Protein and Energy Intake during Weaning: I. Effects on Growth

ABSTRACT. The growth and food consumption of 30 healthy infants from 4 to 6 months of age have been measured. Two groups were assigned randomly to either a formula with 1.9 g of protein and 72 kcal per 100 ml (F₁) or 2.7 g of protein and 69 kcal per 100 ml (F₂). A third group of infants were fed breast milk (0.96 g of protein and 65 kcal per 100 ml (HM). All infants received supplementary food according to the same regimen and were fed ad libitum. The mean protein intake was 1.3, 2.6 and 3.6 g/kg/day in the HM-, F₁- and F₂-groups respectively. The corresponding mean energy intake was 80, 101 and 94 kcal/kg/day. The formula-fed infants had significantly higher protein and energy intakes when compared to the breast-fed group. No significant differences were found in the rate of growth of crown-heel length, head circumference or in weight gain. The differences in protein intake between the breast- and formula-fed infants without differences in growth indicate that the formulas may provide a protein intake in excess to the needs.     

Evidence for Amino Acid Induced Cholestasis in Very-low-birth-weight Infants with Increasing Enteral Protein Intake

ABSTRACT. In the present investigation 32 very-low-birth-weight (VLBW) infants fed at three different levels of protein intake (2.92 g/kg/d from human milk, 3.22 and 4.06 g/kg/d from formula) were studied at the mean age of 21 days. Serum total α-amino nitrogen concentration correlated directly to total bile acid concentration. The serum and urine a-amino nitrogen and the serum bile acid concentration correlated with protein intake. The increase in protein intake was accompanied by a concomitant decrease in the intraluminal bile acid concentration in the AGA infants. The results offer indirect evidence of decreased bile flow in YLBW-infants on excessive oral protein intake. The cholestatic effect could be mediated by an increase in the plasma amino acid concentration.     

Amino Acid Levels in the Critically ill Preterm Infant Given Mother's Milk Fortified with Protein from Human or Cow's Milk

ABSTRACT. Twenty preterm infants undergoing neonatal intensive care were randomly allocated to one of two feeding regimens: human milk enriched with either human milk protein (HMP) or adapted cow's milk protein (CMP). The birthweights (1076 ± 301 g; 1031 ± 309 g) and the gestational ages (28.4 ± 1.6 weeks; 27.7 ± 2.1 weeks) were comparable. The amount of protein added to the milk was set at 0.7 g/100 ml in order to provide a total supply of 3.0-3.5 g/kg/24 h. All infants received additional amounts of carbohydrate, calcium, phosphorous, and sodium chloride. Capillary whole blood amino acids were measured with high pressure liquid chromatography (HPLC). The amino acid levels did not differ significantly when the feeding groups were compared week by week, but the glycine/valine ratio was higher (p<0.05) in the HMP group after three weeks of fortification. Longitudinal changes after protein enrichment could be demonstrated in both groups. Alanine and threonine increased after one week (p<0.01) in both groups. Glycine in the HMP group peaked after two weeks (p<0.02), and valine in the CMP group increased (p<0.02) after one week on the feeding regimen. However, the amino acids never reached levels above those seen after a meal in normal term newborns. Other variables related to protein intake, such as protein and urea in serum, did not vary between the groups. Growth, expressed as gains in weight, length, and head circumference was poor but comparable. The quality of the protein, whether a human milk protein isolate or a cow's milk whey protein product, used for the fortification of human milk up to a protein load of 3.0-3.5 g/kg/24 h, did not cause any alterations of significance in the amino acid profiles of peripheral blood.     

Infant Self-Regulation of Breast Milk Intake

ABSTRACT. In an experimental study to determine whether augmentation of maternal milk supply affects infant intake, 18 mothers of exclusively breast-fed infants stimulated milk supply by daily expression of extra milk for 2 weeks. Infant milk intake was recorded before, during and after this expression phase. All but 4 mothers increased milk production by >73 g/day over baseline, with an average increase of 124 g/day. On the average, the 14 infants of mothers who increased milk production took in significantly more milk immediately following the expression phase (849 vs. 732 g/day), but about half of them returned to near baseline levels of milk intake after 1-2 weeks. Net change in infant intake at the end of the study was positively correlated with infant weight-for-length ( r =0.59) and age ( r =0.58), and was unrelated to baseline milk intake ( r =-0.06). Therefore, the wide range in breast milk volume in well-nourished populations is due more to variation in infant "demand" than to inadequacy of milk production.     

