 1.10, 95% CI 0.36 to 3.34; risk difference 0.00, 95% CI -0.03 to 0.04; 5 trials, 385 infants) (low-certainty evidence; downgraded for imprecision and design weaknesses).

AUTHORS' CONCLUSIONS

The identified trials provide only low-certainty evidence about the effects of feeding preterm infants protein hydrolysate versus standard formula. Existing data do not support conclusions that feeding protein hydrolysate affects the risk of feed intolerance or necrotising enterocolitis. Additional large, pragmatic trials are needed to provide more reliable and precise estimates of effectiveness and cost-effectiveness.

Infant formulas containing hydrolysed protein for prevention of allergic disease

BACKGROUND

Infant formulas containing hydrolysed proteins have been widely advocated for preventing allergic disease in infants, in place of standard cow's milk formula (CMF). However, it is unclear whether the clinical trial evidence supports this.

OBJECTIVES

To compare effects on allergic disease when infants are fed a hydrolysed formula versus CMF or human breast milk. If hydrolysed formulas are effective, to determine what type of hydrolysed formula is most effective, including extensively or partially hydrolysed formula (EHF/PHF). To determine whether infants at low or high risk of allergic disease, and whether infants receiving early short-term (first few days after birth) or prolonged formula feeding benefit from hydrolysed formulas.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2017, Issue 11), MEDLINE (1948 to 3 November 2017), and Embase (1974 to 3 November 2017). We also searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles and previous reviews for randomised controlled trials and quasi-randomised trials.

SELECTION CRITERIA

We searched for randomised and quasi-randomised trials that compared use of a hydrolysed formula versus human milk or CMF. Outcomes with ≥ 80% follow-up of participants from eligible trials were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, assessed trial quality and extracted data from the included studies. Fixed-effect analyses were performed. The treatment effects were expressed as risk ratio (RR) and risk difference (RD) with 95% confidence intervals and quality of evidence using the GRADE quality of evidence approach. The primary outcome was all allergic disease (including asthma, atopic dermatitis, allergic rhinitis and food allergy).

MAIN RESULTS

A total of 16 studies were included.Two studies assessed the effect of three to four days infant supplementation with an EHF while in hospital after birth versus pasteurised human milk feed. A single study enrolling 90 infants reported no difference in all allergic disease (RR 1.43, 95% CI 0.38 to 5.37) or any specific allergic disease up to childhood including cow's milk allergy (CMA) (RR 7.11, 95% CI 0.35 to 143.84). A single study reported no difference in infant CMA (RR 0.87, 95% CI 0.52 to 1.46; participants = 3559). Quality of evidence was assessed as very low for all outcomes.No eligible trials compared prolonged hydrolysed formula versus human milk feeding.Two studies assessed the effect of three to four days infant supplementation with an EHF versus a CMF. A single study enrolling 90 infants reported no difference in all allergic disease (RR 1.37, 95% CI 0.33 to 5.71; participants = 77) or any specific allergic disease including CMA up to childhood. A single study reported a reduction in infant CMA of borderline significance (RR 0.62, 95% CI 0.38 to 1.00; participants = 3473). Quality of evidence was assessed as very low for all outcomes.Twelve studies assessed the effect of prolonged infant feeding with a hydrolysed formula compared with a CMF. The data showed no difference in all allergic disease in infants (typical RR 0.88, 95% CI 0.76 to 1.01; participants = 2852; studies = 8) and children (typical RR 0.85, 95% CI 0.69 to 1.05; participants = 950; studies = 2), and no difference in any specific allergic disease including infant asthma (typical RR 0.57, 95% CI 0.31 to 1.04; participants = 318; studies = 4), eczema (typical RR 0.93, 95% CI 0.79 to 1.09; participants = 2896; studies = 9), rhinitis (typical RR 0.52, 95% CI 0.14 to 1.85; participants = 256; studies = 3), food allergy (typical RR 1.42, 95% CI 0.87 to 2.33; participants = 479; studies = 2), and CMA (RR 2.31, 95% CI 0.24 to 21.97; participants = 338; studies = 1). Quality of evidence was assessed as very low for all outcomes.

AUTHORS' CONCLUSIONS

We found no evidence to support short-term or prolonged feeding with a hydrolysed formula compared with exclusive breast feeding for prevention of allergic disease. Very low-quality evidence indicates that short-term use of an EHF compared with a CMF may prevent infant CMA. Further trials are recommended before implementation of this practice.We found no evidence to support prolonged feeding with a hydrolysed formula compared with a CMF for prevention of allergic disease in infants unable to be exclusively breast fed.

Protein hydrolysate versus standard formula for preterm infants

BACKGROUND

When human milk is not available for feeding preterm infants, protein hydrolysate rather than standard cow's milk formulas (with intact proteins) are often used because they are perceived as being tolerated better and less likely to lead to complications. However, protein hydrolysate formulas are more expensive than standard formulas, and concern exists that their use in practice is not supported by high-quality evidence.

