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.     

Protein intake in early infancy: effects on plasma amino acid concentrations, insulin metabolism, and growth

The effects of different protein intakes on wt gain, insulin secretion, and plasma concentrations of amino acids have been evaluated in a prospective study involving 30 normal term infants. The infants were studied from 4.0 to 6.0 mo of age. Ten infants were breast-fed (BF), the others were randomly divided into two groups of 10 infants. One group was fed a formula containing 1.3 g protein/100 mL (F 1.3), the other a formula with 1.8 g protein/100 mL (F 1.8). The formulas were isocaloric (72 kcal/100 mL), and the fat concentrations were 3.5 g/100 mL (F 1.3) and 3.2 g/100 mL (F 1.8). All infants received the same supplementary foods. The urinary C-peptide excretion in the infants fed the F 1.8-formula was 4.4 +/- 2.1 nmol/mmol creatinine or 19.4 +/- 12.9 nmol/m2, significantly higher than that in the infants fed the F 1.3-formula (2.6 +/- 1.5 and 7.9 +/- 5.1) or the BF infants (1.7 +/- 1.4 and 6.3 +/- 6.0). Gain in wt was 18.0 +/- 4.3, 19.9 +/- 3.9, 22.8 +/- 1.6 g/kg/wk and corresponded to protein intakes of 1.3 +/- 0.2, 1.9 +/- 0.3, and 2.6 +/- 0.2 g/kg/d, in the BF, F 1.3, and F 1.8 groups, respectively. Gain in length was 6.7 +/- 1.8 (BF-group), 6.2 +/- 2.5 (F 1.3-group), and 7.6 +/- 2.2 (F 1.8-group) mm/m/wk. Wt gain correlated with urinary C-peptide excretion at 6.0 mo (r = 0.51, p less than 0.01) and with protein intake (r = 0.43, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Growth, serum biochemistries, and amino acids of term infants fed formulas with amino acid and protein concentrations similar to human milk

We tested the hypothesis that amino acid intake from infant formulas modified to be similar to human milk would result in indices of protein metabolism more like those in human milk-fed infants. Formula-fed infants received for 12 weeks one of three isocaloric formulations of a whey-adapted formula that differed in protein concentration: 11, 13, or 15 g/L. Infants consumed similar volumes of formula or human milk. Serum urea nitrogen concentrations reflected the protein content of the diets. Plasma indices of protein nutritional status were normal and did not differ among groups. Growth rates of all infants were normal and similar. Serum indicators of protein nutritional status varied with age, which made comparisons of formula-fed infants with human milk-fed infants difficult. Plasma concentrations of leucine and isoleucine at 4 weeks of age were higher in infants fed the formula containing 15 g protein/L when compared with those of infants fed the other two formulas or human milk. At 8 and 12 weeks of age, all formula-fed infants had plasma amino acid profiles that did not differ significantly from each other except for isoleucine, which was lower in the 11-g/L group. We found that providing formulas with an amino acid pattern similar to that of human milk did not produce a plasma amino acid pattern identical to that of the breast-fed infant. This observation suggests that other factors, such as the hormonal response to feeding, differing nutritional bioavailability of amino acids from human and bovine milk proteins, and the changing quantity and type of amino acids with advancing lactation, influence plasma amino acid concentrations.     

Milk protein intake in the term infant. II. Effects on plasma amino acid concentrations

The response of plasma amino acids to two bovine protein formulas with different protein content (1.6 and 1.2 g/100 ml containing 60% whey proteins and 40% caseins) was measured in term infants. These two groups of infants were compared with a group of infants that were breast-fed; all infants were fed ad libitum. Concentrations of threonine, valine and total branched chain amino acids reflected the amount of protein provided. Thus, the concentrations were higher in the higher protein formula infants from the second week of the study. In the low protein formula infants these amino acids were lower but differed from the infants on breast milk at eight and twelve weeks. Concentration of taurine was lower in the formula fed infants than they were in breast-fed infants at the end of the study. The valine/glycine ratio in the low protein formula group was lower than in the breast-fed group for the first four weeks of the study. After this time it was equal to that of the breast-fed group. These differences in plasma amino acid concentrations give further evidence that formulas now in common use for term infants provide a protein intake in excess of protein requirements after the first months of life.     