Human Milk Lacto-Engineering: Growth Nitrogen Metabolism,and Energy Balance in Preterm Infants

ABSTRACT. Fourteen 3-day metabolic balance studies were carried out in 8 healthy male preterm infants (birthweight 1270±170 g, gestational age 30±2 weeks) fed 183±7 ml/kg/day of a human milk formula made of incompletely skimmed human milk enriched with lyophilized whole human milk, minerals, medium chain triglycerides and linoleate. Daily intakes per kilo bodyweight were for protein 3.5±0.3 g, fat 7.0±2.1 g, and energy 573±88 kj (137 kcal). Weight gain was 29±5 g per day and nitrogen retention was 317±52 mg/kg/day. Fat absorption was 76± 12 %. Renal acid and solute loads were low and there was no metabolic acidosis, hyperazotemia or hyperaminoacidemia, except for tyrosine. It is concluded that preterm infants fed a human milk formula have similar growth rates and nitrogen retentions as foetuses in utero or preterm infants fed their own mother's milk.     

Human Milk Lacto-Engineering: Growth Nitrogen Metabolism, and Energy Balance in Preterm Infants

ABSTRACT. Fourteen 3-day metabolic balance studies were carried out in 8 healthy male preterm infants (birthweight 1270±170 g, gestational age 30±2 weeks) fed 183±7 ml/kg/day of a human milk formula made of incompletely skimmed human milk enriched with lyophilized whole human milk, minerals, medium chain triglycerides and linoleate. Daily intakes per kilo bodyweight were for protein 3.5±0.3 g, fat 7.0±2.1 g, and energy 573±88 kj (137 kcal). Weight gain was 29±5 g per day and nitrogen retention was 317±52 mg/kg/day. Fat absorption was 76± 12 %. Renal acid and solute loads were low and there was no metabolic acidosis, hyperazotemia or hyperaminoacidemia, except for tyrosine. It is concluded that preterm infants fed a human milk formula have similar growth rates and nitrogen retentions as foetuses in utero or preterm infants fed their own mother's milk.     

Epidermal Growth Factor in Cow's Milk and Milk Formulas

ABSTRACT. Epidermal growth factor (EGF) in human milk, cow's milk and 10 different milk formulas was measured by radioreceptor assay (RRA) using human placental membrane as an EGF receptor. The raw and pasteurized cow's milk contained 324.2 ng/ml and 155.0 ng/ml of RRA-EGF, respectively. These values were almost the same as that found in human milk, when the concentration was expressed as the proportion of protein contents in the samples. On the other hand, no trace of RRA-EGF was detected in 9 different milk formulas, and only one contained a very small amount of it.     

Urinary and Serum Urea as Indicators of Protein Metabolism in Very Low Birthweight Infants Fed Varying Human Milk Protein Intakes

ABSTRACT. Urea concentrations in serum and urine were measured in 28 growing, very low birth weight, appropriate-for-gestational age infants fed varying human milk protein intakes (range 1.7 to 3.9 g/kg/day). We found a high correlation between serum urea values at the end of the study and mean protein intake ( r ₃=0.85, p <0.001) and between urinary urea concentrations in eight-hour urine collections and protein intake ( r ₃=0.81, p <0.001). All serum and urine urea values were below 1.6 and 18 mmol/l, respectively, at protein intakes less than 3 g/kg/day. Higher protein intakes caused higher serum and urinary urea concentrations. We also found a strong correlation between the individual serum and urinary urea values at the end of the study ( r ₃=0.90, p <0.001). The presented data are consistent with the growth data previously reported and indicate that inadequate or excessive protein intakes can be detected by measurement of urea concentrations in serum and/or urine. If urine urea samples alone can be used for estimating optimal protein intake, painful blood sampling procedures could be obviated.     

