Protein and energy requirements in preterm infants

Although protein and energy requirements in healthy growing and enterally fed infants are relatively well established, the nutritional requirements of extremely low birth weight infants are considerably less certain. New and emerging data in ELBW infants suggest high rates of energy expenditure and protein losses, which results in significant nutritional deficits and high rates of growth failure. Based on the limited and incomplete available data, energy intakes of 125–130 kcal/kg/d and protein intakes of 3.5–4 g/kg/d appear to be necessary to produce normal growth in ELBW infants. Although these intakes may be difficult to achieve in clinical practice, there is clear evidence that aggressive early nutrition can improve growth outcomes in these infants.     

Protein intake affects phenylalanine requirements and growth of infants with phenylketonuria

Growth and metabolic status of 25 infants with PKU were evaluated based on protain intake. Food A-fed infants received a medical food containing 3.12g protein equivalent per 100 kcal and Food B-fed infants received a medical food containing 2.74 g protein equivalent per 100 kcal. Growth percentiles of infants in the Food A group were significantly greater than those for infants in the Food B group at 6 months of age (Food A percentiles: crown-heel length 55, head circumference 60, weight 73. Food B percentiles: crown-heel length 28; head circumference 29, weight 39). At study entrance, only crown-heel length of the two groups differed; Food B infants had a significantly greater mean crown-heel length percentile ( p < 0.05). Mean phenylalanine (PHE) intake was 38% greater by Food A-fed infants than by Food B-fed infants. Plasma PHE concentrations and mean energy intakes of the two groups did not differ. Mean protein intake of Food A-fed infants was greater during the first three months of life and significantly greater ( p < 0.05) during the second three months of life than by Food B-fed infants. Mean protein intake 24% greater than Recommended Dietary Allowances (RDA) was associated with better PHE tolerance and growth than was found when mean protein intake was 9% greater than RDA.     

Postnatal growth failure in preterm infants: recovery of growth and body composition after term

BACKGROUND: Many preterm infants are significantly growth restricted at hospital discharge and are at increased risk for long-term growth failure. AIMS: To compare growth and weight gain composition after term between preterm infants who were growth retarded and those who were not. STUDY DESIGN: An observational longitudinal study was conducted. SUBJECTS: 35 preterm infants who showed growth retardation at term (group 1) and 26 preterm infants who did not (group 2). OUTCOME MEASURES: Growth and body composition were assessed at term and at 1, 2, 3, 4 and 5 months of corrected age. RESULTS: At term, and at 1, 2, and 3 months of corrected age, growth-retarded infants showed significantly lower body weight and fat mass than infants who did not develop growth retardation. The mean energy and protein intakes did not differ significantly between the two groups. Daily increases in body weight and fat mass between term and three months did not differ between the groups. However, during the fourth and fifth months, daily gains of body weight and fat mass were significantly greater in growth-retarded than in non-growth-retarded infants, and as a result, body weight and fat mass were comparable between the two groups at 4 and 5 months of corrected age. CONCLUSIONS: In terms of growth parameters and body composition, growth-retarded preterm infants recovered from postnatal growth failure within the fourth month of corrected age.     

Diet and body composition of preterm infants

There have been few systematic studies of the effects of energy and protein intake on the body composition of preterm infants. Analysis of published studies suggests a roughly inverse relation between energy stored per gram of weight gain (a measure of the fatness of new tissues) and the ratio of protein to energy in the preterm infant's diet. At least within a certain range of energy and protein intakes, a higher protein diet promotes leaner body composition. Studies of the effects of varying the dietary ratio of carbohydrate to fat in preterm infants have shown reduced rates of carbon dioxide production with high-fat diets, fed by either the parenteral or enteral route. The little information available suggests no clear effect of varying the carbohydrate-to-fat ratio on body composition. The mineral content of the body can be influenced by diet. Insufficient intakes of calcium and phosphorus reduce the bone mineral content and thus the whole-body content of these minerals.     

Feeding preterm infants after hospital discharge: effect of diet on body composition.