Postprandial plasma amino acids in preterm infants: influence of the protein source

Preprandial plasma amino acid concentrations have been used extensively as a marker of the nutritional value of dietary proteins in preterm infants. This study investigated the postprandial plasma amino acid profiles of preterm infants fed with different dietary proteins at similar protein intakes during the first weeks of life. In 12 preterm infants, pre- and postprandial plasma amino acid concentrations were measured before the removal of an indwelling central venous catheter placed for parenteral nutrition. All infants received breast milk until the time of study. At the start day of the study, infants were randomized to receive a test meal of 10 ml/kg, either of breast milk fortified with breast milk protein to reach a protein content of 2.0 g/dl or of a bovine milk preterm formula with a protein content of 2.0 g/dl (whey/casein ratio 60/40). Five samples of 100 microl blood were obtained immediately before and 15, 30, 45 and 60 min after the test meal. The plasma amino acid analysis was performed by a reversed-phase high-performance liquid chromatography based on o-phthaldialdehyde/2-mercaptoethanol pre-column derivatization. In both groups, the plasma amino acid concentrations increased within the first 30 min and the levels did not return to the preprandial baseline during the observation period. Fifteen minutes after the test meal, the plasma levels of all essential amino acids with the exception of histidine were higher in the bovine milk formula fed infants than in the fortified breast milk fed infants. The sum of plasma essential amino acid levels found in the formula fed infants were significantly (p < 0.05) higher than the levels found in the fortified breast milk fed infants at 15, 30 and 45 min. The kinetics of individual amino acids were influenced by the different quality of the protein even when the intakes in the groups were similar, as demonstrated for histidine and phenylalanine. The data indicate that postprandial plasma amino acid concentrations depend significantly on the dietary amino acid source and cannot simply be calculated from the amino acid composition of dietary proteins. Therefore, postprandial plasma amino acid concentrations should be included in the nutritional evaluation of dietary proteins in preterm infants.     

Plasma amino acid and protein concentrations in infants fed human milk or a whey protein hydrolysate formula during the first month of life

The aim of the study was to compare growth parameters, biochemical indices of protein metabolism and plasma amino acid concentrations in infants fed either human milk ( n = 12) or a whey protein hydrolysate formula ( n = 13) during the first month of life. Growth and gain in skin fold thickness were similar in both groups whereas serum protein concentration was significantly decreased (57.4 ± 3.9 versus 61.2 ± 2.9 g/l) in the infants fed the whey hydrolysate formula. The discrepancies between the plasma amino acid pattern of the whey hydrolysate formula group and that of the human milk group lessened during the first month. Nevertheless, at a mean age of 33 days the plasma threonine concentration remained twice as high and the plasma tyrosine, phenylalanine and proline concentrations were Significantly lower in the whey hydrolysate formula group than in the human milk group. Thus, compared with breast-fed infants, growth and most of the biological indices of protein metabolism were satisfactory in infants fed during the first month of life on a whey protein hydrolysate formula. Nevertheless, the decrease in total plasma protein concentration needs to be confirmed in a larger cohort of infants. In addition, further research is necessary to investigate the possible ways of reducing the hyperthreoninemia and preventing other plasma amino acid disturbances since it would be desirable to obtain plasma amino acid levels similar to those of breast-fed infants.     

Minimum protein intake for the preterm neonate determined by protein and amino acid kinetics

Lower limits of protein needs in prematurely born neonates have not been adequately studied, yet providing protein in amounts maximizing accretion without excess is a goal in these infants' nutritional care. We hypothesized that with the use of amino acid oxidation methodology, it would be possible to define minimum protein requirement. Our objective was to investigate protein kinetics during short-term changes in protein intake by measurement of nitrogen balance and amino acid flux and oxidation using [(15)N]glycine, [(13)C]phenylalanine, and [(13)C]leucine tracers. Protein kinetics were examined in 21 preterm infants (gestational age: 29 +/- 3 wk; birth weight: 1091 +/- 324 g) at five protein intakes (1.0, 1.5, 2.0, 2.5, and 3.0 g x kg(-1) x d(-1)) with 1 d of adaptation to the test intakes. From nitrogen balance data, a protein need of 0.74 g x kg(-1 x -1) was estimated to achieve zero balance. For all three amino acids, flux and oxidation estimates were not different across protein intakes. Whole-body protein synthesis and breakdown estimates from [(15)N]ammonia data were 14.6 +/- 3.4 and 14.4 +/- 4.1 g x kg(-1) x d(-1), respectively. Glycine flux (680 +/- 168 micromol x kg(-1) x h(-1)) was greater than leucine flux (323 +/- 115 micromol x kg(-1) x h(-1)), which was greater than phenylalanine flux (84.3 +/- 35.2 micromol x kg(-1) x h(-1)). Leucine oxidation (36.7 +/- 15.6 micromol x kg(-1) x h(-1)) was also greater than phenylalanine oxidation (6.64 +/- 4.41 micromol x kg(-1) x h(-1)). Infants in our study were able to adapt to short-term changes in protein intake with little consequence to the overall whole-body protein economy, as measured by the three test amino acids.     

