Diet and faecal flora in the newborn: casein and whey proteins.

Despite the extensive modifications of cows'' milk to make an infant formula resemble human breast milk, we showed in a previous study that the faecal flora of breast fed babies still differs substantially from that of formula fed babies. This paper describes the effects that differences in the distribution of whey proteins and caseins exert on the faecal flora. Faecal flora was examined in 33 babies receiving a whey formula, 29 babies receiving a casein formula, and 38 breast fed babies. Subsequently fewer babies in each group were studied at weeks 7, 11, and 15. More whey fed babies were colonised with bifidobacteria at 14 days compared with the casein fed group, more casein fed babies were colonised with bacteroides (at 14 days), and more had a dominant growth of enterococci (at week 7). It seems therefore that during the first two months that the whey predominant formula induced a faecal flora generally closer to that of breast fed babies than did a casein formula.     

Diet and faecal flora in the newborn: lactoferrin.

The faecal flora of breast fed babies differs from that of bottle fed babies. We have shown that the use of a whey predominant formula rather than a casein predominant one induced a faecal flora generally closer to that of breast fed babies but substantial differences remained. The whey proteins of breast milk include much more lactoferrin than is found in cows'' milk. Observations both in animals and in vitro suggest that lactoferrin could be responsible for some of these differences between bottle and breast fed babies. This study was designed to determine the effects on faecal flora of the addition of bovine lactoferrin to the diet of bottle fed babies while holding other qualities of their diet constant. As lactoferrin is an iron binding protein three test formulas were used: (a) no added iron and no added lactoferrin (basic), (b) no iron but added lactoferrin (L), and (c) added iron and lactoferrin (LF). The addition of lactoferrin had little effect upon the faecal microflora and did not move the pattern of the faecal flora in the direction of the breast fed baby. The addition of iron to the formula had more effect on the faecal flora than did lactoferrin. At day 4 it encouraged Escherichia coli and discouraged staphylococcal faecal colonisation. At day 14 the addition of iron to the formula discouraged bifidobacteria. The reasons why bovine lactoferrin was ineffective in vivo in this study are discussed.     

Diet and faecal flora in the newborn: iron.

The faecal flora of a baby receiving a modern infant formula is substantially different from that of a breast fed baby. This difference is a little less when whey based formulas are used. The addition of bovine lactoferrin has no effect and there is some evidence that the presence of added iron in a formula moved the faecal flora further away from that of a breast fed baby. the iron content of currently used infant formulas is much higher than that of breast milk. The effect of the addition of iron to both whey and casein based formulas on the faecal flora was examined in further detail. Faecal flora were examined at 14 days of age in 33 babies receiving a whey formula fortified with iron, 29 babies receiving a whey formula without iron, 29 babies receiving a casein formula fortified with iron, and 24 babies receiving casein formula without iron. Subsequently fewer babies in each group were examined at week 7, 11, and 15. The addition of iron to both casein and whey formulas discouraged colonisation and growth of staphylococci and bacteroids but encouraged the colonisation and growth of clostridia and enterococci. The type of protein and not the iron content had more effect upon the growth of bifidobacteria; both whey formulas, fortified or not, encouraged the colonisation by bifidobacteria. If an infant formula, for use in the first few months, is to mimic the physiological effects of breast milk, there may be microbiological arguments for not fortifying it with iron. However, large empirical trials would be necessary before advocating such a policy.     

Experimental milk formulae with reduced protein content and desialylated milk proteins: influence on the faecal flora and the growth of term newborn infants

We have assessed the growth, tolerance and the faecal flora composition in healthy infants on different feeding regimens. Four groups of infants were fed exclusively on mother's milk, a standard formula and two experimental formulae. The first experimental formula consisted of a milk with a reduced protein content (1.2 g/100 ml), the second in a formula with the same protein content and with milk proteins desialylated by mild acid hydrolysis. The aim of the study was to test whether lowering the protein content and/or modifying the proteins by desialylation would favour the development of a bifidus flora. A bifidus flora was detected in 60% of breastfed infants at 1 month of life. All formulae employed during the study failed to induce a prevalence of colonization with bifidobacteria at 1 month of age. The two experimental milk formulae were well tolerated, but the infant growth rate was slightly lower as compared to the breastfed infants and the infants fed the standard formula. The presence in milk formulae of pre-digested and desialylated proteins can offer some advantages in term of digestibility and mimic a physiological intestinal mechanism of the infant.     

Diet and faecal flora in the newborn: breast milk and infant formula.