Our purpose in this study was to examine whole body composition, using dual energy x-ray absorptiometry (DEXA) during dietary intervention in preterm infants (< or = 1750 g birthweight, < or = 34 wk gestation). At discharge, infants were randomized to be fed either a preterm infant formula (discharge-6 mo; group A) or a term formula (discharge-6 mo; group B), or the preterm formula (discharge-term) and the term formula (term-6 mo; group C). Nutrient intake was measured between each clinic visit. To measure body composition, DEXA was used at discharge, term, 12 wk, 6 mo, and 12 mo corrected age. The data were analyzed by ANOVA. At discharge, no differences were noted in patient characteristics between groups A, B, and C. Although energy intakes were similar, protein and mineral intakes differed between groups (A > C > B; p < 0.0001). During the study, weight gain and LM gain were greater in group A than B. At 12 mo, weight, LM, FM, and BMM but not % FM or BMD were greater in group A than B. However, the effects of diet were confined to boys, with no lasting effects seen in girls. In summary, therefore, DEXA was precise enough to detect differences in whole body composition during dietary intervention. Increased weight gain primarily reflected an increase in LM and is consistent with the idea that the preterm formula more closely met protein and/or protein-energy needs in rapidly growing preterm male infants.     

Influence of protein and energy intakes on body composition of formula-fed preterm infants after term

The aim of the present study was to evaluate changes in body composition in 48 preterm infants in relation to protein and energy intakes from term up to 3 months of corrected age, using air displacement plethysmography. Protein intake (grams per kilogram per day) was negatively associated with percentage of fat mass at 1 month of corrected age. The high-protein-intake group showed greater gain in lean body mass gain than did the low-protein-intake group. This finding suggests that during the first month of corrected age, high protein intake results in a significantly different weight gain composition.     

Altered body composition in preterm infants at hospital discharge

Aim:  To test the hypotheses that body size is reduced and body composition altered in preterm infants at hospital discharge.
Methods:  Preterm infants (≤34 weeks gestation, ≤1750 g at birth) were enrolled. Body weight, length and head circumference were converted to standard deviation or z- scores. Body composition was measured using dual emission X-ray absorptiometry. The results were analysed using standard statistics.
Results:  One hundred and forty-nine infants (birth weight = 1406 ± 248 g, gestation = 31 ± 1.7 weeks) were studied. Postmenstrual age at discharge was 37 ± 1.2 weeks. Z -scores for head circumference, weight and length differed (−0.1 ± 0.6 > −1.4 ± 0.6 > −1.9 ± 0.6; p < 0.0001). Global fat-free mass was less in study infants than the reference infant at the same weight (2062 < 2252 g; p < 0.0001) or gestation (2062 < 2667 g; p < 0.0001). Global fat mass was greater in study infants than the reference infant at the same weight (307 > 198 g, 13 > 8%) or gestation (307 > 273 g; 13 > 9%; p < 0.0001). Changes in central fat mass closely paralleled those in global fat mass (r² = 0.76, p < 0.0001).
Conclusion:  Reduced linear growth and a reduced fat-free mass suggest that dietary protein needs were not met before discharge. A reduced fat-free mass coupled with an increased global and central fat mass echoes concerns about the development of insulin resistance and metabolic syndrome X in these high-risk infants.     

Growth and body composition in preterm infants with bronchopulmonary dysplasia

OBJECTIVE: To compare growth and body composition in preterm infants with bronchopulmonary dysplasia (BPD) with normal healthy term infants during the first year of life. DESIGN: Twenty nine preterm infants with BPD (mean (SD) gestational age 27.1 (1.6) weeks; birth weight 852 (173) g) were followed prospectively. Anthropometry and body composition determined by total body electrical conductivity were measured and compared with those of healthy term infants at the same post-term age. RESULTS: In infants with BPD, the mean weight standard deviation scores (SD scores) 6 weeks after term were significantly lower (-1.44 and -2.68, boys and girls respectively) than in healthy term infants of the same age and did not improve during the first year. The mean length SD score was significantly lower in infants with BPD 6 weeks after term than in healthy term infants of the same age, and, although it improved significantly during the first year, the mean length SD score in girls with BPD was significantly below 0 12 months after term. In infants with BPD, the mean free fat mass (FFM) SD score and the mean total body fat (TBF) SD score at 6 weeks post-term age were significantly below 0. The mean FFM SD scores (-1.01 and -2.56, boys and girls respectively) and the mean TBF SD scores (-1.14 and -2.40, boys and girls respectively) 12 months after term were significantly lower than in healthy term infants of the same age. CONCLUSIONS: Preterm infants with BPD have impaired growth, with a deficit in TBF and FFM already 6 weeks after term; FFM and TBF remain low compared with healthy term infants during the first year of life. Nutritional intervention studies in infants with BPD are needed to evaluate if nutrition is the major determinant of growth and body composition or if this pattern of growth in preterm infants with BPD is the result of disturbed endocrine control.     