Milk protein quality in low birth weight infants: effects of protein-fortified human milk and formulas with three different whey-to-casein ratios on growth and plasma amino acid profiles.

Growth rates (weight, length, and head circumference) and selected biochemical indexes of protein metabolism (serum urea, acid-base status, and plasma amino acid concentrations) were determined in low birth weight (LBW) infants appropriate for gestational age (birth weight less than 1,650 g) fed three formulas differing only in the whey-to-casein ratios: 60/40, 50/50, and 35/65. A group of infants fed exclusively human milk protein (HMP)-fortified human milk was used as a control. All diets provided similar daily protein and energy intakes, which were 3.5 g/kg and 122 kcal/kg in the human milk-fed infants and 3.3 g/kg and 121 kcal/kg in the formula-fed infants. Neither weight gain nor rate of growth in length and head circumference differed between the feeding groups and reached intrauterine or better rates in all groups. Values for serum urea and acid-base status were normal and also did not differ among the groups. At the end of the study, plasma threonine concentrations were significantly higher in all formula-fed infants than in the infants fed human milk. The highest plasma threonine concentration was found in the infants receiving the whey-predominant formula. Plasma concentrations of valine, methionine, and phenylalanine were also significantly higher in all formula-fed groups when compared with the human milk group. Plasma total essential amino acid concentrations were also significantly higher in the formula-fed infants than in the human milk fed. The results show that protein quality does not affect growth rate or biochemical indexes of metabolic tolerance in LBW infants fed adequate protein and energy intakes.(ABSTRACT TRUNCATED AT 250 WORDS)     

早期营养支持策略对早产儿生长和代谢的影响

目的 探讨早期营养支持策略对早产儿生长和代谢的影响.方法 回顾性分析我院2005-2007年(A组82例)和2008-2010年(B组82例)出生体重≤1800 g、无先天畸形、住院2周以上、存活出院早产儿的临床资料,比较两组出生时一般情况、肠内外营养摄入、体格增长及血生化指标.结果 与A组相比,B组早产儿应用氨基酸、脂肪乳剂更早[氨基酸:(1.8±0.4)天比(2.1±0.9)天,脂肪乳:(2.2±0.6)天比(2.6±1.6)天],起始剂量更高[氨基酸:(1.4±0.5)g/(kg·d)比(0.8±0.3)g/(kg·d),脂肪乳:(0.9±0.2)g/(kg·d)比(0.6±0.3)g/(kg·d)],且开奶时间早(1天比2天),肠内热卡达到100 kcal/(kg·d)的日龄更早(20天比25天),第7天摄入奶量明显增多(45 ml/天比22 ml/天),母乳喂养及混合喂养率明显增加(56.1%比40.0%),肠外营养时间缩短(24天比27天),体重和身长增长速度更快[体重:(22.6±3.3)g/(kg·d)比(18.6±4.4)g/(kg·d),身长:(1.1±0.6)cm/周比(0.8±0.4)cm/周],出院时宫外生长迟缓发生率降低(58.5%比72.0%),住院时间缩短(30天比35天),血白蛋白、前白蛋白、尿素氮、血磷水平明显增高[白蛋白:(34.2±2.8) g/L比(31.8±2.9)g/L,前白蛋白:(112.0±25.0)mg/L比(89.0±19.0)mg/L,尿素氮:(4.1±2.1)mmol/L比(3.3±1.8)mmol/L,血磷:(2.0±0.5) mmol/L比(1.8±0.5)mmol/L],总胆汁酸和碱性磷酸酶明显降低[总胆汁酸:(25.1±19.7)μmol/L比(38.6±25.2)μmol/L,碱性磷酸酶:(315.4±120.0)U/L比(471.1±202.3)U/L],差异均有统计学意义(P<0.05).结论 早期更积极的营养支持策略能促进早产儿的生长,减少宫外生长迟缓的发生,缩短住院时间,改善营养状况.     

