HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Sandström, O. Articles by Hernell, O. Search for Related Content PubMed PubMed Citation Articles by Sandström, O. Articles by Hernell, O. Agricola Articles by Sandström, O. Articles by Hernell, O.

Effects of -lactalbumin–enriched formula containing different concentrations of glycomacropeptide on infant nutrition ^1,2,3

¹ From the Department of Clinical Sciences, Pediatrics, Umeå University, Umeå, Sweden (OS and OH); the Department of Nutrition, University of California, Davis, CA (BL); and Arla Foods Ingredients, Aarhus, Denmark (GG)

² Supported by Arla Foods Ingredients, Aarhus, Denmark.

³ Address reprint requests and correspondence to O Hernell, Department of Clinical Sciences, Pediatrics, Umeå University, S-901 85 Umeå, Sweden. E-mail: olle.hernell{at}pediatri.umu.se.

	ABSTRACT

TOP ABSTRACT INTRODUCTION SUBJECTS AND METHODS RESULTS DISCUSSION REFERENCES

 
Background: Formula-fed infants have growth and plasma amino acid patterns different from those of breastfed infants.

Objective: -Lactalbumin is a major protein in human milk, and the addition of bovine -lactalbumin to infant formula has been proposed to modify the plasma amino acid pattern of the recipient infant, possibly allowing a reduction in the protein content of the formula, which may affect growth.

Design: We compared breastfed infants and infants fed standard formula or -lactalbumin–enriched formulas (25% of protein) with glycomacropeptide accounting for 15% or 10% of the protein. The protein content of each formula was 13.1 g/L. Ninety-six infants aged 6 ± 2 wk were recruited. Anthropometric measures were recorded, and interviews were conducted at enrollment and monthly until 6 mo of age. Blood samples were collected at enrollment and at 4 and 6 mo.

Results: Formula intake did not differ between groups, and weight gain in the -lactalbumin–enriched formula groups were similar to that of the breastfed infants. The standard formula group gained significantly more weight than did the breastfed infants. All formula-fed infants had significantly higher plasma concentrations of most essential amino acids at 4 and 6 mo than did the breastfed infants, and serum urea nitrogen was also higher in the formula-fed infants. Insulin and leptin concentrations did not differ between groups.

Conclusions: Compared with standard formula-fed infants, infants fed formula with a modified protein composition had growth patterns more similar to those of breastfed infants. All formula-fed groups had plasma amino acid concentrations similar to or higher than those of breastfed infants. This indicates that the protein content of -lactalbumin–enriched formula can be further reduced, which should be evaluated.

	INTRODUCTION

TOP ABSTRACT INTRODUCTION SUBJECTS AND METHODS RESULTS DISCUSSION REFERENCES

 
The use of cow milk as the protein source in infant formula results in a casein-dominant formula, which differs from the whey protein predominance in human milk. Consequently, the whey:casein ratio of infant formula has been adjusted to resemble that of human milk (60:40) by the addition of whey protein concentrate. Despite the adjustment, there are considerable differences in the protein composition of infant formula and human milk. A large part of that difference is due to a higher concentration of -lactalbumin in human than in bovine milk. Furthermore, bovine whey contains a high concentration of β-lactoglobulin, which is absent in human milk (1). Current dairy technology makes it possible to produce bovine whey fractions that are reduced in β-lactoglobulin and enriched in -lactalbumin (2, 3). Adding bovine -lactalbumin to infant formula has been proposed, because it modifies the plasma amino acid pattern in infants, making it more similar to that of breastfed infants (4-6).

The optimal protein content of infant formula is a matter of controversy. Although there is general agreement that the protein content in currently used formula exceeds infant requirements, the extent to which protein can be safely reduced is not clear. This is because some amino acids, notably tryptophan and arginine, become limiting by the current protein composition of formula. The alternatives are to maintain a protein concentration higher than necessary or reduce the protein concentration and add free amino acids. It has been argued that excess protein places unnecessary strain on immature metabolic organs (7, 8), that adding free amino acids appears unphysiological, and that the metabolic consequences of doing so are largely unknown. A more physiologically relevant approach would be to modify the protein composition of formula to make it more similar to human milk, which would presumably lead to plasma amino acid patterns more similar to those of breastfed infants. The amino acid composition of -lactalbumin is well balanced, with a high proportion of certain essential amino acids. Increasing the -lactalbumin concentration in formula, and thus concentrations of these essential amino acids, would allow a reduction of the total protein concentration and result in a more balanced plasma amino acid profile in formula-fed infants (9). In addition to being a source of amino acids, -lactalbumin is believed to have several physiologic effects, such as antimicrobial activity, enhanced immune function, prebiotic function, and increased trace element absorption (10, 11). Thus, there are several potential benefits of adding -lactalbumin to formula that need to be evaluated in clinical studies.