OBJECTIVES

To assess the effect of feeding preterm infants with hydrolysed formula (versus standard cow's milk formulas) on the risk of feed intolerance, necrotising enterocolitis, and other morbidity and mortality in preterm infants.

SEARCH METHODS

We used the standard Cochrane Neonatal search strategy including electronic searches of the Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 4), Ovid MEDLINE, Ovid Embase, and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (to April 2017), as well as conference proceedings and previous reviews.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials that compared feeding preterm infants with protein hydrolysate versus standard (non-hydrolysed) cow's milk formula.

DATA COLLECTION AND ANALYSIS

Two review authors assessed trial eligibility and risk of bias and extracted data independently. We analysed treatment effects as described in the individual trials and reported risk ratios and risk differences for dichotomous data, and mean differences for continuous data, with respective 95% confidence intervals (CI). We used a fixed-effect model in meta-analyses and explored potential causes of heterogeneity in sensitivity analyses. We assessed quality of evidence at the outcome level using the GRADE approach.

MAIN RESULTS

We identified 11 trials for inclusion in the review. All trials were small (total participants 665) and had various methodological limitations including uncertainty about methods to ensure allocation concealment and blinding. Most participants were clinically stable preterm infants of gestational age less than about 34 weeks or birth weight less than about 1750 g. Fewer participants were extremely preterm, extremely low birth weight, or growth-restricted. Most trials found no effects on feed intolerance assessed variously as mean prefeed gastric residual volume, incidence of abdominal distention or other concerning gastrointestinal signs, or time taken to achieve full enteral feeds (meta-analysis was limited because studies used different measures). Meta-analysis found no effect on the risk of necrotising enterocolitis (typical risk ratio 1.10, 95% CI 0.36 to 3.34; risk difference 0.00, 95% CI -0.03 to 0.04; 5 trials, 385 infants) (low quality evidence; downgraded for imprecision and design weaknesses).

AUTHORS' CONCLUSIONS

The identified trials provide only low quality evidence about the effects of feeding preterm infants with protein hydrolysate versus standard formula. The existing data did not support conclusions that feeding with protein hydrolysate affects the risk of feed intolerance or necrotising enterocolitis. Further large, pragmatic trials are needed to provide more reliable and precise estimates of effectiveness and cost-effectiveness.

WITHDRAWN: Infant formulas containing hydrolysed protein for prevention of allergic disease and food allergy

BACKGROUND

Allergy is common and may be associated with foods, including cow's milk formula (CMF). Formulas containing hydrolysed proteins have been used to treat infants with allergy. However, it is unclear whether hydrolysed formulas can be advocated for prevention of allergy in infants.

OBJECTIVES

To compare effects on allergy and food allergy when infants are fed a hydrolysed formula versus CMF or human breast milk. If hydrolysed formulas are effective, to determine what type of hydrolysed formula is most effective, including extensively or partially hydrolysed formula (EHF/PHF). To determine which infants at low or high risk of allergy and which infants receiving early, short-term or prolonged formula feeding may benefit from hydrolysed formulas.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group supplemented by cross referencing of previous reviews and publications (updated August 2016).

SELECTION CRITERIA

We searched for randomised and quasi-randomised trials that compared use of a hydrolysed formula versus human milk or CMF. Trials with ≥ 80% follow-up of participants were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

We independently assessed eligibility of studies for inclusion, methodological quality and data extraction. Primary outcomes included clinical allergy, specific allergy and food allergy. We conducted meta-analysis using a fixed-effect (FE) model.

MAIN RESULTS

Two studies assessed the effect of three to four days' infant supplementation with an EHF whilst in hospital after birth versus pasteurised human milk feed. Results showed no difference in infant allergy or childhood cow's milk allergy (CMA). No eligible trials compared prolonged hydrolysed formula versus human milk feeding.Two studies assessed the effect of three to four days infant supplementation with an EHF versus a CMF. One large quasi-random study reported a reduction in infant CMA of borderline significance among low-risk infants (risk ratio (RR) 0.62, 95% confidence interval (CI) 0.38 to 1.00).Prolonged infant feeding with a hydrolysed formula compared with a CMF was associated with a reduction in infant allergy (eight studies, 2852 infants; FE RR 0.82, 95% CI 0.72 to 0.95; risk difference (RD) -0.04, 95% CI -0.08 to -0.01; number needed to treat for an additional beneficial outcome (NNTB) 25, 95% CI 12.5 to 100) and infant CMA (two studies, 405 infants; FE RR 0.38, 95% CI 0.16 to 0.86). We had substantial methodological concerns regarding studies and concerns regarding publication bias, as substantial numbers of studies including those in high-risk infants have not comprehensively reported allergy outcomes (GRADE quality of evidence 'very low').Prolonged infant feeding with a hydrolysed formula compared with a CMF was not associated with a difference in childhood allergy and led to no differences in specific allergy, including infant and childhood asthma, eczema and rhinitis and infant food allergy. Many of the analyses assessing specific allergy are underpowered.Subroup analyses showed that infant allergy was reduced in studies that enrolled infants at high risk of allergy who used a hydrolysed formula compared with a CMF; used a PHF compared with a CMF; used prolonged and exclusive feeding of a hydrolysed formula compared with a CMF; and used a partially hydrolysed whey formula compared with a CMF. Studies that enrolled infants at high risk of allergy; used a PHF compared with a CMF; used prolonged and exclusive feeding of a hydrolysed formula compared with a CMF; and used a partially hydrolysed whey formula compared with a CMF found a reduction in infant CMA.