This study examined the faecal flora on days 4, 14, and 28 of 17 breast fed babies and 26 bottle fed babies receiving a modern infant formula based on demineralized whey. Generally among breast fed babies bifidobacteria and staphylococci were the predominant organisms, whereas in the formula fed babies the predominant organisms were enterococci, coliforms, and clostridia. Despite the extensive modification of cows'' milk to make an infant formula resemble human breast milk, the results are very similar to those previously reported with unmodified cows'' milk baby feeds. The exact dietary factor responsible for these microbiological differences is unclear and in succeeding papers we have looked at the effects of protein quality, in particular the content of whey proteins, casein, and lactoferrin.     

Diet and faecal flora in the newborn: nucleotides.

Breast milk contains nucleotide salts that are only present in minimal amounts in modern infant formulas prepared from cows' milk. Nucleotides have been suggested as cofactors for the growth of bifidobacteria in vitro. Bifidobacteria are found to be more numerous in the faeces of breast fed babies compared with those of formula fed babies. Faecal flora were examined at 2 weeks of age in 32 babies who from birth had been fed a whey based formula supplemented with nucleotide monophosphate salts, 33 babies fed an unsupplemented formula, and 21 breast fed babies. Faecal flora were also examined at 4 weeks, and 7 weeks but with fewer babies in each group. Most differences were found at 2 weeks of age when more babies fed the nucleotide supplemented formula were colonised with Escherichia coli and more had E coli as the dominant organism in their faecal flora. Fewer of these babies were colonised with bifidobacteria. The counts of bifidobacteria and enterococci were reduced in the nucleotide supplemented group but bacteroides accounted for a higher percentage of the total flora in this group of babies. Supplementation of a formula with nucleotide salts did not make the faecal flora closer to that of breast fed infants as the growth of bifidobacteria was discouraged. While there may be arguments to support the addition of nucleotides to infant formula the results of this study do not support their addition for the enhancement of bifidobacteria in the faecal flora.     

Cow milk-specific humoral and cellular immune response in infants with high risk of atopy under feeding a whey hydrolysate infant formula

BACKGROUND: Hypoallergenic infant formulas (HAF) were developed for atopy prevention in infants with high risk of atopy if these cannot be breastfed. HAF mount an antigen-specific immune response in infants. The aim of the study was to analyse the immune response in infants fed with a new infant formula based on a whey hydrolysate (HAF) and to compare it with that of exclusively breastfed controls. PATIENTS AND METHODS: Plasma concentrations of cow milk-specific IgE were analysed in 94 infants with high risk of atopy, 44 were exclusively breastfed, 50 were fed with HAF. In addition, cow milk-specific IgG antibodies (26 breastfed, 30 fed with HAF) as well as proliferation of periph-eral blood mononuclear cells to bovine beta-lactoglobulin (BLG) (41 breastfed, 47 fed with HAF) were tested. Specific IgE and IgG antibodies were determined using enzymoimmunometric assay (Alastat). Cellular proliferation was measured using tritiated thymidine incorporation assay after 6 day stimulation with BLG. RESULTS: Elevated IgE to cow milk antibodies (> 0.35 kU/L) were detected in two infants from the breastfed group and in one from the HAF-fed group. The plasma concentrations of milk specific IgG antibodies in HAF-fed infants were insignificantly higher than those in breastfed ones. No significant difference was found in bovine BLG-specific cell proliferation between both groups. CONCLUSION: Concerning the properties investigated like antigenicity, allergenicity and immunogenicity, the extensively hydrolysed whey based hypoallergenic formula does not significantly differ from mother milk in 6 month-old infants with an increased atopy risk.     

Comparison of a partially hydrolyzed infant formula with two extensively hydrolyzed formulas for allergy prevention:A prospective, randomized study