Factors affecting body composition in preterm infants: Assessment techniques and nutritional interventions

Limited research has been conducted that elucidates the growth and body composition of preterm infants. It is known that these infants do not necessarily achieve extra-utero growth rates and body composition similar to those of their term counterparts. Preterm infants, who have difficulty in achieving these growth rates, could suffer from growth failure. These infants display an increased intra-abdominal adiposity and abnormal body composition when they achieve catch-up growth. These factors affect the quality of weight gain, as these infants are not only shorter and lighter than term infants, they also have more fat mass (FM) and less fat-free mass (FFM), resulting in a higher total fat percentage. This could cause metabolic syndrome and cardiovascular problems to develop later in a preterm infant's life. The methods used to determine body composition in preterm infants should be simple, quick, non-invasive and inexpensive. Available literature was reviewed and the Dauncey anthropometric model, which includes skinfold thickness at two primary sites and nine body dimensions, is considered in this review the best method to accurately determine body composition in preterm infants, especially in resource-poor countries. It is imperative to accurately assess the quality of growth and body composition of this fragile population in order to determine whether currently prescribed nutritional interventions are beneficial to the overall nutritional status and quality of life—in the short- and long-term—of the preterm infant, and to enable timely implementation of appropriate interventions, if required.     

Protein quality and quantity in preterm infants receiving the same energy intake

Fifteen low-birth-weight appropriate for gestational age infants, weighing 1.3 to 1.6 kg, were assigned to three isocaloric formulas differing in the quantity and form of nitrogen delivered. A balance study was done between 21 and 30 days after birth. Nitrogen retention expressed as milligram per kilogram per 100 kcal of metabolizable energy was greater with the 60:40 whey/casein and with the casein hydrolysate preparations than with the 20:80 whey/casein formula, which provided the same amount of energy (150 kcal/kg/day) but smaller quantities of protein (3.5 g/kg/day) than the two others (4.3 g/kg/day and 4.4 g/kg/day). Weight gain until discharge from the hospital and increment of height and head circumference over a three-month period showed an advantage of the two formulas providing higher intakes of protein. This study suggests that with high-energy intakes, protein quality does not affect nitrogen retention and growth unless the quantity of protein ingested falls below a critical level.     

Effects of recombinant human growth hormone treatment in intrauterine growth-retarded preterm newborn infants on growth, body composition and energy expenditure

The effects of recombinant human growth hormone treatment during the early postnatal period on growth, body composition and energy expenditure were studied in seven intrauterine growth-retarded newborns. Seven infants were studied as controls. No differences were seen in bodyweight or height gain (15.9 ± 1.5g/kg per day and 1.02 ± 0.24cm/week in the treated and 16.3 ± 1.4g/kg per day and 1.11 ± 0.30 cm/week in the control group). Skinfold growth rate was 0.52 ± 0.20 mm/week in the treated vs. 0.56 ± 0.28 mm/week in the control group. Total body water (as a percentage of body-weight, 80 ± 3.0% vs. 80 ± 4.0%) and energy expenditure (67.5 ± 7.4 vs. 66.7 ± 6.4kcal/kg per day) using ²H₂¹⁸O showed identical results in both groups. We conclude that recombinant human growth hormone treatment directly after birth in intrauterine growth-retarded newborn infants results neither in an increase in growth rate nor a change in body composition or energy expenditure during the early postnatal period.     

Evaluation of air-displacement plethysmography for body composition assessment in preterm infants

Background:Adiposity may contribute to the future risk of disease. The aim of this study was to evaluate the accuracy and reliability of an air-displacement plethysmography (ADP) system to estimate percentage fat mass (%FM) in preterm infants and to evaluate interdevice reliability in infants.Methods:A total of 70 preterm and 9 full-term infants were assessed. The accuracy of ADP measurements was assessed by determining reference %FM values using H(2)(18)O dilution measurement.Results:Mean %FM by ADP was 5.67 ± 1.84 and mean %FM by H(2)(18)O dilution was 5.99 ± 2.56. Regression analysis showed that %FM by ADP was associated with %FM by H(2)(18)O dilution (R(2) = 0.63, SE of estimate (SEE) = 1.65, P = 0.006). Bland-Altman analysis showed no bias (r = -0.48, P = 0.16) and 95% limits of agreement were -3.40 to 2.76 %FM. There was no difference in mean interdevice reliability %FM values (8.97 vs. 8.55 %FM) between ADP 1 and 2. Regression analysis indicated a low SEE (1.14% FM) and high R(2) (0.91); 95% limits of agreement were -1.87 to 2.71 %FM. The regression line did not differ significantly from the line of identity.Conclusion:ADP is a noninvasive, reliable, and accurate technique to measure preterm infants' body composition in both research and clinical settings.     

