Threonine kinetics in preterm infants fed their mothers' milk or formula with various ratios of whey to casein
| Autor: | Paul B. Pencharz, Michael Dunn, Ronald O. Ball, Pauline B. Darling, Gulam Sarwar, Steve Brookes |
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| Rok vydání: | 1999 |
| Předmět: |
Threonine
Whey protein Nitrogen balance Administration Oral Biological Availability Medicine (miscellaneous) Gestational Age Breast milk Excretion Animal science Casein Birth Weight Humans Medicine Amino Acids Nutrition and Dietetics Milk Human business.industry Infant Newborn Caseins Gestational age Milk Proteins Whey Proteins Biochemistry Infant formula Infant Food business Oxidation-Reduction Infant Premature |
| Zdroj: | The American Journal of Clinical Nutrition. 69:105-114 |
| ISSN: | 0002-9165 |
| DOI: | 10.1093/ajcn/69.1.105 |
| Popis: | BACKGROUND Plasma threonine concentrations are elevated in infants fed formula containing a whey-to-casein protein ratio of 60:40 compared with concentrations in infants fed formula containing a ratio of 20:80 or human milk (60:40). OBJECTIVE We studied whether degradation of excess threonine was lower in formula-fed infants than in infants fed their mothers' milk. DESIGN Threonine kinetics were examined in 17 preterm infants (gestational age: 31+/-2 wk: birth weight: 1720+/-330 g) by using an 18-h oral infusion of [1-13C]threonine at a postnatal age of 21+/-11 d and weight of 1971+/-270 g. Five infants received breast milk. Formula-fed infants (n = 12) were randomly assigned to receive 1 of 3 formulas (5.3 g protein/MJ) that differed only in the whey-to-casein ratio (20:80, 40:60, and 60:40). RESULTS Threonine intake increased significantly in formula-fed infants with increasing whey content of the formula (48.5, 56.4, and 63.2 micromol.kg(-1).h(-1), respectively; pooled SD: 2.2; P = 0.0001), as did plasma threonine concentrations (228, 344, and 419 micromol/L, respectively; pooled SD: 75; P = 0.03). Despite a generous threonine intake by infants fed breast milk (58.0+/-16.0 micromol.kg(-1).h(-1), plasma threonine concentrations remained low (208+/-41 micromol/L). Fecal threonine excretion and net threonine tissue gain, estimated by nitrogen balance, did not differ significantly among groups. Threonine oxidation did not differ significantly among formula-fed infants but was significantly lower in formula-fed infants fed than in infants fed breast milk (17.1% compared with 24.3% of threonine intake, respectively). CONCLUSION Formula-fed infants have a lower capacity to oxidize threonine than do infants fed breast milk. |
| Databáze: | OpenAIRE |
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