The aim of this study was to compare the allergy‐preventive effect of a partially hydrolyzed formula with two extensively hydrolyzed formulas, in infants with a high risk for development of allergic disease. High‐risk infants from four Danish centres were included in the period from June 1994 to July 1995. Five‐hundred and ninety‐five high‐risk infants were identified. High‐risk infants were defined as having bi‐parental atopy, or a single atopic first‐degree relative combined with cord blood immunoglobulin E (IgE) ≥ 0.3 kU/l. At birth all infants were randomized to one of three different blinded formulas. All mothers had unrestricted diets during pregnancy and lactation and were encouraged to breast‐feed exclusively. If breast‐feeding was insufficient, one of the three formulas, according to randomization, was given during the first 4 months. It was recommended not to introduce cow's milk, cow's milk products, and solid foods until the age of 4 months. After the age of 4 months a normal unrestricted diet and conventional cow's milk‐based formula were given when needed. All infants were followed‐up prospectively with interview and physical examination at the age of 6, 12, and 18 months, and if any possible atopic symptoms were reported. If food allergy was suspected, controlled elimination/challenge procedures were performed in a hospital setting. Of 550 infants included in the study, 514 were seen at all visits and 36 were excluded owing to non‐compliance. Of 478 infants who completed the study, 232 were exclusively breast‐fed, 79 received an extensively hydrolyzed casein formula (Nutramigen), 82 an extensively hydrolyzed whey formula (Profylac), and 85 a partially hydrolyzed whey formula (Nan HA), during the first 4 months of life. These four groups were identical in regard to atopic predisposition, cord blood IgE, birthplace, and gender. Exclusively breast‐fed children were exposed less to tobacco smoke and pets at home and belonged to higher social classes, whereas the three formula groups were identical concerning environmental factors. The frequency of breast‐feeding was high; only eight (2%) children were not breast‐fed at all. The three formula groups were identical in regard to duration of breast‐feeding and age at introduction of formula and solid foods. No significant differences were found in the three groups of infants receiving formula milk regarding the cumulative incidence of atopic dermatitis or respiratory symptoms. The cumulative incidence of parental‐reported cow's milk allergy was significantly higher in children fed partially hydrolyzed formula (Nan HA) compared with extensively hydrolyzed formula (Nutramigen or Profylac) at 12 and 18 months (NanHA, 7.1%; Nutramigen, 2.5%; Profylac, 0%; p = 0.033). The cumulative incidence of confirmed cow's milk allergy was 1.3% (three of 232) in exclusively breast‐fed infants, 0.6% (one of 161) in infants fed extensively hydrolyzed formula (Nutramigen or Profylac), and 4.7% (four of 85) in infants fed partially hydrolyzed formula (Nan HA). Partially hydrolyzed formula was found to be less effective than extensively hydrolyzed formula in preventing cow's milk allergy, 0.6% vs. 4.7% (p = 0.05), but because of the small number of cases the results should be interpreted with caution. Compared with other similar studies the frequency of atopic symptoms was low, even though the dietetic intervention did not include either maternal diet during lactation or dietary restrictions to the children after the age of 4 months.     

Supplementation of an adapted formula with bovine lactoferrin: 1. Effect on the infant faecal flora

The development of the infant faecal flora was studied over the first three months of life in infants receiving breast milk, a modern adapted formula and adaptations of this formula. Breast-fed infants developed a flora rich in Bifidobacterium sp. Facultative anaerobes were ubiquitous, but in relatively small numbers within the diet group. Other obligate anaerobes, such as Clostridium sp. and Bacteriodes sp. were rarely isolated. Standard formula produced a flora rich in bifidobacteria, but the growth of facultative organisms was not suppressed by this diet. Clostridium sp. and Bacteroides sp. were more common in this feeding group. After the addition of lactoferrin at 10 mg/100 ml to the formula diet, a flora similar to that of the standard formula-fed babies was achieved. Lactoferrin at 100 mg/100 ml was able to establish a "bifidus flora" in half of the babies given this formula, but only at age three months. Clostridium sp. and Bacteroides sp. were common faecal isolates from babies receiving both the lactoferrin diets.     

Preventive effect of feeding high-risk infants a casein hydrolysate formula or an ultrafiltrated whey hydrolysate formula. A prospective, randomized, comparative clinical study