Glycomacropeptide (GMP) is a large acidic glycoprotein that is cleaved from -casein by pepsin hydrolysis in the stomach. GMP is not present in breast milk, but it is formed during digestion and is believed to have antimicrobial, mineral-absorption-enhancing (12), and prebiotic (11-14) effects. GMP is also formed from bovine -casein by the action of rennet during the manufacturing of cheese and has recently become commercially available (2). Consequently, it is of interest to study the clinical effects of adding GMP to infant formula. In our initial study, we found only minor effects of the experimental formulas studied herein on intestinal microbiota (15).

	SUBJECTS AND METHODS

TOP ABSTRACT INTRODUCTION SUBJECTS AND METHODS RESULTS DISCUSSION REFERENCES

 
Experimental formula
Bovine whey fractions rich in -lactalbumin with various concentrations of GMP were provided by Arla Foods Ingredients (Aarhus, Denmark) and were produced as previously described (2, 3). The formulas were as follows: 1) whey-predominant standard infant formula (11% -lactalbumin, 14% GMP); 2) -lactalbumin-enriched formula (25% -lactalbumin), with GMP accounting for 15% of the protein content (-LAC); and 3) -lactalbumin–enriched formula (25% -lactalbumin), with GMP accounting for 10% of the protein content (RGMP; Table 1).

Study design
Infants aged 6 ± 2 wk were recruited for the study. The infants were exclusively breastfed or exclusively formula fed 1 of the 3 experimental formulas until they were 4 mo of age. At 4 mo of age, the infants were permitted 1–2 Tbsp fruit and/or vegetable puree each day. Subsequent to the initial enrollment visit, an experienced research nurse visited each participating infant when the infant was 2, 3, 4, 5, and 6 mo of age. Anthropometric measurements, structured interviews concerning sleeping time and general well-being, and questionnaires regarding formula intake, bowel habits, stool consistency on the last 3 days before the visit, and morbidity during the whole month were obtained at all visits (15). Formulas were fed with bottles graded to the nearest 5 mL, and parents recorded the volume at the beginning and the end of each meal. Weight was measured with a Seca 835 digital baby scale (Seca, Hamburg, Germany), and recumbent length was measured with a Harpenden infantometer (CMS Weighing Equipment, London, United Kingdom). Knee-heel length was measured with an Infant Knemometer (BK5; FORCE Instituttet. Brøndby, Denmark). Head circumference was measured with a nonstretchable measuring tape. Blood samples were drawn at enrollment and at 4 and 6 mo of age. Blood samples were drawn before a meal, generally 2–4 h after the latest meal.

Hematology and iron status were assessed at the Department of Clinical Chemistry, Umeå University Hospital. Iron status was analyzed by a Sysmex SE 9000 Autoanalyzer (Tillqvist, Kista, Sweden). Hemoglobin was analyzed with a Sysmex Sulfolyser automated hemoglobin reagent (Toa Medical Electronics Co, Ltd, Los Alamitos, CA), and mean corpuscular volume was automatically calculated from the erythrocyte particle concentration and hematocrit. Serum iron (S-Fe) was analyzed by the ferrozine method (Iron kit 1553712 and UIBC kit 1030600; Boehringer Mannheim, Scandinavia AB, Bromma, Sweden). Serum ferritin (S-Ft) was analyzed with an immunoturbidimetric technique (BM/Hitachi 704/717/911; Boehringer Mannheim) calibrated against World Health Organization standard 80–602. Serum urea nitrogen (BUN) was measured with a commercial kit using urease (Sigma, St Louis, MO). Proteins were separated from plasma with 6% sulfosalicylic acid precipitation, and free amino acids were analyzed in the supernatant fluid on a Beckman 6300 amino acid analyzer (Beckman, Mountain View, CA). Plasma insulin and leptin were analyzed by radioimmunoassay (Linco Research, St Louis, MO).