Development of a Human Milk Protein Standard

ABSTRACT. Accurate quantitation of the protein content of human milk (HM) is clinically important for both determining protein and energy intakes of HM-fed infants. Protein can be determined by Kjeldahl analysis or colorimetric assays. Colorimetric assays are rapid and convenient, but usually overestimate the protein content when compared to Kjeldahl protein (KP). In this study a protein standard based on human milk protein (HMPS) was isolated by size exclusion column chromatography. Purity and composition of the standard was determined by gel electrophoresis, Kjeldahl and amino acid analyses. The protein content of 20 mature milk samples was determined by the Lowry, BCA and BioRad colorimetric assays, using bovine serum albumin, human serum albumin/IgG, and HMPS as standards. These results were compared with KP results using Student's f-test. All colorimetric assays overestimated milk protein content; however, the Lowry assay gave the lowest protein levels, with our protein standard yielding values closest to the KP value.     

Type of Milk Feeding and Nutrient Intake during Infancy The Leiden Pre-School Children Study

ABSTRACT. During infancy different types of milk feeding can be used, i.e. breast milk, formula or cow's milk. In the Leiden Pre-School Children Study food intake and anthropometric data of four-, six- and nine-month-old infants were collected to study the influence of the type of milk feeding on the energy and nutrient intake on one hand and on height and weight on the other hand. All three different types of milk feeding were studied in the four-month-old infants. In the six- and nine-month-old infants food intake data of those breast-fed were not collected. No differences in energy intake and in height and weight were found between formula-fed infants and infants fed on cow's milk at the three age-levels. The influence on nutrient intake, on the contrary, was substantial. Compared to formula feeding, cow's milk feeding resulted in a significantly higher intake of protein, sodium, potassium, calcium and phosphorus and a significantly lower intake of linoleic acid, iron and ascorbic acid. Cow's milk feeding at four months was more prevalent among less educated mothers than among mothers with higher education. Breast feeding was strongly positively related to educational level of the mother at all three ages. It can be concluded that more information should be given about the advantages and disadvantages of different types of milk feeding especially to less educated mothers.     

Growth and Plasma Amino Acid Concentrations in Very Low Birthweight Infants Fed Either Human Milk Protein Fortified Human Milk or a Whey-Predominant Formula

ABSTRACT. 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.     

The Effect of Intrauterine Malnutrition on the Term Infant

The developmental outcome of 33 newborn infants with clinical intrauterine malnutrition at birth and 13 clinically well nourished infants from a middle to high socio-economic population have been followed from birth to 12–14 years of age. Psychometric studies revealed a lowering of the IQ score in malnourished infants compared to well nourished infants (104 ± 15 compared to 121 ± 13, p < 0.05) and a need for special education ( p < 0.03). Forty-five percent of the malnourished infants'birth weights were above the 10th percentile on the Colorado Intrauterine Growth Grid. The Full Scale IQ of malnourished infants with BW greater and less than 10th percentile on the Colorado Intrauterine Growth Grid were comparable. Malnourished infants with birth weights > 10th percentile had lower IQ scores than well nourished infants (101 ± 13 compared to 121 ± 13, p < 0.006). Thirty-nine percent of the infants with handicaps would have been missed if only infants with birth weights < 10th percentile were considered high risk.     

Heparin Cofactor II, Antithrombin and Protein C in Plasma from Term and Preterm Infants

ABSTRACT. The coagulation inhibitors heparin cofactor II (HCII), antithrombin (AT) and protein C (PC) were measured in healthy term and preterm infants in order to establish reference standards. The mean value for HCII in term infants was found to be about half of the adult values. Values below 25% in healthy infants may suggest hereditary deficiency states. One girl with congenital HC II deficiency was detected. Mean AT and PC levels were somewhat higher than HC II. Healthy preterm infants have significantly lower HC II and AT values than healthy term infants. Serial AT measurements have been used in monitoring seriously ill infants and used as a prognostic indicator. In a small number of unhealthy neonates HC II was reduced to an even greater extent than AT, and on recovery normalized more rapidly than AT.     