In a prospective study of a 1-year birth cohort of 158 high-risk infants the effect of feeding breastmilk, a casein hydrolysate (Nutramigen®) or a new ultrafiltrated whey hydrolysate (Profylac®) on the development of cow milk protein allergy/intolerance (CMPA/CMPI) was assessed and compared. All the infants had biparental or severe single atopic predisposition, the latter combined with cord blood IgE ≥ 0. 5 kU/L. At birth all infants were randomized to Nutramigen or Profylac, which was used when breastfeeding was insufficient or not possible during the first 6 months of life. During the same period this regimen was combined with avoidance of solid foods and cow milk protein. All mothers had unrestricted diets and were encouraged to do breastfeeding only. Moreover, avoidance of daily exposure to tobacco smoking, furred pets and dust-collecting materials in the the bedroom was advised. The infants were followed prospectively from birth to 18 months of age. All possible atopic symptoms were registered and controlled elimination/challenge studies were performed when symptoms suggested CMPA/CMPI. A total of 154 (97%) were followed up and 141 followed the diet strictly. Eighty-eight (62%) of the infants were breastfed for at least 6 months, 20 (14%) were breastfed exclusively, 59 and 62 had varying amounts of Nutramigen or Profylac respectively. CMPA/CMPI was diagnosed in 1/20, 1/59 and 3/62 in the breastfed, the Nutramigen and Profylac groups respectively, but 1 of the latter also had Nutramigen. None of the infants showed reactions against Nutramigen or Profylac. In 4 infants symptoms were provoked by breastmilk when the mother ingested cow milk and in 1 only by cow milk. The incidence of CMPA/CMPI among the infants who followed the dietary prevention programme was 3. 6% (5/141) which was a significant reduction compared to 20% (15/75) in an identically defined high-risk group without dietary preventive measures. None of the infants in the prevention group developed CMPA/CMPI after the age of 6 months. We conclude that feeding breastmilk, an extensively hydrolysed casein formula (Nutramigen) or an ultrafiltrated whey hydrolysate (Profylac) combined with avoidance of solid foods during the first 6 months of life in high-risk infants significantly reduced the cumulative incidence of CMPA/CMPI during the first 18 months of life. No difference was noted whether the infants were fed breastmilk, Nutramigen or Profylac and a diet period of 6 months seems sufficient. Both formulae were well tolerated and accepted by the infants.     

The composition of the faecal microflora in breastfed and bottle fed infants from birth to eight weeks

Recent technical advances have improved the possibilities to classify anaerobic bacteria. The aim of the present study was to examine the validity of the time-honoured opinion that the faecal flora is dominated by bifidobacteria in breastfed infants but not in bottle fed ones. The composition of the faecal flora of 15 breastfed and of 7 bottle fed infants was followed from birth to 8 weeks. Strictly anaerobic conditions were carefully applied. At 5 days and 3 weeks the incidence of Staph. epidermidis was significantly greater in the breastfed group compared to the bottle fed one. We were unable to confirm earlier reports of difference in the anaerobic flora between breastfed and bottle fed infants. In both feeding groups Bacteroides dominated among the anaerobic bacteria and bifidobacteria occurred in less than half of the faecal specimens. The results of the study add to other recent observations that it has been increasingly difficult to demonstrate bifidobacteria in babies delivered in large, urban hospitals. We found different frequencies of bifidobacteria in infants from different wards, suggesting the importance of environmental factors in gut colonization after delivery.     

The Composition of the Faecal Microflora in Breastfed and Bottle Fed Infants from Birth to Eight Weeks

ABSTRACT. Recent technical advances have improved the possibilities to classify anaerobic bacteria. The aim of the present study was to examine the validity of the time-honoured opinion that the faecal flora is dominated by bifidobacteria in breastfed infants but not in bottle fed ones. The compositon of the faecal flora of 15 breastfed and of 7 bottle fed infants was followed from birth to 8 weeks. Strictly anaerobic conditions were carefully applied. At 5 days and 3 weeks the incidence of Staph, epidermidis was significantly greater in the breastfed group compared to the bottle fed one. We were unable to confirm earlier reports of difference in the anaerobic flora between breastfed and bottle fed infants. In both feeding groups Bacteroides dominated among the anaerobic bacteria and bifidobacteria occurred in less than half of the faecal specimens. The results of the study add to other recent observations that it has been increasingly difficult to demonstrate bifidobacteria in babies delivered in large, urban hospitals. We found different frequencies of bifidobacteria in infants from different wards, suggesting the importance of environmental factors in gut colonization after delivery.     

Spoonfeeding is associated with increased infant weight but only amongst formula‐fed infants

Infant feeding experiences are important for the development of healthy weight gain trajectories. Evidence surrounding milk feeding and timing of introduction to solids is extensive; however, the impact of the method of introducing solids on infant growth has been relatively underexplored. Baby‐led weaning (where infants self‐feed family foods) is proposed to improve appetite regulation, leading to healthier weight gain and a reduced risk of obesity. However, the evidence is mixed and has methodological inconsistencies. Furthermore, despite milk being a large part of the infant diet during the period infants are introduced to solid foods, its influence and interaction with introductory style have not been considered. The aim of this study was to explore growth among infants aged 3–12 months according to both style of introduction to solid foods and milk feeding; 269 infants were weighed and measured, and body mass index (BMI) computed. The results showed that overall, infants who were spoon‐fed (compared with self‐fed) at introduction to complementary feeding (CF) had greater length (but not weight or BMI). However, when milk feeding was accounted for, we found that infants who were both spoon‐fed and fully formula fed had greater weight compared with spoon‐fed, breastfed infants. There was no significant difference in weight among self‐fed infants who were breastfed or formula fed. The results highlight the importance of considering infant feeding as a multicomponent experience in relation to growth, combining both milk feeding and method of CF. This relationship may be explained by differences in maternal feeding style or diet consumed.     

