Free amino acids in full-term and pre-term human milk and infant formula

OBJECTIVE: Although the nutritional value of human milk has been thoroughly studied, few reports describing its free amino acid (FAA) content have been published. Although infant formulas are designed to approximate the nutrient composition of human milk, the content and concentration of free amino acids are unknown. We compared the FAA concentrations of milk from mothers of preterm and full-term infants with those in several infant formulas. METHOD: Human milk was obtained during three different stages of lactation (colostral, transitional and mature milk). Sixty-seven samples were collected from 44 healthy mothers of term infants and 23 mothers of premature infants 29 to 36 weeks gestation (mean 33 weeks). Two brands of powdered term formula (TF-A and TF-B) and two brands designed for preterm infants (PTF-A and PTF-B )were also studied. Ion exchange chromatography was used for free amino acid analysis. RESULTS: The mean concentration of total FAA in human milk was significantly higher than any of the infant formulas (8139 micromol/L for pre-term human milk; 3462 micromol/L for full term human milk; TF-A, 720 micromol/L; TF-B, 697 micromol/L; PTF-A, 820 micromol/L; PTF-B, 789 micromol/L) (P <0.01). FAA concentration in term and premature human colostral milk was significantly higher than in human transitional and mature milks (P <0.01). In comparing individual FAAs, there were significant differences in concentrations between term human milk and preterm milk except for phosphoethanolamine, hydroxyproline, asparagine, and alpha-amino-eta-butyric acid. There were significant differences in all FAA concentrations between all human milks and infant formulas (P <0.05), but no significant differences were found among the study formulas. CONCLUSION: The concentration of FAA is high in human colostral milk and decreases through the transitional and mature milk stages. FAA is higher in all human milks than in infant formulas.     

Vitamin E status in preterm infants fed human milk or infant formula

Vitamin E status was assessed in 36 infants with birth weights less than 1500 gm who were assigned randomly to receive one of three sources of nutrition: milk obtained from mothers of preterm infants (preterm milk), mature human milk, or infant formula. Infants in each dietary group were further assigned randomly to receive iron supplementation (2 mg/kg/day) beginning at 2 weeks or to receive no iron supplementation. All infants received a standard multivitamin, providing 4.1 mg alpha-tocopherol daily. Serum vitamin E concentrations at 6 weeks were significantly related both to type of milk (P less than 0.0001) and to iron supplementation (P less than 0.05). Infants fed preterm milk had significantly higher serum vitamin E levels than did infants fed mature human milk, and both groups had significantly higher levels than did those fed formula. Ratios of serum vitamin E/total lipid were also significantly greater for infants fed human milks than for those fed formula. The addition of iron to all three diets resulted in significantly lower serum vitamin E levels at 6 weeks (P less than 0.05); however, only in the group fed formula was there evidence of vitamin E deficiency. Preterm milk with routine multivitamin supplementation uniformly resulted in vitamin E sufficiency in VLBW infants whether or not iron was administered.     

Microwave heating of infant formula and breast milk

Heating infant formula and breast milk in a microwave oven has become a common practice in many households. A review of the literature is presented to ascertain if there is evidence to support the safety of this practice, as well as to determine if microwaving affects the nutritional content of the heated milk. The results of a local community's survey are presented, which assesses parental use of microwave ovens in the heating of infant formula and parents' knowledge of the potential hazards of this practice.     

Growth and development of premature infants fed predominantly human milk, predominantly premature infant formula, or a combination of human milk and premature formula

BACKGROUND: In a recent meta-analysis, human milk feeding of low birth-weight (LBW) infants was associated with a 5.2 point improvement in IQ tests. However, in the studies in this meta-analysis, feeding regimens were used (unfortified human milk, term formula) that no longer represent recommended practice. OBJECTIVE: To compare the growth, in-hospital feeding tolerance, morbidity, and development (cognitive, motor, visual, and language) of LBW infants fed different amounts of human milk until term chronologic age (CA) with those of LBW infants fed nutrient-enriched formulas from first enteral feeding. METHODS: The data in this study were collected in a previous randomized controlled trial assessing the benefit of supplementing nutrient-enriched formulas for LBW infants with arachidonic acid and docosahexaenoic acid. Infants (n = 463, birth weight, 750-1,800 g) were enrolled from nurseries located in Chile, the United Kingdom, and the United States. If human milk was fed before hospital discharge, it was fortified (3,050-3,300 kJ/L, 22-24 kcal/oz). As infants were weaned from human milk, they were fed nutrient-enriched formula with or without arachidonic and docosahexaenoic acids (3,300 kJ/L before term, 3,050 kJ/L thereafter) until 12 months CA. Formula fed infants were given nutrient-enriched formula with or without added arachidonic and docosahexaenoic acids (3,300 kJ/L to term, 3,050 kJ/L thereafter) until 12 months CA. For the purposes of this evaluation, infants were categorized into four mutually exclusive feeding groups: 1) predominantly human milk fed until term CA (PHM-T, n = 43); 2) >/= 50% energy from human milk before hospital discharge (>/= 50% HM, n = 98); 3) < 50% of energy from human milk before hospital discharge (< 50% HM, n = 203); or 4) predominantly formula fed until term CA (PFF-T, n = 119). RESULTS: PFF-T infants weighed approximately 500 g more at term CA than did PHM-T infants. This absolute difference persisted until 6 months CA. PFF-T infants were also longer (1.0-1.5 cm) and had larger head circumferences (0.3-1.1 cm) than both PHM-T and >/= 50% HM infants at term CA. There was a positive association between duration of human milk feeding and the Bayley Mental Index at 12 months CA (P = 0.032 full and P = 0.073 reduced, statistical models) after controlling for the confounding variables of home environment and maternal intelligence. Infants with chronic lung disease fed >/= 50% HM until term CA (n = 22) had a mean Bayley Motor Index about 11 points higher at 12 months CA compared with infants PFF-T (n = 24, P = 0.033 full model). CONCLUSION: Our data suggest that, despite a slower early growth rate, human milk fed LBW infants have development at least comparable to that of infants fed nutrient-enriched formula. Exploratory analysis suggests that some subgroups of human milk fed LBW infants may have enhanced development, although this needs to be confirmed in future studies.     