Soybean oil emulsion administration during parenteral nutrition in the preterm infant: effect on essential fatty acid, lipid, and glucose metabolism

To examine the effect of a soybean oil emulsion on essential fatty acid, lipid, and glucose metabolism, preterm infants were randomized to receive 0.5 g/kg/d lipid for 5 days (n = 10, group 1) or 0.5 increased to 2.0 g/kg/d over 5 days (n = 11, group 2). Triene/tetraene ratios did not change in group 1, but decreased in group 2. In both groups, plasma phospholipid linoleate (percent and micrograms per milliliter) increased, the increase being greater in group 2. In both groups, percent content of arachidonate and 5,8,11-eicosatrienoate decreased, and that of oleate remained unchanged. In contrast, absolute content of arachidonate and oleate tended to increase, and that of 5,8,11-eicosatrienoate remained unchanged. At a lipid intake of 0.5 g/kg/d, no infants had hyperlipemia. When lipid intake exceeded 1.0 g/kg/d, the frequency of hypertriglyceridemia (triglycerides greater than 200 mg/dL) and free fatty acidemia, with the free fatty acid/molar albumin ratio exceeding 6:1, increased. Plasma glycerol increased slightly, but was substantially less than the rise in enzymatically determined triglycerides. Hyperglycemia was self-limiting and did not require alteration in dextrose intake. Thus, (1) infusion of a soybean oil emulsion at 0.5 to 2.0 g/kg/d maintains essential fatty acid status and phospholipid arachidonate concentrations; (2) significant hyperlipemia occurs when lipid intake exceeds 1.0 g/kg/d; (3) hyperglycemia associated with lipid infusion tends to be self-limiting and may not require alteration in lipid or dextrose intake; and (4) enzymatically determined triglycerides may be used to monitor lipid tolerance, provided that allowance is made for a small but systematic overestimation resulting from the rise in plasma glycerol.     

Parenteral nutrition in preterm infants: influence of respiratory treatment and effect of different amino acid compositions

Thirty-three premature infants receiving parenteral nutrition during the first 5 days of life were divided into three groups. Infants in group I (n = 13) received no ventilatory therapy. Those in groups II (n = 10) and III (n = 10) were intubated and artificially ventilated because of hyaline membrane disease, apnea, or other illness. All infants received glucose, amino acids, fat emulsion, and electrolytes in their total parenteral nutrition regimen. Groups I and II were administered a transfer-adapted amino acid solution (Aminoplasmal paed 5%) for their protein supplementation, and group III, a so-called human milk-adapted solution (Aminoven?s 6%). The three groups were compared with respect to amino acid blood level, amino acid excretion, and nitrogen balance. Taurine levels decreased significantly during parenteral nutrition in all three groups. The other amino acids, with a few exceptions, remained within acceptable range. Elevations of serine, proline, and methionine were found in group III after the third day. All three groups exhibited good nitrogen retention. Excretion of amino acids was only about 1%.     

Free amino acid concentrations in plasma, erythrocytes, granulocytes, and lymphocytes in umbilical cord blood, children, and adults

Concentrations of free amino acids were measured concurrently in plasma, erythrocytes, granulocytes, and lymphocytes in umbilical cord blood, neonates, children, and adults. In each age group, the patterns of free amino acids were fairly similar in plasma and erythrocytes except for aspartic acid which was more abundant in erythrocytes. Of the amino acids in granulocytes, 71-77% was taurine; in lymphocytes taurine, aspartic acid, and glutamic acid comprised 35-44%, 18-24%, and 20-28%, respectively, of the total in all age groups. Leukocytes may contribute to the interorgan transport of amino acids to about 10% of the erythrocytes' contribution. Postnatally, the levels of glutamic acid and tyrosine in plasma; threonine plus glutamine, serine plus asparagine, and tyrosine in erythrocytes; histidine in granulocytes; and glutamic acid in lymphocytes were significantly increased (p less than 0.001); while the levels of phenylalanine and lysine in plasma; taurine in erythrocytes; valine and phenylalanine in granulocytes; and threonine plus glutamine, tyrosine, and phenylalanine in lymphocytes were significantly decreased (p less than 0.001). After the neonatal period concentrations of taurine and aspartic acid in erythrocytes, taurine and valine in granulocytes, and tyrosine and phenylalanine in lymphocytes increased gradually with age; while concentrations aspartic acid in plasma, histidine in granulocytes, and glycine in lymphocytes decreased gradually with age. The levels of glycine and valine in plasma, alanine and valine in erythrocytes, serine plus asparagine, glycine, alanine, and tyrosine in granulocytes, and aspartic acid, serine plus asparagine, and alanine in lymphocytes remained constant in all age groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Protein requirements in preterm infants: effect of different levels of protein intake on growth and body composition