Statistical analysis
SPSS version 11 (SPSS Inc, Chicago, IL) was used for all statistical analyses. Analysis of variance was performed, and Bonferroni post hoc tests were used to adjust for multiple comparisons. Values are expressed as means ± SDs. For those variables measured at study enrollment (anthropometric data, hematology, and iron status), analysis of covariance was used to adjust for differences at baseline. Initial values (6 ± 2 wk) were used as covariates. For variables for which there were differences between males and females, sex was a covariate.

Anthropometric data are reported as mean increments per month, and z scores were compared with a World Health Organization/National Center for Health Statistics reference population (17). Data were converted to z scores by using EPI-INFO version 1.1.1 (Centers for Disease Control and Prevention, Atlanta, GA) and the 2000 Centers for Disease Control and Prevention reference growth data.

	RESULTS

TOP ABSTRACT INTRODUCTION SUBJECTS AND METHODS RESULTS DISCUSSION REFERENCES

 
Eighty (83%) of the 96 recruited infants completed the study. In the standard formula group, 2 infants developed allergies to cow milk protein, and 2 families chose to discontinue participation in the study. In the -LAC group, 2 infants developed allergy to cow milk protein, and one family chose to discontinue participation in the study. In the RGMP group, 1 child developed an allergy to cow milk protein, and 3 families chose to discontinue participation in the study. Five of the breastfed infants dropped out of the study because of inadequate milk production. There were no statistically significant between-group differences in dropout rate or the reasons for doing so. No serious adverse events were recorded for any of the groups. Mean gestational age, birth weight, and recumbent length were similar for the formula-fed and breastfed groups. However, there were significant differences in sex distribution between the groups (Table 2). Post hoc analyses were performed, and we found that amino acid concentrations differed between males and females. Therefore, sex was included as a covariate when plasma amino acid patterns were analyzed. Other variables did not differ significantly between groups.

Table 3

Figure 1

View larger version (19K): [in this window] [in a new window]   FIGURE 1. Mean (±SD) weight-for-age, length-for-age, and head circumference–for-age z scores from enrollment to 6 mo of age. Groups were compared by using ANCOVA (adjusted for baseline values) and a Bonferroni post hoc test. At enrollment the weight-for-age z score was significantly higher for the breastfed group than for the -LAC formula group (P < 0.05). -LAC, -lactalbumin enriched (15% glycomacropeptide); RGMP, -lactalbumin enriched (10% glycomacropeptide). 1When adjusted for entry values, the weight-for-age z score at 6 mo of age was significantly lower (P < 0.05) in the breastfed group than in all of the formula-fed groups. 2When adjusted for entry values, the length-for-age z score at 6 mo of age was significantly higher (P < 0.05) in the standard formula group than in the RGMP group. 3When adjusted for entry values, the head circumference z score at 6 mo of age was significantly higher (P < 0.05) in the standard formula group than in the RGMP and breastfed groups.

Health and sleep patterns
There were no group differences in the number of infections, days with fever, or days with symptoms of upper respiratory infection (Table 3). We did not observe any differences in bowel habits or stool consistency between groups, nor were there any differences in sleep patterns between the formula-fed groups. Total daily sleep time did not differ between groups (Table 4).

Table 5

Table 6

Figure 2A

View larger version (43K): [in this window] [in a new window]   FIGURE 2. Mean (±SD) plasma concentrations of essential amino acids and nonessential amino acids at 4 and 6 mo of age. Groups were compared by using ANOVA and a Bonferroni post hoc test. Values with different superscript letters are significantly different (P < 0.05). -LAC, -lactalbumin enriched (15% glycomacropeptide); RGMP, -lactalbumin enriched (10% glycomacropeptide).

Figure 3

View larger version (48K): [in this window] [in a new window]   FIGURE 3. Mean (±SD) total plasma concentrations of isoleucine, leucine, and valine combined at 4 and 6 mo of age. Groups were compared by using ANOVA and a Bonferroni post hoc test. Values with different superscript letters are significantly different (P < 0.05). -LAC, -lactalbumin enriched (15% glycomacropeptide); RGMP, -lactalbumin enriched (10% glycomacropeptide).