Copper Deficiency in a Japanese Infant on Milk Formula

Copper deficiency in human is uncommon. We described a 7-month-old Japanese infant who developed copper deficiency while being fed milk formula alone, and exhibited neutropenia, sideroblastic anemia and bone changes resembling scurvy and osteoporosis. We treated her with oral copper solution. Within 7 days of treatment, neutrophils and reticulocyte counts remarkably increased. Anemia was corrected by 2 weeks after initiation of copper therapy. Bone radiography showed remarkable improvement, and the maturation arrest and cytoplasmic vacuoles in the early myeloid and erythroid series on the bone marrow examination had disappeared after copper therapy. The plasma and erythrocyte copper concentrations, and serum ceruloplasmin levels returned rapidly to normal range. The patient has been doing well after discontinuing copper supplements. Although there has been no report of copper deficiency in Japanese infants nourished with milk formula alone, marginal copper deficiency, which escapes clinical recognition and is spontaneously cured when solid foods are added, may not be so uncommon in Japan. The recommended daily intake of copper cannot be achieved, if a Japanese infant, especially a premature baby, is nourished with milk formula alone. Therefore, Japanese milk formula must be !supplemented with copper.     

Zinc and Copper Concentrations in Human Milk and Infant Formulas

Objective

Available accurate data on the concentrations of copper (Cu) and zinc (Zn) in human milk throughout lactation and infant formulas is important both for formulating nutritional requirements for substances and to provide a base line for the understanding the physiology of their secretion. The objective of this study was to analyze the concentrations of zinc and copper in infant formulas and human milk during prolonged lactation. Levels of these metals were examined in relation to selected parameters such as age, weight, height, education and occupation of mothers.

Methods

Thirty mothers referred to the selected clinics in Tehran entered the study. Human milk samples were collected at 2 months postpartum. Zinc and copper concentrations were determined by atomic absorption spectrophotometer.

Findings

The mean values of Zn and Cu in human milk were 2.95±0.77mg/L and 0.36±0.11 mg/L. The mean values of Zn and Cu in infant formulas were 3.98±0.25 mg/L and 0.53±0.17mg/L.

Conclusion

No significant relationship was found between levels of trace elements in human milk and evaluated parameters such as age, weight, height, education and occupation of mothers. The concentrations of zinc and copper in breast milk were lower than those reported in the literature.     

Choice of formula and human milk supplement for preterm infants in Australia

Human milk (HM) is considered to be the optimal feed of choice for neonates, however, for preterm infants, HM fortifiers are often added to increase growth. If HM is unavailable, preterm formula is the next best option for preterm infants. Choosing which fortifier, if any, to use or which formula can be confusing. In this paper, the composition of milk feeds available in Australia and New Zealand is reviewed with the aim of assisting paediatricians to decide which feed is most appropriate for their patients.     

Cellular Composition Including Lymphocyte Subsets in Preterm and Full Term Human Colostrum and Milk

ABSTRACT. The cellular composition of colostrum (within 72 hours post partum) and mature milk samples (5th–7th day post partum) from 20 mothers delivering preterm babies and 20 mothers delivering full term babies was examined. Lymphocyte subsets including T cells, B cells, T⁴ and T⁸ cells were quantitated by indirect immunoperoxidase staining using specific monoclonal antibodies. The mean total cell count in preterm colostrum (9 338/mm³) was significantly higher than in full term colostrum (5 594/mm³). Similarly, counts for macrophages, neutrophils and lymphocytes were significantly higher in preterm colostrum and milk as compared to full term colostrum and milk. B and T lymphocytes including T⁴ and T⁸ cells were identified in both preterm and full term breast milk. The absolute count of T, B, T⁴ and T⁸ cells was significantly higher in preterm colostrum compared to term colostrum, though the relative percentage distribution of lymphocyte subsets showed no significant difference between the two groups. T and B cells constituted about 74% and 26% of total lymphocytes, respectively in preterm as well as full term colostrum and about 69% and 31% in preterm and full term milk. The mean T⁴/T⁸ ratio was higher in preterm colostrum than term colostrum, being 1.82 and 1.60 respectively. However, this difference was not significant statistically and did not change statistically in the milk sample.     