This study compares growth and body composition in preterm infants (< or =1750 g birth weight, < or =34 wk gestation) fed three iso-caloric formulas (80 kcal/100 mL) with different protein concentrations (A = 3.3 g/100 kcal, B = 3.0 g/100 kcal, C = 2.7 g/100 kcal). The study began when full enteral feeding (150 mL/kg/d) was established and lasted until term plus 12 wk corrected age (T + 12 wca). Nutrient intake was closely monitored throughout the study; daily during initial hospital stay and following discharge averaged between each clinic visit. Anthropometry and serum biochemistries were determined weekly during initial stay and at each clinic visit. Body composition was measured after hospital discharge and at T + 12 wca. Seventy-seven infants were recruited. No differences were detected in birth/enrollment characteristics between the groups. Protein intake was closely paralleled by changes in serum urea nitrogen and differed between the groups. Infants in group A were heavier and longer and had greater head circumference at discharge, but this was confounded by a slightly older corrected age in this group. There were no significant anthropometric differences at term or T + 12 wca. No differences were detected in body composition between the groups following discharge or at T + 12 wca. An intake of 3.3 g/100 kcal appears safe and may promote increased growth before initial hospital discharge. After discharge, intakes greater than 2.7 g/100 kcal do not appear to offer clear advantage. Further studies are needed to more precisely define protein requirements in these nutritionally at-risk infants.     

Feeding premature infants with human milk or preterm milk formula. Effects on postnatal growth and on circulating concentrations of intermediary metabolites, amino acids, and regulatory peptides

Results of a comprehensive longitudinal study comparing the effects of feeding healthy preterm infants with human milk or a specially adapted formula designed for the preterm infant are reported. 10 healthy infants were given human milk from birth, and 9 similar infants were given a formula which contained 80 kcal, 1.8 g protein, and 4.5 g fat per 100 ml. Anthropometric measurements were made weekly as were routine haematological and biochemical variables together with plasma amino acid and gastrointestinal regulatory peptide levels and metabolic fuel concentrations. Infants receiving the formula demonstrated a significantly greater growth velocity compared with infants receiving human milk. There were no significant differences between the two groups in routine haematological or biochemical variables measured nor in plasma insulin or blood glucose, lactate, pyruvate, or ketone body concentrations. Plasma amino acid profiles, however, did demonstrate some significant differences between the two groups with higher methionine and threonine levels in the formula-fed infants. Plasma motilin, enteroglucagon, neurotensin, cholecystokinin, gastric inhibiting polypeptide, and pancreatic polypeptide levels all demonstrated significant postnatal surges, with significant differences between the two groups in plasma gastric inhibiting polypeptide and pancreatic polypeptide concentrations.     

Growth and plasma amino acid concentrations in very low birthweight infants fed either human milk protein fortified human milk or a whey-predominant formula

In a prospective, study involving 20 VLBW-infants (AGA), divided into two study groups of 10 infants, we have evaluated the effects on growth and metabolism of human milk fortified with ultrafiltrated human milk protein and a whey-predominant (whey/casein = 60/40) formula containing 2 g/dl of protein. The study was initiated at a mean age of 30 days when an oral intake of 180 ml/kg/d was tolerated and continued until a weight of 2 kg was reached. The protein intake in both groups was about 3.7 g/kg/d. All infants in both groups reached intrauterine rates of growth for the age, weight gain 18.0 g/kg/d, and length 1.2 cm/week. BUN, acid-base status, total protein and albumin were normal and similar in the two groups. Plasma levels of threonine, glycine, citrulline and methionine were significantly greater in the formula-fed infants. Taurine and proline had higher concentrations in the protein fortified human milk group. There was good tolerance of protein from both sources but the differences in plasma amino acid profiles suggest that the dietary protein quality in formulas for preterm infants must be further modified, if the goal of formula feeding is to achieve metabolic indices of protein metabolism similar to those found when human milk protein is used.     

Antepartum glucocorticoid treatment: the effect of prednisolone on umbilical blood glucose, plasma free fatty acids and individual free amino acid levels.

Blood glucose, plasma free fatty acid and individual free amino acid levels were measured in the cord blood of preterm newborns whose mothers had received prednisolone treatment to prevent RDS. No significant differences were found in either of the metabolites between the prednisolone treated and the control group of comparable gestational age and birth weight. The results suggest that corticosteroid treatment has no gross adverse effect on fuel homeostasis.