AUTHORS' CONCLUSIONS

We found no evidence to support short-term or prolonged feeding with a hydrolysed formula compared with exclusive breast feeding for prevention of allergy. Very low-quality evidence indicates that short-term use of an EHF compared with a CMF may prevent infant CMA.In infants at high risk of allergy not exclusively breast fed, very low-quality evidence suggests that prolonged hydrolysed formula feeding compared with CMF feeding reduces infant allergy and infant CMA. Studies have found no difference in childhood allergy and no difference in specific allergy, including infant and childhood asthma, eczema and rhinitis and infant food allergy.Very low-quality evidence shows that prolonged use of a partially hydrolysed formula compared with a CMF for partial or exclusive feeding was associated with a reduction in infant allergy incidence and CMA incidence, and that prolonged use of an EHF versus a PHF reduces infant food allergy.

Infant formulas containing hydrolysed protein for prevention of allergic disease and food allergy

BACKGROUND

Allergy is common and may be associated with foods, including cow's milk formula (CMF). Formulas containing hydrolysed proteins have been used to treat infants with allergy. However, it is unclear whether hydrolysed formulas can be advocated for prevention of allergy in infants.

OBJECTIVES

To compare effects on allergy and food allergy when infants are fed a hydrolysed formula versus CMF or human breast milk. If hydrolysed formulas are effective, to determine what type of hydrolysed formula is most effective, including extensively or partially hydrolysed formula (EHF/PHF). To determine which infants at low or high risk of allergy and which infants receiving early, short-term or prolonged formula feeding may benefit from hydrolysed formulas.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group supplemented by cross referencing of previous reviews and publications (updated August 2016).

SELECTION CRITERIA

We searched for randomised and quasi-randomised trials that compared use of a hydrolysed formula versus human milk or CMF. Trials with ≥ 80% follow-up of participants were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

We independently assessed eligibility of studies for inclusion, methodological quality and data extraction. Primary outcomes included clinical allergy, specific allergy and food allergy. We conducted meta-analysis using a fixed-effect (FE) model.

MAIN RESULTS

Two studies assessed the effect of three to four days' infant supplementation with an EHF whilst in hospital after birth versus pasteurised human milk feed. Results showed no difference in infant allergy or childhood cow's milk allergy (CMA). No eligible trials compared prolonged hydrolysed formula versus human milk feeding.Two studies assessed the effect of three to four days' infant supplementation with an EHF versus a CMF. One large quasi-random study reported a reduction in infant CMA of borderline significance among low-risk infants (risk ratio (RR) 0.62, 95% confidence interval (CI) 0.38 to 1.00).Prolonged infant feeding with a hydrolysed formula compared with a CMF was associated with a reduction in infant allergy (eight studies, 2852 infants; FE RR 0.82, 95% CI 0.72 to 0.95; risk difference (RD) -0.04, 95% CI -0.08 to -0.01; number needed to treat for an additional beneficial outcome (NNTB) 25, 95% CI 12.5 to 100) and infant CMA (two studies, 405 infants; FE RR 0.38, 95% CI 0.16 to 0.86). We had substantial methodological concerns regarding studies and concerns regarding publication bias, as substantial numbers of studies including those in high-risk infants have not comprehensively reported allergy outcomes (GRADE quality of evidence 'very low').Prolonged infant feeding with a hydrolysed formula compared with a CMF was not associated with a difference in childhood allergy and led to no differences in specific allergy, including infant and childhood asthma, eczema and rhinitis and infant food allergy. Many of the analyses assessing specific allergy are underpowered.Subroup analyses showed that infant allergy was reduced in studies that enrolled infants at high risk of allergy who used a hydrolysed formula compared with a CMF; used a PHF compared with a CMF; used prolonged and exclusive feeding of a hydrolysed formula compared with a CMF; and used a partially hydrolysed whey formula compared with a CMF. Studies that enrolled infants at high risk of allergy; used a PHF compared with a CMF; used prolonged and exclusive feeding of a hydrolysed formula compared with a CMF; and used a partially hydrolysed whey formula compared with a CMF found a reduction in infant CMA.