Influence of feeding regimens on non-invasive inferior vena cava and hepatic vein velocity measurements in infants

The aim of this study was to investigate the effects of feeding type and osmotic load on intravascular volume status. Ninety term, healthy infants 2 mo of age were included in the study. The breastfed and formula-fed groups each consisted of 45 infants. Echocardiographic examination was performed before and after feeding. The collapse index of the inferior vena cava (IVCIC) and right atrial pressure (RAP) were calculated. No statistically significant differences were found between before- and after-feeding values of IVCIC, RAP and hepatic vein velocities in breastfed infants. In the formula-fed group, after-feeding values of IVCIC were significantly lower and RAP, hepatic vein systolic and diastolic velocities were significantly higher compared to the before-feeding values. Most of the mothers (78%) were unsuccessful at preparing the formula at appropriate concentrations. No statistically significant differences were found between the before- and after-feeding values of IVCIC, RAP and hepatic vein velocities in infants being fed appropriately prepared formula. The after-feeding values of hepatic vein velocities were higher than those of before-feeding values; after-feeding values of IVCIC were lower than before-feeding values in infants being fed highly concentrated formula. Conclusion: The values of inferior vena cava indices and hepatic vein velocities were not effected by feeding in infants receiving appropriately concentrated formula, like those of infants receiving breast milk. However, feeding with highly concentrated formula may cause intravascular volume expansion.     

Growth of infants with IgE-mediated cow''s milk allergy fed different formulas in the complementary feeding period

Observational studies have shown that allergic infants, irrespective of the type of diet, show various degrees of growth depression in the first year of life. We investigated whether the type of milk in the complementary feeding period (6-12 months of age) is associated with differences in the increase of standardized growth indices (weight-for-age, WA; length-for-age, LA; and weight-for-length, WL, z-scores) in infants with cow's milk allergy (CMA). Infants with immunoglobulin E-mediated CMA breastfed at least 4 months and progressively weaned in the 5- to 6-month period were randomly assigned to three special formulas, a soy formula (n = 32), a casein hydrolysate (n = 31), and a rice hydrolysate (n = 30). A fourth, non-randomized group was made up by allergic infants still breastfed up to 12 months (n = 32). Groups were compared for WA, LA, and WL z-scores at 6, 9 and 12 months of age. All groups showed low WA and LA z-scores at 6 months of age. Infants fed hydrolyzed products showed a trend toward higher WA z-score increments in the 6- to 12-month period. The use of casein- and rice-based hydrolyzed formulas resulted in higher changes in WA compared with soy formula. Further research should be aimed at optimizing the dietary needs and feeding regimens for infants with CMA.     

Effects of formula protein level and ratio on infant growth, plasma amino acids and serum trace elements. I. Cow's milk formula

The optimum level and ratios of protein to be used in cow's milk formula has recently been under discussion. Healthy term infants were fed from birth exclusively human milk or a formula that varied in protein level or whey: casein ratio: (A) 1.4 g/dl; 55:45, (B) 1.5 g/dl; 55:45, (C) 1.3 g/dl; 55:45, (D) 1.4 g/dl; 60:40, (E) 1.4 g/dl; 20:80. Infants were followed for 12 weeks and blood samples were taken at 2, 4, 8 and 12 weeks. Anthropometric indices did not show any significant differences among groups. Plasma amino acid and BUN levels of the C group were closest to the breast-fed group, while the formula with the highest protein level (B) resulted in high values for some amino acids. When comparing the formulas with 1.4 g protein/dl, the high casein group had the lowest plasma tryptophan levels. Taurine was added to all formulas at a level similar to that of breast milk; plasma taurine levels were similar for all groups. All formulas contained 0.7 mg iron and 0.7 mg zinc/dl; no differences were found among the groups in hematological indices or serum trace elements. These data show that feeding a formula with 1.3 g protein/dl and 55:45 whey: casein ratio from birth will result in growth and metabolic indices similar to those of breast-fed infants, although some plasma amino acid levels are not identical, 1990.     