Influence of Different Protein Intake on Renal Growth in Young Rats

ABSTRACT. We have examined the effect of high protein intake on kidney growth and function in growing rats. The rats were kept on an isocaloric diet containing 12%, 21% and 50% protein, from weaning (16 days) until the time of investigation (18, 20, 24,40 or 80 days). There was no significant difference between the 12% and 21% protein groups in any of the parameters studied. 50% protein increased body weight (BW) and kidney weight (KW). The increase in kidney weight was already evident after 2 days and exeeded the increase in body weight in all age groups. At 24 days renal cortical DNA and the protein/DNA ratio were significantly increased in the 50% protein group. At 40 days the cortical DNA content, but not the protein/DNA ratio, was significantly increased in the 50% group. The glomerular filtration rate (GFR) was studied at 40 days. Total GFR as well as GFR/BW was significantly higher in the 50% group than in the 21% group. In one protocol the diet was discontinued at age 40 days and the rats were studied at age 80 days. In these rats all parameters of renal size and function were the same as in the rats that had had a normal (21%) protein intake from weaning. We conclude that in young rats high protein intake reversibly increases GFR out of proportion to BW and selectively and reversibly stimulates kidney growth by stimulating cell proliferation.     

Food Intake and Growth of Infants between Six and Twenty-six Weeks of Age on Breast Milk, Cow's Milk Formula, or Soy Formula

ABSTRACT. In 59 normal infants attending well-baby clinics, food consumption was registered until 26 and growth until 52 weeks of age. They were either breast-fed or formula-fed with a cow's milk product or a soy protein product. The average consumption of breastmilk was 746, 796, 722 and 689 g/day at 6, 14, 22 and 26 weeks respectively. Bottle-fed infants received larger volumes, and at 6 and 14 weeks were the calculated total energy intakes significantly higher than in breast-fed infants. No differences were seen between the feeding groups with respect to length and the sum of four skin folds. The soy formula-fed children, who happened to be 200 g heavier at birth, had lower weight gains during the first 6 weeks than the other two groups. Thereafter, the average weights of the soy formula group did not differ from the other groups. At 3 months, the soy formula-fed children displayed a slower mineralisation and maturation of bone, but the difference was no longer significant when re-examined at 6 months. Formulas based on soy protein isolates seem to be acceptable as substitutes for cow's milk formulas in feeding normal infants.     

Bioavailability of Urea Nitrogen for the Low Birthweight Infant

ABSTRACT. Previous studies have demonstrated increased retention (40%) of dietary urea nitrogen by term infants recovering from infection compared to healthy infants (13%), possibly due to a higher requirement for nitrogen. Since low birthweight infants also have a high requirement for nitrogen, the bioavailability of urea nitrogen was investigated in low birthweight infants using ¹⁵N, ¹⁵N-urea. Four low birthweight infants (gestational age = 30 ±2.2 weeks [mean ± SD, birthweight = 1.4 ±0.3 kg) were fed formula enriched with ¹⁵N, ¹⁵N-urea. Metabolic balance studies (72 hours) were performed with urine and fecal collections. Nitrogen was quantitated by Kjeldahl analysis and ¹⁵N, ¹⁵N-urea by gas chromatography/mass spectrometry. Mean nitrogen intake was 489 ± 32 mg/kg/d, with 75 % nitrogen absorption and 62% nitrogen retention. Maximum urinary enrichment was 8%. Cumulative ¹⁵N, ¹⁵N-urea excretion was 72%, resulting in 28% retention. Thus the bioavailability of urea nitrogen for low birthweight infants appears to be intermediate between compromised and normal term infants.