AUTHORS' CONCLUSIONS

We found no evidence to support short-term or prolonged feeding with a hydrolysed formula compared with exclusive breast feeding for prevention of allergy. Very low-quality evidence indicates that short-term use of an EHF compared with a CMF may prevent infant CMA.In infants at high risk of allergy not exclusively breast fed, very low-quality evidence suggests that prolonged hydrolysed formula feeding compared with CMF feeding reduces infant allergy and infant CMA. Studies have found no difference in childhood allergy and no difference in specific allergy, including infant and childhood asthma, eczema and rhinitis and infant food allergy.Very low-quality evidence shows that prolonged use of a partially hydrolysed formula compared with a CMF for partial or exclusive feeding was associated with a reduction in infant allergy incidence and CMA incidence, and that prolonged use of an EHF versus a PHF reduces infant food allergy.

Use of extensively hydrolysed formula for refeeding neonates postnecrotising enterocolitis: a nationwide survey-based, cross-sectional study

OBJECTIVE

To evaluate the prevalence of and reasons for using extensively hydrolysed formulas (EHFs) of cow's milk proteins in the French neonatal units as well as the modality of their prescription for refeeding infants recovering from necrotising enterocolitis (NEC).

METHODS

A multicentre nationwide cross-sectional study using a questionnaire to address the prevalence of use and the reasons for prescribing EHF in hospitalised neonates and to examine the protocols and the actual reasons for their use for refeeding infants in recovery from NEC. The questionnaire was sent to only 1 senior neonatologist in each neonatal unit included in the study.

RESULTS

More than half of the French neonatal units participated in the survey. 91% of the surveyed units used EHF. Of 1969 infants hospitalised on the day the survey was run, 12% were fed on an EHF. 11% of the EHF prescriptions were due to previous NEC. The main reasons for using an EHF to feed infants post-NEC were the absence of human milk (75%) and surgical management of NEC (17%). When given, EHF was mainly prescribed for a period varying between 15 days and 3 months. None of the involved units continued using the EHF after 6 months of age. More than half of the surveyed units acknowledged hospitalising infants for the initiation of weaning EHF but only 21% of them tested these infants for cow's milk allergy.

CONCLUSIONS

The prevalence of EHF use in the French neonatal units is high. Refeeding infants post-NEC is one of the main reasons for such a high prevalence. The main incentive for using an EHF is the absence of human breast milk, either maternal or donor.

Should Partial Hydrolysates Be Used as Starter Infant Formula? A Working Group Consensus

Partially hydrolyzed formulas (pHFs) are increasingly used worldwide, both in the prevention of atopic disease in at-risk infants and in the therapeutic management of infants with functional gastrointestinal manifestations. Because prevention is always preferable to treatment, we reviewed the literature aiming to find an answer for the question whether pHF may be recommended for feeding all infants if breast-feeding is not possible. PubMed and Cochrane databases were searched up to December 2014. In addition, to search for data that remained undetected by the searches, we approached authors of relevant articles and major producers of pHFs asking for unpublished data. Because few data were found, nonrandomized, controlled trials and trials in preterm infants were included as well. Overall, only limited data could be found on the efficacy and safety of pHF in healthy term infants. Available data do not indicate that pHFs are potentially harmful for healthy, term infants. With respect to long-term outcomes, particularly referring to immune, metabolic and hormonal effects, data are, however, nonexistent. From a regulatory point of view, pHFs meet the nutrient requirements to be considered as standard formula for term healthy infants. Cost, which is different from country to country, should be considered in the decision-making process. Based on limited available data, the use of pHF in healthy infants is safe with regard to growth. The lack of data, in particular for metabolic consequences and long-term outcomes, is, however, the basis for our recommendation that health authorities should develop and support long-term follow-up studies. Efficacy and long-term safety data are required before a recommendation of this type of formula for all infants can be made.

Application effect of extensively hydrolyzed milk protein formula and follow-up in preterm children with a gestational age of less than 34 weeks: study protocol for a randomized controlled trial

Background

The average incidence of preterm birth in the world is up to 11.1 %, and deaths of preterm children account for more than 50 % of neonatal deaths. Gastrointestinal function of preterm children with a gestational age less than 34 weeks is immaturely developed. For preterm children who can only be fed with formula due to their mothers’ sickness, choosing a suitable formula can not only meet the high nutritional needs of preterm children, but also solve their low gastrointestinal tolerability, and is thus very important.

