Distribution of B-6 vitamers in human milk during a 24-h period after oral supplementation with different amounts of pyridoxine.

The relative distribution of B-6 vitamers, separated by reverse-phase liquid chromatography, was examined in human milk during a 24-h period after supplementation with 2.5 or 15 mg pyridoxine hydrochloride. Consistently, pyridoxal (PL) was the predominate vitamer and the most responsive to vitamin B-6 intake. During 3-8 h after supplement ingestion, PL, pyridoxal phosphate, and pyridoxamine concentrations were significantly higher than at other times examined. In the first two periods after supplementation, PL as a percentage of total vitamin B-6 was slightly but significantly higher in milk from the group supplemented with 15 mg than from the group supplemented with 2.5 mg. With the exception of PL, the distribution of B-6 vitamers, expressed as percent of total vitamin B-6, was similar for the two supplemented groups at all times examined. Percentage PL of total vitamin B-6 in milk was approximately 25% lower in unsupplemented than in supplemented women.

Evaluation of test-weighing for the assessment of milk volume intake of formula-fed infants and its application to breast-fed infants.

Test-weighing (TW) was evaluated in formula-fed (FF) infants by comparison with direct measurement (DM) of formula intake during a 24 h period at 1, 2, 4 and 6 mo of age. Formula intakes estimated by TW ranged from 87 to 93% of those determined by DM over the 6-mo period. During the study period the number of feedings per day decreased but were not significantly different for FF and BF infants. Volume of intake per feeding by FF infants increased significantly during the 6-mo period whereas milk intakes of BF infants were not different at the four ages studied. These data indicated that when the number of daily feedings decreased with age, FF infants increased their volume of intake per feeding whereas BF infants did not adjust their intakes. Mean volume of milk intake at 4 and 6 mo, estimated by TW, was significantly greater in FF infants compared to breast-fed (BF) infants matched for age and size. Data from this study indicated clearly that when milk intakes of BF infants are compared to those of FF infants, both groups of infants should be test-weighed.

PIP: Test-weighing (TW) was evaluated in formula-fed (FF) infants from a University community in Indiana by comparison with direct measurement (DM) of formula intake during a 24 hour period at 1, 2, 4, and 6 months of age. Formula intakes estimated by TW ranged from 87 to 93% of those determined by DM over the 6-month period. During the study period the number of feedings per day decreased but were not significantly different for FF and BF infants. Volume of intake per feeding by FF infants increased significantly during the 6-month period whereas milk intakes of BF infants were not different at the 4 ages studied. These data indicate that when the number of daily feedings decreased with age, FF infants increased their volume of intake per feeding whereas BF infants did not adjust their intakes. Mean volume of milk intake at 4 and 6 months, estimated by TW, was significantly greater in FF infants compared to BF infants matched for age and size. Data from this study indicate clearly that when milk intakes of BF infants are compared to those of FF infants, both groups of infants should be test-weighed.

Effects of vitamin B6 intake on nutriture and growth of young infants.

Vitamin B6 is critical to normal development; however, the requirement for adequate nutriture of the human infant is based on limited experimental data. In this study vitamin B6 intakes of breast-fed (BF) and formula-fed (FF), healthy, term infants were related to levels of pyridoxal phosphate (PLP) in their plasma at 1, 2, 4, and 6 mo of age. Mothers of BF infants were supplemented with either 2.5 or 15.0 mg pyridoxine . hydrochloride (PN . HCl)/d. Growth was similar for FF and BF infants and was within normal ranges over the 6 mo period. Plasma PLP in cord blood was similar in BF and FF infants; however, at 1-5 d of age and at each subsequent age studied, levels of plasma PLP were significantly higher in FF infants than in BF. Lowest PLP values were for BF infants of mothers who received 2.5 mg PN . HCl/d. Mean plasma PLP decreased with age and was not correlated to vitamin B6 intakes except at 1 mo of age. At this age, vitamin B6 intake of BF infants whose mothers received 2.5 mg PN . HCl/d was only 0.1 mg B6/d. The consequences of this are uncertain; however, plasma PLP levels of the infants were low and reflected their intakes of vitamin B6.

Selenate fortification of infant formulas improves the selenium status of preterm infants.