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.     

Effects of Formula Protein Level and Ratio on Infant Growth, Plasma Amino Acids and Serum Trace Elements I. Cow's Milk Formula

Abstract. The optimum level and ratios of protein to be used in cow's milk formula has recently been under discussion. Healthy term infants were fed from birth exclusively human milk or a formula that varied in protein level or whey:casein ratio: (A) 1.4 g/dl; 55:45, (B) 1.5 g/dl; 55:45, (C) 1.3 g/dl; 55:45, (D) 1.4 g/dl; 60:40, (E) 1.4 g/dl; 20:80. Infants were followed for 12 weeks and blood samples were taken at 2, 4, 8 and 12 weeks. Anthropometric indices did not show any significant differences among groups. Plasma amino acid and BUN levels of the C group were closest to the breast-fed group, while the formula with the highest protein level (B) resulted in high values for some amino acids. When comparing the formulas with 1.4 g protein/dl, the high casein group had the lowest plasma tryptophan levels. Taurine was added to all formulas at a level similar to that of breast milk; plasma taurine levels were similar for all groups. All formulas contained 0.7 mg iron and 0.7 mg zinc/dl; no differences were found among the groups in hematological indices or serum trace elements. These data show that feeding a formula with 1.3 g protein/dl and 55:45 whey: casein ratio from birth will result in growth and metabolic indices similar to those of breast-fed infants, although some plasma amino acid levels are not identical, 1990.     

An infant formula free of glycomacropeptide prevents hyperthreoninemia in formula-fed preterm infants

BACKGROUND: Hyperthreoninemia is a well-known phenomenon in infants fed a whey protein-predominant formula. Sweet whey is commonly used for the production of these whey-predominant infant milk formulas. Sweet whey contains not only whey proteins but also the threonine-rich glycomacropeptide (GMP). In the current study, an experimental formula based on acid whey without GMP and a formula based on sweet whey with GMP (threonine content 17.2% higher than in the experimental formula) but otherwise with identical composition were tested with particular respect to threonine metabolism. METHODS: Fourteen preterm infants appropriate for gestational age were enrolled in this randomized cross-over study. After a feeding period of at least 7 days, the nutrition of each infant was switched to the other formula for the second feeding period. At the end of each feeding period, the concentrations of creatinine and amino acids in the plasma and in the urine were measured. RESULTS: In the plasma, the threonine concentration was significantly lower in the group fed the experimental GMP-free formula than in the group fed the sweet whey formula (P < 0.001). Renal excretion of all essential amino acids was generally very low and less than 2% of the intake, indicating that the kidneys had no marked homeostatic function with respect to plasma amino acid. The plasma concentrations of the threonine metabolites glycine and serine, and that of urea were not influenced by diet. CONCLUSION: Feeding a whey protein-predominant bovine milk produced from acid whey protein reduces significantly the hyperthreoninemia commonly found in formula-fed preterm infants. Thus, acid whey formulas should be recommended for feeding preterm infants.     

Plasma lipids and apolipoproteins in breastfed and formula-fed Swedish infants

This study was carried out to compare plasma lipid pattern in breastfed and formula-fed infants and the effects of exchanging breast milk for formula and of introducing weaning foods. Healthy infants, exclusively breastfed at least until 3 mo, were at this age randomly assigned to infant formulas with similar fat composition. Formula was gradually introduced when breastfeeding was discontinued. One group continued to breastfeed beyond 6 mo of age. All infants received the same weaning foods and were studied between 3 and 12 mo of age. Decreased plasma concentrations of total and low-density lipoprotein cholesterol (TC, LDL-C), apolipoprotein B (apo B) and A1 (p < 0.001), and of high-density lipoprotein cholesterol (p < 0.05) were found when breast milk was exchanged for formula before 6 mo. At this age plasma TC, LDL-C and apo B were lower in formula-fed than in breastfed infants (p < 0.001). These plasma lipids then increased (p < 0.01) when the intake of formula decreased and that of weaning foods increased. However, plasma TC and/or LDL-C remained lower at 12 mo in formula-fed than in breastfed infants (p < 0.05). Our results indicate that the plasma lipid profile of infants is highly responsive to the dietary nutrient intake, as indicated by the decrease in plasma lipids and apolipoproteins when breast milk was exchanged for formula and by the increase in these concentrations when the intake of weaning foods gradually increased.