Methods/Design

The study is a prospective, randomized, single-blind and controlled clinical trial. Preterm children with a gestational age less than 34 weeks meeting the inclusion criteria who cannot be breastfed will be included. To demonstrate the application effect of extensively hydrolyzed milk protein formula on the target population, preterm children will be randomized into two groups, 185 subjects in each group. The observation group will be fed with extensively hydrolyzed milk protein (100 % whey protein) formula, while the control group will be fed with preterm children’s formula until the children are discharged from the neonatal intensive care unit (NICU). All the formula involved in this study will be from Dumex. After discharge, both groups will be uniformly fed with formula for 0 to 6-month-old infants. For statistical analysis, a chi-square test and Student’s t test will be applied using SAS 9.4.

Discussion

This will be the first randomized controlled clinical study with long-term observation of the growth and development of preterm children during the NICU stay and at 3-month follow-up after discharge from the NICU. Results from this study will be used to determine whether the extensively hydrolyzed formula is more suitable for the low gastrointestinal tolerability of preterm children, and also whether feeding preterm children who are fed with such formula during the NICU stay with ordinary infant formula after discharge from the NICU would affect the normal growth and development of preterm children in the early stage of their lives.

Trial registration

This study was registered with the Chinese Clinical Trial Registry (http://www.chictr.org.cn/) with number ChiCTR-IOR-14005696, on December 22, 2014.

Considerations in meeting protein needs of the human milk-fed preterm infant

Preterm infants provided with sufficient nutrition to achieve intrauterine growth rates have the greatest potential for optimal neurodevelopment. Although human milk is the preferred feeding for preterm infants, unfortified human milk provides insufficient nutrition for the very low-birth-weight infant. Even after fortification with human milk fortifier, human milk often fails to meet the high protein needs of the smallest preterm infants, and additional protein supplementation must be provided. Although substantial evidence exists to support quantitative protein goals for human milk-fed preterm infants, the optimal type of protein for use in human milk fortification remains uncertain. This question was addressed through a PubMed literature search of prospective clinical trials conducted since 1990 in preterm or low-birth-weight infant populations. The following 3 different aspects of protein quality were evaluated: whey-to-casein ratio, hydrolyzed versus intact protein, and bovine milk protein versus human milk protein. Because of a scarcity of current studies conducted with fortified human milk, studies examining protein quality using preterm infant formulas were included to address certain components of the clinical question. Twenty-six studies were included in the review study. No definite advantage was found for any specific whey-to-casein ratio. Protein hydrolyzate products with appropriate formulations can support adequate growth and biochemical indicators of nutrition status and may reduce gastrointestinal transit time, gastroesophageal reflux events, and later incidence of atopic dermatitis in some infants. Plasma amino acid levels similar to those of infants fed exclusive human milk-based diets can be achieved with products composed of a mixture of bovine proteins, peptides, and amino acids formulated to replicate the amino acid composition of human milk. Growth and biochemical indicators of nutrition status are similar for infants fed human milk fortified with human milk protein and bovine milk protein.

Extensive and partial protein hydrolysate preterm formulas

Protein hydrolysate formulas for preterm infants recently have been developed. However, the indications for the use of such formulas are unclear. The aim of this article is to systematically evaluate the effect of protein hydrolysate formulas in the feeding of preterm infants through searching the MEDLINE (1966-August 2006) and Cochrane Library (Issue 4, 2006) databases. There is little evidence to support the use of extensive and partial protein hydrolysate formulas for preterm infants. High quality, long-term trials are required before these formulas should be offered routinely in preference to other types of formula for preterm infants.

Formulas containing hydrolysed protein for prevention of allergy and food intolerance in infants

BACKGROUND

Allergies and food reactions are common and may be associated with foods including adapted cow's milk formula. Formulas containing hydrolysed proteins have been used to treat infants with allergy or food intolerance. However, it is unclear whether hydrolysed formula can be advocated for prevention of allergy and food intolerance in infants without evidence of allergy or food intolerance.

OBJECTIVES

To determine the effect of feeding hydrolysed formulas on allergy and food intolerance in infants and children compared to adapted cow's milk or human breast milk. If hydrolysed formulas are effective, to determine what type of hydrolysed formula is most effective including extensively and partially hydrolysed formulas. To determine which infants benefit, including infants at low or high risk of allergy and infants receiving early, short term or prolonged formula feeding.

SEARCH STRATEGY

The standard search strategy of the Cochrane Neonatal Review Group was used. The review was updated with searches of the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2006), MEDLINE (1966-March 2006), EMBASE (1980-March 2006) and CINAHL (1982-March 2006) and previous reviews including cross references.

SELECTION CRITERIA

Randomised and quasi-randomised trials that compare the use of a hydrolysed infant formula to human milk or cow's milk formula. Trials with >80% follow up of participants were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Eligibility of studies for inclusion, methodological quality and data extraction were assessed independently by each review author. Primary outcomes included clinical allergy, specific allergies and food intolerance. Meta-analysis was conducted using a fixed effects model.