A human milk formula

In view of the possible deficits in the energy value and protein content of human milk when used for feeding low birth weight preterm neonates, a method has been devised suitable for use in a human milk bank for making milk formulae from human milk products. Human milk formula (HMF) is produced by adding, to whole human milk, human cream, obtained by separation by centrifugation, together with salt-free and lactose-free human milk protein, extracted by simple dialysis and freeze-drying. This human milk formula is, therefore, enriched in energy, human milk fat, protein and salts (which may be added), to approach the current concept of an ideal milk formula(e) for preterm infants. In addition, the increased concentration of antimicrobial proteins achieved in HMF may offset any losses in these proteins caused by pasteurisation.     

Enterobacter sakazakii and other bacteria in powdered infant milk formula

Recently there has been considerable concern related to the presence of bacteria, in particular Enterobacter sakazakii, in powdered infant formula milk. This paper considers the bacteria in these products at point of sale, with reference to current microbiological testing and the need for good hygienic practice in their subsequent preparation before feeding. The ingestion of raised numbers of E. sakazakii resulting from temperature abuse after reconstitution is highlighted as well as the uncertain routes of E. sakazakii product contamination.     

Cow's milk-based formula, human milk, and soya feeds in acute infantile diarrhea: a therapeutic trial

Acute infantile diarrhea is often managed by introducing lactose-free diets empirically from the time of diagnosis, in addition to conventional rehydration therapy. In order to assess the efficacy of this, a therapeutic trial was undertaken in which hospitalized gastroenteritis patients previously on milk-formula feeds were randomly fed, from the time of admission, either their original feed or a lactose-free soya preparation; patients previously on human milk with or without a supplement continued to receive this during their diarrheal illness. The results show that in nonrotaviral gastroenteritis, there is no difference in the duration of the illness irrespective of the type of feed given. In rotaviral gastroenteritis, continued breast-feeding significantly reduces the duration of acute diarrhea, while lactose-free soya feeds do not lead to a significant reduction in the duration of the illness when compared to cow's milk-formula feeds. Hence, it is concluded that (a) breast-feeding should be continued during an episode of infantile diarrhea, and that (b) empirical use of soya preparations from the time of hospital admission is not justified; however, the latter should be considered in infants whose purging rate goes up or diarrheal disease severity worsens 3 to 4 days after the onset of diarrhea or hospital stay and who are passing significant amounts of reducing sugars in their stool.     

Prebiotic effect of fructo-oligosaccharide supplemented term infant formula at two concentrations compared with unsupplemented formula and human milk

BACKGROUND: Human milk components, including oligosaccharides, affect the gastrointestinal flora of infants. Previous studies in adults have demonstrated that fructo-oligosaccharides increase potentially beneficial fecal bacteria, including bifidobacteria. The purpose of this study was to determine the prebiotic effect of infant formula supplemented with fructo-oligosaccharides. METHODS: Healthy term infants 2 to 6 weeks of age were enrolled in a 5-week, prospective, randomized, crossover, single-site study with a nonrandomized human milk comparator group. Washout weeks preceded and followed a week of feeding with fructo-oligosaccharide-supplemented formula (1.5 or 3.0 g/L). Stool specimens were quantitatively cultured weekly for bacteroides, lactobacilli, bifidobacteria, clostridia and enterococci and were tested for Clostridium difficile toxin. RESULTS: Seventy-two of 87 infants completed the trial; 58 were formula fed and 14 were human milk fed. Mean counts of bifidobacteria and lactobacilli were similar in all groups at entry and no group experienced a significant change in counts with fructo-oligosaccharide supplementation. After 7 days of fructo-oligosaccharide supplementation the bifidobacteria counts were greater in the 1.5 g/L fructo-oligosaccharide formula group than in the human milk fed or 3.0 g/L fructo-oligosaccharide formula groups. Formula-fed infants had higher counts of enterococci and bacteroides before fructo-oligosaccharide supplementation, and these counts did not change after supplementation. Clostridium counts increased 7 days after supplementation in the 1.5 g/L fructo-oligosaccharide formula group (P = 0.0356). No human milk fed infants had C. difficile toxin in stools. Fructo-oligosaccharide (3.0 g/L) supplementation resulted in more frequent and significantly softer stools. CONCLUSIONS: Infant formula supplemented with 1.5 or 3.0 g/L fructo-oligosaccharides was safe but had minimal effect on fecal flora and C. difficile toxin.     