	DISCUSSION

TOP ABSTRACT INTRODUCTION SUBJECTS AND METHODS RESULTS DISCUSSION REFERENCES

There has been considerable discussion regarding the optimal concentration of protein in infant formula and the risks of excessive protein intake. In the present study, all 3 formulas had the same protein concentration (ie, 13 g/L, 1.95 g/100 kcal). In a randomized intervention trial, Räihä et al (21) compared healthy infants who were breastfed or fed 1 of 2 formulas: one with a protein concentration of 12.1 g/L, 1.8 g/100 kcal, and a whey:casein ratio of 70:30 and an increased proportion of -lactalbumin and no GMP and a control formula with 14.7 g protein/L (2.2 g/100 kcal). After 30 d, infant growth patterns did not differ between the 2 formula groups, but concentrations of BUN were lower in infants that were breastfed or fed the formula with 12.1 g protein/L than in infants that were fed the formula with 14.7 g protein/L. At 2 and 4 mo of age, BUN was greater in formula-fed infants than in breastfed infants.

Lien et al (22) studied healthy term infants from birth until 12 wk of age who were fed standard formula with 15.1 g protein/L (2.25 g/100 kcal), of which -lactalbumin accounted for 1.2 g/L (8%) of the total protein or experimental formula with 14.4 g protein/L (2.15 g/100 kcal), of which 2.2 g/L (15%) of the total protein accounted for -lactalbumin. Infants fed the experimental and standard formulas had similar growth patterns and similar serum concentrations of albumin, and the authors concluded that all of the infants were well nourished. However, infants that were fed experimental formula had a lower BUN concentration. The difference in the protein content of the experimental and standard formulas was a modest 0.7 g/L, and there were no breastfed infants in the study to serve as reference.

Räihä et al (21) argued that elevated BUN is indicative of increased waste nitrogen and increased renal solute load and that a reduction in protein concentration would be beneficial. In the studies cited above, BUN was higher in formula-fed infants than in breastfed infants, although breastfed infants were not included in the Lien et al (22) study. In the present study, BUN values were 50% higher in formula-fed than in breastfed infants, whereas they were 35% higher in the study by Räihä et al (21), which is consistent with the slightly higher protein concentration in the experimental formulas we studied. Considered with the fact that infants fed the experimental formulas grew at the same rate as did the breastfed infants, the implication is that it is possible to reduce the total protein content in infant formula, provided that the remaining protein is of high quality.

Given the fact that the mere composition of a formula is not the proper reference but rather the performance of formula-fed infants compared with that of exclusively breastfed infants is, we assessed plasma amino acid patterns in formula-fed and breastfed infants. Formula-fed groups had higher plasma concentrations of all essential amino acids, except tryptophan. The results suggest that it is possible to reduce the protein concentration in the formula to <13 g/L. However, a reduction in the protein concentration will also result in a reduction in plasma tryptophan, the first limiting amino acid. Indeed, at 4 mo of age, infants fed standard formula had significantly lower plasma tryptophan concentrations than did breastfed infants. It should be noted that Räihä et al (21) did not provide the proportion of -lactalbumin in the formula that they used. Furthermore, the investigators used sweet whey, which contains relatively more tryptophan than does conventional acid whey and led to tryptophan concentrations similar to those of breastfed infants.

In the present study, we used an -lactalbumin–enriched protein fraction to increase the tryptophan content of the formula, and the -LAC and RGMP formulas contained 20% more tryptophan than did breast milk and standard formula. Thus, feeding infants with those formulas resulted in plasma tryptophan concentrations that were not significantly different from those of breastfed infants, even though free tryptophan had not been added to the formulas. In contrast, in the study by Räihä et al (21), free tryptophan was added to one of the reduced protein formulas to overcome the potential problem of too-low tryptophan concentrations. However, plasma amino acid concentrations were not reported in that study. Thus, it is not known whether a reduction in protein concentration to <13 g/L results in plasma tryptophan concentrations that are similar to those of breastfed infants. GMP is rich in threonine, and infants fed whey-predominant infant formulas have higher plasma threonine concentrations than do breastfed infants. Therefore, formula with a reduced GMP concentration is likely to decrease the difference between formula-fed and breastfed infants. In fact, this was reported by Rigo et al (23) when they studied the effects of GMP-free formula on preterm infants. However, although one of the present experimental formulas had a reduced GMP content, it did not result in a lower plasma threonine concentration, which may be explained by the too-small difference in threonine content between the formulas. However, the lack of difference suggests that a reduction in the GMP content in formula is not necessary in term infants. Interestingly, it has been suggested that the difference in plasma threonine concentrations between formula-fed and breastfed infants is due to a difference in threonine metabolism (24). This suggestion should be studied further.