MAIN RESULTS

Two trials compared early, short term hydrolysed formula to human milk feeding. No significant difference in infant allergy or childhood cow's milk allergy (CMA) were reported. No eligible trial compared prolonged hydrolysed formula to human milk feeding. Two trials compared early, short term hydrolysed formula to cow's milk formula feeding. No significant benefits were reported. One large quasi-random study reported a reduction in infant CMA of borderline significance in low risk infants (RR 0.62, 95% CI 0.38, 1.00). Ten eligible studies compared prolonged feeding with hydrolysed formula versus cow's milk formula in high risk infants. Meta-analysis found a significant reduction in infant allergy (seven studies, 2514 infants; typical RR 0.79, 95% CI 0.66, 0.94), but not in the incidence of childhood allergy (two studies, 950 infants; typical RR 0.85, 95% CI 0.69, 1.05). There was no significant difference in infant eczema (eight studies, 2558 infants, typical RR 0.84, 95% CI 0.68, 1.04), childhood eczema incidence (two studies, 950 infants, typical RR 0.83, 95% CI 0.63, 1.10), childhood eczema prevalence (one study, 872 infants; RR 0.66, 95% CI 0.43, 1.02), or infant or childhood asthma, rhinitis and food allergy. One study reported a significant reduction in infants with CMA with confirmed atopy (RR 0.36, 95% CI 0.15, 0.89). Subgroup analysis of trials blinded to formula found no significant difference in infant allergy (four studies, 2156 infants; typical RR 0.87, 95% CI 0.69, 1.08) or childhood allergy incidence (one study, 872 infants; RR 0.91, 95% CI 0.73, 1.14). No eligible trial examined the effect of prolonged hydrolysed formula feeding on allergy beyond early childhood. There is evidence that preterm or low birthweight infants fed a hydrolysed preterm formula have significantly reduced weight gain, but not in other growth parameters (head circumference or length). Studies in term infants report no adverse effects on growth. Subgroup analysis of trials of partially hydrolysed versus cow's milk formula found a significant reduction in infant allergy (six studies, 1391 infants; typical RR 0.79, 95% CI 0.65, 0.97) but not childhood allergy, or infant or childhood asthma, eczema or rhinitis. Methodological concerns were the same as for the overall analysis. Analysis of trials of extensively hydrolysed formula versus cow's milk formula found no significant differences in allergy or food intolerance. Infants fed extensively hydrolysed formula compared with partially hydrolysed formula had a significant reduction in food allergy (two studies, 341 infants; typical RR 0.43, 95% CI 0.19, 0.99), but there was no significant difference in all allergy or any other specific allergy incidence. Comparing extensively hydrolysed casein containing formula with cow's milk formula, one study (431 infants) reported a significant reduction in childhood allergy incidence (RR 0.72, 95% CI 0.53, 0.97). Meta-analysis found a significant reduction in infant eczema (three studies, 1237 infants; typical RR 0.71, 95% CI 0.51, 0.97). One study reported a significant reduction in childhood eczema incidence (RR 0.66, 95% CI 0.44, 0.98) and prevalence (RR 0.50, 95% CI 0.27, 0.92).

AUTHORS' CONCLUSIONS

There is no evidence to support feeding with a hydrolysed formula for the prevention of allergy compared to exclusive breast feeding. In high risk infants who are unable to be completely breast fed, there is limited evidence that prolonged feeding with a hydrolysed formula compared to a cow's milk formula reduces infant and childhood allergy and infant CMA. In view of methodological concerns and inconsistency of findings, further large, well designed trials comparing formulas containing partially hydrolysed whey, or extensively hydrolysed casein to cow's milk formulas are needed.

Hydrolysed milk in preterm infants: an open problem

AIM

To review knowledge about the role, indications and nutritional adequacy of protein hydrolysate formulas (HF) in the preterm newborn.

METHODS

A review of the available literature was carried out.

RESULTS

No data support the use of HF for atopy prevention. HF could have a positive role in the early feeding of very-low-birthweight infants, but several concerns exist about their nutritional adequacy.

CONCLUSION

Further investigations addressing protein and mineral metabolism as well as long-term effects, including neurodevelopment, are needed.

Higher urinary excretion of essential amino acids in preterm infants fed protein hydrolysates

AIM

Protein hydrolysates have been introduced in preterm formulae, but it is not clear whether they are needed for the feeding of preterm infants. We designed a randomized, controlled trial to test the effects of a preterm formula with hydrolysed cow's milk proteins on short-term growth and urinary and plasma amino acids levels.

METHODS

Infants with a birthweight < or = 1750 g and gestational age < or = 34 wk fed a conventional preterm infant formula (formula B) or a hydrolysed formula (formula A). Weight was measured daily; length, head circumference, mid-arm circumference and total skinfold thickness were measured weekly. Blood and urine were analysed for amino acid concentrations at start, 14 and 28 d.