Urinary excretion of lactose and oligosaccharides in preterm infants fed human milk or infant formula

At present, not much is known about the absorption and metabolism of human milk (HM) oligosaccharides in term and preterm infants. We investigated the renal excretion of lactose and complex oligosaccharides in preterm infants fed HM ( n = 9, mean actual body weight 2290 g) or a cow's milk-based infant formula ( n = 9, mean actual body weight 2470 g). We found that the renal excretion of lactose in HM-fed infants was slightly lower than in formula-fed infants (14.0 ± 7.4 versus 20.4 ± 8.7 mg kg^-1 day^-1, mean ± SD). The excretion of neutral sugars deriving from oligosaccharides was similar in HM-fed and formula-fed infants (3.8 ± 2.1 versus 2.9 ± 0.9mgkg^-1 day^1-); the difference between means was not statistically significant. The separation and characterization of oligosaccharides by high-pH anion exchange chromatography with pulsed amperometric detection (HPAE-PAD) and subsequent analysis by fast atom bombardment-mass spectrometry (FAB-MS) revealed a more complex pattern in HM-fed infants compared to the formula-fed group. Lactose-derived oligosaccharides characteristic for HM (e.g lacto- N -tetraose, and lacto- N -fucopentaoses I and II) were excreted in HM-fed but not in formula-fed infants. These results indicate that nutrition has a significant impact on the oligosaccharide composition in urine of preterm infants.     

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.     

Randomized, double-blind comparison of growth in infants receiving goat milk formula versus cow milk infant formula

OBJECTIVE: To compare growth of infants fed goat milk infant formula (GMF) or cow milk infant formula (CMF) and to compare tolerability and safety of the two formulas. METHODS: The study was conducted in Auckland, New Zealand. This was a double-blind randomized controlled trial. Newborn term infants were randomized within 72 h of birth to GMF or CMF. Milk formula powder in single serve sachets were reconstituted and fed to infants from trial commencement until age 168 days. No other formula given from randomization until age 168 days. Infant weight, length and head circumference were measured at birth and age 14, 28, 56, 84, 112, 140 and 168 days. Bowel motion frequency and consistency, sleeping and crying patterns and adverse events were also measured. RESULTS: Seventy-two infants were randomized, 36 each to GMF or CMF, with 62 infants completing the intervention. At enrollment the average weight of infants in the GMF group (mean +/- SD) was 3.33 +/- 0.43 kg and in the CMF group 3.43 +/- 0.47 kg; and at study completion 8.07 +/- 0.90 kg (GMF) and 7.87 +/- 0.99 kg (CMF). The difference in average weight gain over the study period for the GMF group versus the CMF group was not significant (+309 g; 95% CI = -49 to +668, P = 0.09). Median daily bowel motion frequency was greater in the GMF group than the CMF group (2.4 vs 1.7, P = 0.01). There were no group differences in bowel motion consistency, duration of crying, ease of settling, or frequency of adverse events. CONCLUSION: Growth of infants fed GMF is not different to that of infants-fed CMF.     

Physiological aspects of human milk lipids and implications for infant feeding: a workshop report

The biology of human milk and lactation helps understand the physiology of breastfed infants. The compositional and biological effects of human milk lipids have received considerable interest regarding their modulating effects on growth, metabolism and functions of the cardiovascular, immune and nervous system. CONCLUSION: This paper describes key aspects of a scientific workshop focused on current knowledge, unresolved questions and future research needs in the area of human milk lipids and their physiological effects in infants.     

Calcium retention from milk-based infant formulas, whey-hydrolysate formula, and human milk in weanling rhesus monkeys

An adequate supply of calcium is important for normal bone mineralization in infants. Special infant formulas have been developed to treat infants with a high risk of developing allergy. Similar to other diets, it is important that these products are nutritionally adequate. We have measured calcium retention from a new formula based on whey hydrolysate and compared it with conventional formulas, using extrinsic labeling with calcium 47 and the weanling rhesus monkey as an animal model. Retention of calcium was similar for all formulas studied: 45% +/- 4% (mean +/- SEM) from whey-hydrolysate, 47% +/- 2% from whey-predominant, and 53% +/- 7% from casein-predominant formula. Calcium retention from human milk, 72% +/- 3%, was significantly higher than from formula. Using these retention values and the calcium concentrations of the diets, infant formula and human milk deliver approximately equal amounts of calcium to the infant.