The purpose of this study was to determine whether selenate fortification of infant formula would improve the selenium status of relatively well, growing, preterm infants during the first 12 wk of enteral feeding. A high-selenium group (n = 7, mean body weight = 1312 g) received selenate-fortified preterm and full-term infant formulas containing 0.36 and 0.22 mumol Se/L, respectively, and a low-selenium group (n = 10, mean body weight = 1262 g) received non-selenium-fortified preterm and full-term infant formulas containing 0.12 and 0.11 mumol Se/L, respectively. There were no significant differences in growth between the two groups throughout the study. The high-selenium group had significantly greater mean selenium intakes than did the low-selenium group from weeks 2 to 12. Plasma selenium concentrations decreased over the study period in the low-selenium group. Plasma selenium-dependent glutathione peroxidase activity was greater in the high-selenium group at week 12 only. Red blood cell selenium concentrations decreased over time in both groups and were significantly greater in the high-selenium group at weeks 4, 8, and 12. Plasma selenium concentrations were significantly correlated with plasma glutathione peroxidase activity for all infants on study day 1 and at weeks 4 and 12. Selenium intake of all infants was significantly correlated with plasma glutathione peroxidase activity at 12 wk. Selenate fortification of infant formulas can improve the selenium status of preterm infants. Current selenium contents of infant formulas and recommendations for dietary intakes of selenium for some preterm infants may be inadequate.

Effects of human milk or formula feeding on the growth, behavior, and protein status of preterm infants discharged from the newborn intensive care unit.

The growth, behavior, and protein status of 59 healthy preterm (mean gestational age 30 wk) infants fed either human milk or one of three infant formulas were studied post-discharge from the hospital. Formula-fed infants received either a standard term formula, a standard preterm formula, or an experimental preterm formula from discharge to 8 wk of age. From 8 to 16 wk, all formula-fed infants received the standard term formula. At 2, 8, and 16 wk, anthropometric, dietary intake, blood biochemistry, amino acid, and Brazelton Neonatal Behavioral Assessment measurements were evaluated. Weights, lengths, and head circumferences were similar for all feeding groups at discharge. After discharge all formula-fed infants were heavier than human milk-fed infants. Length and head circumference values and plasma urea nitrogen and retinol-binding protein concentrations were not different among dietary groups. Formula-fed infants had higher plasma concentrations of numerous amino acids compared with those of human milk-fed infants during the first 8 wk but not at 16 wk. There were no differences among the feeding groups in the Brazelton assessment. This study found little effect on the growth or behavioral or protein status of preterm infants discharged from the hospital who were fed either human milk or formulas designed for term or preterm infants.

Fatty acid composition of mature human milk of Egyptian and American women.

Fatty acid composition of mature human milk of rural Egyptian and American women was determined by gas-liquid chromatography. Milk of Egyptian women contained significantly higher percentages of capric, lauric, myristic, linoleic and arachidonic acids, saturated fatty acids (SFA), and polyunsaturated fatty acids (PUFA). Conversely, milk of American women contained higher percentages of stearic and oleic acids, total unsaturated fatty acids, and monounsaturated fatty acids. The PUFA:SFA ratio in Egyptian samples was 0.54 +/- 0.18 compared to 0.47 +/- 0.22 in American samples. Increased percentages of medium-chain SFA in Egyptian milk suggested increased mammary gland lipid synthesis. Analysis of Egyptian diets indicated high-carbohydrate and low-fat intakes may have resulted in limited availability and incorporation of dietary fatty acids into milk triglycerides. Thus, increased percentages of medium-chain SFA observed in Egyptian milk may reflect mammary gland synthesis in an attempt to maintain lipid concentrations in milk.

Effectiveness of casein hydrolysate feedings in infants with colic.

This study found that two casein hydrolysate formulas varying in composition were equally effective in managing colicky symptoms associated with protein sensitivity. Both hydrolysate formulas were associated with a significant, comparable reduction in crying duration and intensity from baseline in 15 of 22 infants with complete data. Subsequent challenge data suggest that the population studied were infants experiencing colicky symptoms due to protein sensitivity. A greater proportion of infants showed a positive reaction (> or = 1.5 h of crying/d) to the protein challenges than the placebo challenge, and crying was rated as more intense during whey and milk protein challenges.

A micromethod for determination of plasma pyridoxal phosphate and its use in assessment of storage stability of the vitamer.

A widely used macromethod employing tyrosine apodecarboxylase for measurement of pyridoxal phosphate (PLP) concentration in 0.5-1.0-ml plasma was modified to a microscale utilizing 0.1-ml plasma. Mean PLP levels in 12 plasma samples were 160.6 +/- 32.8 pmol/ml (mean +/- SD) when analyzed by the macromethod, and were not significantly different compared to those obtained by the micromethod (158.4 +/- 28.2 pmol/ml). Results of the two methods were significantly correlated (r = +0.97, p less than 0.001). Plasma PLP concentrations of 11 samples determined by the micromethod (means = 151.8 +/- 30.0 pmol/ml) were similar and significantly correlated (r = +0.95, p less than 0.001) to levels measured in the same samples 1-2 years earlier (means = 145.1 +/- 26.2 pmol/ml). This suggests that plasma PLP content of the samples was stable for up to 2 years of storage when the micromethod was utilized for analysis. The strong significant correlation between macro- and micromethods attests that the micromethod is a reliable alternative to the macromethod. The micromethod is useful in instances where only small samples of plasma are available for measurement of PLP.