液体摄入量对早产儿死亡率与并发症发生率的影响

目的系统评价早产儿及低出生体重儿应用不同补液量的疗效及安全性,为临床早产儿合理补液提供依据。方法以生后早期补液量为干预措施,早产儿／低出生体重儿为纳入对象,按Cochrane系统评价方法,评价纳入研究的方法学质量并提取有效数据进行Meta分析。结果共纳入3个随机对照研究,纳入总病例数438例。生后1周时补液量〉150ml／（kg·d）的亚组患儿,动脉导管重新开放率、新生儿坏死性小肠炎发病率显著高于对照组（OR：2．86,95％CI：1．25～6．51;OR：8．32,95％CI：1．56～44．52）,与生后1周时补液量在130～150ml／（kg·d）的亚组分析结果显示差异无统计学意义。高补液量组最大体重下降百分比显著低于对照组（WMD=-2．54,95％CI：-3．95—-1．19）;两组死亡率、支气管肺发育不良发病率、颅内出血发病率差异无统计学意义。结论过高补液总量摄入1〉150ml／（kg·d）]给临床转归带来不利影响,而生后1周时130～150ml／（kg·d）的补液量是安全的。     

Energy intake, metabolic balance and growth in preterm infants fed formulas with different nonprotein energy supplements

OBJECTIVE: To study metabolic and energy balances, growth and composition of increased body mass in healthy preterm infants fed control formula or control formula with three different nonprotein energy supplements. PATIENTS AND METHODS: Growing preterm infants (birth weight < 1,500 g and gestational age < 31 weeks) were fed standard preterm formula (control group) or the same formula enriched with three different nonprotein energy supplements. An energy supplement of 23 kcal/kg/day was achieved by adding medium-chain triglyceride and dextrinomaltose in three different caloric ratios: 33:66 in group A, 66:33 in group B, and 85:15 in group C. Energy balance was determined by open-circuit continuous (5-6 hours) measurements of energy expenditure, with simultaneous measurement of 24-hour urinary nitrogen excretion. Metabolic balance was determined by measurements of energy intake, energy oxidation, and energy output in urine and stool. The composition of body mass accretion was determined as the accretion of fat and protein in the total weight gain. RESULTS: The fat accretion (4.9, 5.9, 6.2, and 3.8 g/kg/day in groups A, B, C and D, respectively) correlated directly with fat intake. Infants receiving standard energy intake had a fat percentage of weight gain significantly lower (28%) than that of the high-energy intake groups (31%, 40%, and 38% in groups A, B, and C, respectively). This difference corresponded to the results obtained from skinfold thickness measurements. CONCLUSIONS: Excess nonprotein energy is stored as fat regardless of its source (fat or carbohydrate). High caloric and medium-chain triglyceride intake in otherwise healthy growing preterm infants does not promote nitrogen retention.     

Nutritional assessment in preterm infants with special reference to body composition

In recent years, improvements in care have significantly improved survival in preterm and, particularily, the very low birth weight infant (VLBW). While immediate survival can be directly related to pulmonary maturity, several studies stress the importance of timely and adequate nutrition in these high-risk infants on a short- and long-term [1]. Yet, nutritional support remains a very controversial issue in these high-risk infants. Early provision of adequate intakes may be limited by clinical instability and immaturity. At the same time, nutritional requirements and methods of nutritional assessment are not well defined. The aim of this paper is to outline some of the methods used during nutritional assessment in preterm infants with special reference to the measurement of body composition.     

The effects of two extremes of dietary intake on protein accretion in preterm infants

A comparison has been made of protein accretion and growth in premature infants fed banked drip breast milk (BBM) or a preterm formula (PF). Protein accretion was calculated from the difference between dietary nitrogen intake and output in urine and stools, measured in a nutrient balance study. As expected, only the infants fed PF achieved the intrauterine growth rate. However, whilst weight gain in infants fed BBM was 71% of that in the group fed PF, the rate of protein deposition was less than 50%. As a result, the protein concentration in new tissue of infants fed BBM averaged 32% less than in those fed PF and 21% less than the lower end of the range reported to occur in utero. We speculate that infants fed BBM have an abnormally low protein concentration in their lean body mass.