There were no significant group differences in hemoglobin and S-Ft. However, S-Fe was significantly higher in the -LAC group than in the breastfed group. Consistent with this finding, iron-binding capacity in the -LAC group was significantly lower than that in the standard formula and RGMP groups. This suggests that iron absorption was greater in the -LAC group than in the other groups. We previously reported that infant rhesus monkeys fed -lactalbumin–enriched formula had greater iron absorption and hematocrit than did monkeys that were fed control formula (25). Although the reason for the greater iron utilization in infants fed -lactalbumin formula is not clear, -lactalbumin is known to bind divalent cations (6), and it is possible that smaller peptides formed during digestion facilitate iron absorption.

In conclusion, modification of the protein composition of infant formula by increasing its proportion of -lactalbumin resulted in growth patterns in infants that were similar to those of breastfed infants, possibly because of a consequent reduction in plasma concentrations of insulinogenic amino acids. Plasma tryptophan concentrations in infants fed -lactalbumin–enhanced formulas were more similar to those of breastfed infants than to those of infants fed standard formula, which suggests that the protein quality of the formula was enhanced. The high plasma concentrations of all other essential amino acids and BUN suggest that it is possible to reduce the protein concentration in formula to <13 g/L, provided that high-quality protein sources are used. Further studies should be conducted to verify the safety of such formulas.

	ACKNOWLEDGMENTS

 
We are grateful to the participating families. We thank Margareta Henriksson and Margareta Bäckman for their invaluable interactions with the infants and their parents and for collecting anthropometric data and blood samples, Yvonne Andersson for her contribution to data compilation, and Hans Stenlund (Department of Epidemiology and Public Health, Umeå University) for statistical assistance.

The authors' responsibilities were as follows—GG: participated in the study design, product composition, and manuscript editing; OH and BL: responsible for the study design and the study protocol and participated in the data analyses and manuscript preparation; and OS: compiled the database, performed most of the data analyses, and primarily responsible for writing the manuscript. GG is an employee of Arla Foods Ingredients, Aarhus, Denmark. None of the other authors declared any conflicts of interest.

	REFERENCES

TOP ABSTRACT INTRODUCTION SUBJECTS AND METHODS RESULTS DISCUSSION REFERENCES

 