RESULTS

Twenty-one infants met the criteria for randomization. The daily feeding volumes were: formula A 172.8 +/- 5.6 vs formula B 170.1 +/- 2.8 ml/kg/d. Infants fed with formula A showed slower weight gain (17.4 +/- 3.4 vs 20.5 +/- 3.3 g/kg/d; p = 0.045) and lower mean change in Z-scores for weight (-0.18 +/- 0.16 vs 0.00 +/- 0.09; p = 0.009) and for head circumference (-0.06 +/- 0.13 vs 0.06 +/- 0.13; p = 0.049). After 14 d, infants receiving formula A had statistically significant higher urinary levels of essential amino acids compared to infants receiving formula B.

CONCLUSION

Our results support the hypothesis of less nutritional value of hydrolysed versus conventional preterm formulae. Higher renal excretion of essential amino acids may be one of the mechanisms involved. These findings must be confirmed by further studies with larger sample sizes and protein hydrolysates with different degrees of hydrolysis.

Hydrolysis of casein accelerates gastrointestinal transit via reduction of opioid receptor agonists released from casein in rats

BACKGROUND

Protein hydrolysate accelerates gastrointestinal transit (GIT) and feeding advancement in preterm infants compared to native protein. In rat pups, opioid receptor agonists released from casein during digestion such as beta-casomorphins slow down GIT. We hypothesized that hydrolysis of casein reduces the opioid activity released during digestion thereby accelerating GIT compared to native casein.

OBJECTIVE

The aim of the present study was to investigate whether casein hydrolysate accelerates GIT compared to native casein and whether pretreatment with naloxone, an opioid receptor blocker, abolishes this difference in rat pups.

METHODS

In a randomized controlled trial following a 2 x 2 factorial design, 216 female Wistar rat pups were fed with pellets based on hydrolyzed or native casein. After pretreatment with naloxone or normal saline, carmine red was administered by oro-gastric gavage as a tracer for GIT velocity measurement. Four hours later the animals were sacrificed, their intestine was removed and the length of the colon from the cecocolonic junction to the anus was measured. GIT was recorded as percentage of the total colonic length (percentage of colonic transit) passed by carmine red. Data were given as mean +/- SD.

RESULTS

GIT was significantly higher with hydrolyzed casein compared to native casein formula (77.4 +/- 17 and 51.2 +/- 20%), but there was no difference after naloxone pretreatment (77.1 +/- 16 and 76.5 +/- 17%).

DISCUSSION

The present data suggest that hydrolysis of casein accelerates GIT via reduction of opioid activity released during digestion. Further studies are required to investigate to which extent these rat pub data apply to preterm infants.

Effect of protein hydrolysis on the dialysability of amino acids and minerals in infant formulas

The objectives of this study were to evaluate the dialysed quantities of amino acids and minerals (calcium, phosphorus, magnesium, iron and zinc) in two types of infant formulas, one with a basis of native cow milk proteins and the other highly hydrolysed, to evaluate the possible application of Miller's in vitro method in amino acid and mineral availability studies. The percentage of dialysis differed between proteins. The hydrolysis treatment applied to the proteins significantly increased the dialysis percentage of almost all the amino acids. The dialysability of all the minerals was statistically greater in the formula made with a basis of hydrolysed proteins. Miller's method was seen to be of use for showing the effect which the hydrolysis treatment has on the availability of amino acids. Despite its limitations of having to be carried out in vitro, the study suggests that the nutritional value in relation with amino acids, minerals and trace elements differs between the both types of formulas.

Hydrolyzed protein accelerates feeding advancement in very low birth weight infants

BACKGROUND

Feeding intolerance is common in very low birth weight (VLBW; <1500 g) infants. Hydrolyzed protein preterm infant formula (HPF) has been shown to accelerate the gastrointestinal transit of formula. The aim of this study was to investigate whether HPF improves early feeding tolerance compared with standard preterm infant formula (SPF). We hypothesized that HPF would accelerate early enteral feeding advancement.

METHODS

Primary outcome was the time from initiation of milk feeds until full feeds (150 mL/kg birth weight/d) were achieved in infants who received <10% human milk (HM) to exclude HM as a confounder. Because the availability of HM was not predictable at the time of enrollment, all eligible VLBW infants (n = 129) were randomly assigned in a randomized, controlled trial to receive HPF or SPF if HM was not available. Infants who received >10% HM (n = 42) were excluded. Milk bolus feeding every 2 to 3 hours was started at the discretion of the attending physician and advanced by 16 mL/kg/d. Preprandial gastric residuals were tolerated up to 5 mL/kg; otherwise, feedings were reduced or withheld. Data are shown as median (5th and 95th percentile).