Zinc homeostasis in healthy infants fed a casein hydrolysate formula.

BACKGROUND: The results of earlier, nonquantitative studies suggested that absorption of zinc from a semielemental (casein hydrolysate) formula was inferior to absorption from a cow's milk-based formula. The objective of this study was to compare fractional, total and net zinc absorption, and fecal excretion of endogenous zinc in the same healthy young infants when fed a casein hydrolysate versus cow's milk-based formula. METHODS: Fractional absorption of zinc and fecal excretion of endogenous zinc were determined from measurement of cumulative fecal excretion of unabsorbed tracer and by an isotope dilution technique, respectively, after oral administration of a 70Zn tracer with all formula feedings for 1 day. Six infants were assigned randomly to receive the test or control formula, and the other formula was administered 2 to 5 weeks later. RESULTS: Mean (+/-SD) fractional absorption of zinc from the casein hydrolysate formula (0.47 +/- 0.17) was double that from the cow's milk-based formula (0.22 +/- 0.04; P = 0.01) with a correspondingly greater total zinc absorption (3.23 +/- 1.67 mg Zn/day vs. 1.55 +/- 0.55 mg Zn/day; P = 0.05). Because the excretion of endogenous zinc in the feces did not differ between formulas (0.90 +/- 0.44 mg Zn/day vs. 0.91 +/- 0.29 mg Zn/day), net absorption of zinc was also higher with the casein hydrolysate formula (2.33 +/- 1.65 mg Zn/day vs. 0.81 +/- 0.67 mg Zn/day; P = 0.02). CONCLUSIONS: Retention of zinc appeared to be adequate to meet the needs for growth during feeding with cow's milk-based formula and was more than adequate during short-term feeding with the casein hydrolysate formula.

Growth and protein status of term infants fed soy protein formulas differing in protein content.

OBJECTIVE: The purpose of this study was to compare growth and protein status of healthy term infants from 2 to 112 days of age fed a commercially available soy-based formula (IS) and a similar formula (EF) containing less protein (2.91 vs 2.45 g/100 kcal). DESIGN: A controlled, randomized, blind parallel clinical trial was conducted in 32 male and 32 female infants. Infants were enrolled at 2 days of age, and their assigned formula was their only feeding to 112 days of age. At this time their weight, length, and head circumference were measured. Weight, length, and head circumference were measured and formula intake, formula intolerance and stool characteristics were recorded at 8, 28, 56, and 112 days of age. Plasma urea nitrogen (PUN), total protein, albumin, and transthyretin were determined at 56 and 112 days. RESULTS: There were no statistically significant differences in weight, length, head circumference, or gains in these measures. PUN concentration was significantly lower in infants fed EF than IS at 56 and 112 days. Plasma total protein, albumin, and transthyretin concentrations were not different between the two feeding groups at the two testing periods. Tolerance to the two formulas was similar. Stool characteristics did not differ between the two groups. CONCLUSION: A soy-based formula containing 2.45 g protein/100 kcal and approximately 640 mumol of total sulfur containing amino acids/100 kcal adequately meets the protein needs of term infants from 2 to 112 days of age.

Evaluation of the effect of a fiber-enriched formula on infant colic.

Because infants with colic appear to have abdominal pain similar to that of adults with irritable bowel syndrome, who may benefit from the addition of fiber to their diet, we tested whether fiber added to infant formula would alleviate colic. Twenty-seven normal, term infants (aged 2 to 8 weeks; 14 girls) with colic, defined as crying plus fussing for more than 3 hours a day for at least 3 days of a 6-day baseline period, were enrolled. Infants were randomly assigned in 9-day periods to a sequence of placebo (Isomil formula) followed by fiber-supplemented formula (Isomil plus soy polysaccharide) (n = 12) or the reverse (n = 15). Daily diaries of crying, fussing, sleeping, formula, intake, and stooling were kept. Twenty-two infants completed three lactulose breath hydrogen tests at the end of the baseline period and after each study period. The crossover trial was followed by 30 to 35 days of use of the study formula chosen by the parents as most beneficial but unknown to the investigators. Growth was monitored throughout. Serum cholesterol, calcium, phosphate, albumin, iron, and zinc concentrations were measured at the conclusion. There were no significant differences in average daily time spent by the infants in fussing and crying during ingestion of the fiber-supplemented formula. However, parents of 18 of 27 infants chose fiber-supplemented formula as most beneficial in ameliorating symptoms of colic. While the infants were consuming fiber-supplemented formula, stool frequency increased, and breath hydrogen excretion increased significantly, in response to lactulose. Growth and serum biochemical measurements were normal in all infants. Supplementation of infant formula with the level of soy polysaccharide used in this study may have reduced crying and fussing in some infants but did not affect colicky behavior in the majority of infants, who continued to cry and fuss excessively.