1. Jackson J, Janszen D, Lönnerdal B, Lien E, Pramuk K, Kuhlman C. A multinational study of alpha-lactalbumin concentrations in human milk. J Nutr Biochem 2004;15:517–21.[Medline]
2. Chatterton D, Holst HH. A process for preparing a kappa-caseino glycomacropeptide or a derivative thereof. Viby, Denmark: MD Foods AMBA, 1999.
3. Holt C, McPhail D, Nylander T, et al. Apparent chemical composition of nine commercial or semi-commercial whey protein concentrates, isolates and fractions. Int J Food Sci 1999;34:587–601.
4. Heine W, Klein P, Reeds P. The importance of alpha-lactalbumin in infant nutrition. J Nutr Biochem 1991;121:277–83.
5. Lönnerdal B. Nutritional and physiologic significance of human milk proteins. Am J Clin Nutr 2003;77(suppl):1537S–43S.[Medline]
6. Lönnerdal B, Lien EL. Nutritional and physiologic significance of alpha-lactalbumin in infants. Nutr Rev 2003;61:295–305.[Medline]
7. Karlsland Åkeson P, Axelsson IC, Räihä NC. Protein and amino acid metabolism in three- to twelve-month-old infants fed human milk or formulas with varying protein concentrations. J Pediatr Gastroenterol Nutr 1998;26:297–304.[Medline]
8. Schmidt IM, Damgaard IN, Boisen KA, et al. Increased kidney growth in formula-fed versus breast-fed healthy infants. Pediatr Nephrol 2004;19:1137–44.[Medline]
9. Lien E, Davis A, Euler A. Infant formulas with increased concentrations of alpha-lactalbumin. Am J Clin Nutr 2003;77(suppl):1555S–8S.[Medline]
10. Alais C, Jolles P. Etude comparee des caseinoglycopeptides formes par action de la presure sur les caseines de vache, de brebis et de chevre. II. Etude de la partie non-peptidique. [Studies comparing caseinoglycopeptides formed from cow, sheep, and goat milk casein. II. Studies on the non-peptide fraction.] Biochim Biophys Acta 1961;51:315–22 (in French).
11. Bruck W, Graverholt G, Gibson G. A two-stage continuous culture system to study the effect of supplemental alpha-lactalbumin and glycomacropeptide on mixed cultures of human gut bacteria challenged with enteropathogenic Escherichia coli and Salmonella serotype typhimurium. J Appl Microbiol 2003;95:44–53.[Medline]
12. Bruck W, Kelleher S, Gibson GR, Nielsen K, Chatterton D, Lönnerdal B. rRNA probes used to quantify the effects of glycomacropeptide and alpha-lactalbumin supplementation on the predominant groups of intestinal bacteria of infant rhesus monkeys challenged with enteropathogenic Escherichia coli. J Pediatr Gastroenterol 2003;37:273–80.[Medline]
13. Li EW, Mine Y. Immunoenhancing effects of bovine glycomacropeptide and its derivatives on the proliferative response and phagocytic activities of human macrophagelike cells, U937. J Agric Food Chem 2004;52:2704–8.[Medline]
14. Boehm G, Cervantes H, Georgi G, et al. Effect of increasing dietary threonine intakes on amino acid metabolism of the central nervous system and peripheral tissues in growing rats. Pediatr Res 1998;44:900–6.[Medline]
15. Bruck WM, Redgrave M, Tuohy KM, et al. Effects of bovine -lactalbumin and casein glycomacropeptide-enriched infant formulae on faecal microbiota in healthy term infants. J Pediatr Gastroenterol Nutr 2006;43:673–9.[Medline]
16. Koletzko B, Baker S, Cleghorn G, et al. Global standard for the composition of infant formula. Recommendations of an ESPGHAN coordinated International Expert Group. J Pediatr Gastroenterol Nutr 2005;41:584–99.[Medline]
17. Kuczmarski R, Ogden C, Guo S, et al. CDC Growth Charts for the United States: methods and development. Vital Health Stat 2000;11:1–190.
18. Nilsson M, Stenberg M, Frid AH, et al. Glycemia and insulinemia in healthy subjects after lactose equivalent meals of milk and other food proteins: the role of plasma amino acids and incretins. Am J Clin Nutr 2004;80:1246–53.[Abstract/Free Full Text]
19. Savino F, Costamagna M, Prino A, Oggero R, Silvestro L. Leptin levels in breast-fed and formula-fed infants. Acta Paediatr 2002;91:897–902.[Medline]
20. Locke R. Preventing obesity: the breast milk-leptin connection. Acta Paediatr 2002;91:891–4.[Medline]
21. Räihä N, Fazzolari-Nesci A, Cajozzo C, et al. Whey predominant, whey modified infant formula with protein/energy ratio of 1.8 g/100 kcal: adequate and safe for term infants from birth to four months. J Pediatr Gastroenterol Nutr 2002;35:275–81.[Medline]
22. Lien E, Davis A, Euler A. Growth and safety in term infants fed reduced-protein formula with added bovine alpha-lactalbumin. J Pediatr Gastroenterol Nutr 2004;38:170–6.[Medline]
23. Rigo J, Boehm G, Georgi G, et al. An infant formula free of glycomacropeptide prevents hyperthreoninemia in formula-fed preterm infants. J Pediatr Gastroenterol Nutr 2001;32:127–30.[Medline]
24. Darling P, Dunn M, Sarwar G, Brookes S, Ball R, Pencharz P. Threonine kintetics in preterm infants fed their mothers' milk or formula with various ratios of whey to casein. Am J Clin Nutr 1999;69:105–14.[Abstract/Free Full Text]
25. Kelleher S, Chatterton D, Nielsen K, Lönnerdal B. Glycomacropeptide and alpha-lactalbumin supplementation of infant formula affects growth and nutritional status in infant rhesus monkeys. Am J Clin Nutr 2003;77:1261–8.[Abstract/Free Full Text]

This Article Abstract Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Sandström, O. Articles by Hernell, O. Search for Related Content PubMed PubMed Citation Articles by Sandström, O. Articles by Hernell, O. Agricola Articles by Sandström, O. Articles by Hernell, O.