RESULTS

Forty-six and 41 (HPF vs SPF) infants received <10% HM. There was no significant difference with regard to birth weight, gestational age, and onset of milk feeds (day 3 [1-8] vs 4 [2-6]). The time from initiation of milk feeds to full feeds was significantly shorter with HPF feeding (10 [9-27] vs 12 [9-28] days).

CONCLUSION

HPF improved the feeding tolerance and enabled a more rapid establishment of full enteral feeding in VLBW infants compared with SPF.

Nutritional efficacy of preterm formula with a partially hydrolyzed protein source: a randomized pilot study

BACKGROUND

Decreased nitrogen levels, calcium intestinal absorption rates, and plasma amino acid imbalances were reported for preterm infants who were fed partially hydrolyzed preterm formulas. In this pilot study, we evaluated a new formula with modified nitrogen and calcium sources.

METHODS

During their second week of life, 16 preterm infants were randomly assigned to one of two groups: 9 were fed the new partially hydrolyzed formula and 7 were fed a conventional formula. Nutrient balance was performed at the end of the first month of life. Amino acid concentrations and anthropometric parameters were measured at theoretical term.

RESULTS

Birth weight and gestational age (mean +/- SD) were similar in the two groups (28.9 +/- 7.0 weeks and 1183 +/- 242 g vs. 27.7 +/- 1.0 weeks and 1139 +/- 162 g). Median nitrogen absorption rates (85% vs. 89%; P = 0.03) and biological values (59% vs. 69%; P = 0.13) were lower for infants who were fed the new formula than for those fed the conventional formula. After correction for difference in nitrogen intake, there was no significant difference in nitrogen retained between the two groups (P = 0.11). Plasma amino acid concentrations were also similar in the two groups. Median calcium absorption tended to be higher in the new-formula group than in the conventional-formula group (54% vs. 45%, P = 0.19). At theoretical term, infants fed the conventional formula were heavier than infants fed the new formula (3559 +/- 362 g vs. 3193 +/- 384 g, P = 0.04).

CONCLUSIONS

Because nitrogen content is 10% higher in hydrolyzed-protein formula than in entire-protein formula, appropriate nitrogen retention, plasma amino acid profile, and mineral use can be achieved with the new partially hydrolyzed formula. Further studies with larger groups are needed to evaluate the effect on growth.

Extensive and partial protein hydrolysate preterm formulas: the effect on growth rate, protein metabolism indices, and plasma amino acid concentrations

BACKGROUND

The use of protein hydrolysate preterm formulas is restricted because data on their nutritional adequacy are scarce. The authors evaluated the rate of growth and indices of protein metabolism in low-birth weight infants fed extensive and partial protein hydrolysate preterm formula followed for 12 weeks.

METHODS

A total of 61 low-birth weight infants were assigned randomly to receive extensive protein hydrolysate preterm formula (EH: n = 16), partial protein hydrolysate preterm formula (PH: n = 15), and standard preterm formula (SF; n = 15), or were fed their own mother's fortified breast milk (FBM; n = 15). The infants were investigated at study entry, and at 4, 8, and 12 weeks after study entry.

RESULTS

There were no differences with respect to growth rate (weight gain, increments in length and head circumference), urea, albumin, prealbumin, transferrin, and plasma amino acid concentrations (except for tyrosine on a single occasion) according to the degree of hydrolysis. There were also no differences between groups fed hydrolyzed formulas and SF. However, several differences were found when EH and PH were compared with FBM. Weight gain from the entry to 12 weeks, serum urea at 12 weeks, and total plasma essential amino acids at 8 weeks were significantly higher in groups fed EH and PH than in those fed FBM. In addition, valine was significantly higher in groups fed PH (P < 0.05) than in the group fed FBM at 8 and 12 weeks, tyrosine was higher in EH and PH in comparison with FBM at 4 weeks, and in PH versus FBM at 12 weeks after study entry.

CONCLUSIONS

This study suggests that experimental EH and PH are at least nutritionally equivalent to SFs.

Infant feeding: a critical look at infant formulas

Commercially available infant formulas serve as the best alternative to human milk when breastfeeding is not possible. Infant formulas are designed specifically to mimic the composition of human milk or the functional aspects of human milk feeding. This review highlights the issues related to the composition of infant formulas. The most hotly debated issue currently is whether to add long-chain polyunsaturated fatty acids to infant formulas. Other controversial topics include the safety and efficacy of soy-based protein formulas, protein quantity and quality as they relate to the infant's nutritional needs and feeding tolerance, and the replacement of lactose with other carbohydrate sources for specialized infant formulas. Recent modifications in the fat blend of infant formulas have led to improved fat digestibility. However, the full spectrum of benefits associated with the addition of nucleotides awaits further study. Modifications to infant formulas are made when the preponderance of scientific evidence suggests that the compositional change will better meet the nutritional needs of the infant.