Plasma Amino Acid Concentrations in Healthy, Full-Term Infants Fed Hydrolysate Infant Formula

Abstract

The effect of feeding hydrolysate infant formula (HF) on protein and amino acid metabolism was investigated in healthy, full-term infants who were either breast-fed (BF, n = 10) or received conventional formula (CF, n = 10) or HF based on soy and beef collagen (n = 10) with equal total protein equivalent contents. There were no differences between groups for gain in weight, length, and head and chest circumferences throughout the study. Plasma concentrations of total proteins, albumin, urea nitrogen, uric acid, and creatinine as well as total amino acid and total essential amino acid concentrations did not differ at the ages of 2, 4, and 8 weeks. In contrast, significant differences were seen in concentrations of five free amino acids. Arginine concentrations were significantly higher at the age of 4 weeks in the infants fed HF than in the other groups (71 +/- 12 versus 27 +/- 6 and 30 +/- 4, mumol/L, mean +/- SEM, HF versus BF and CF, p < 0.01). Plasma histidine concentrations were also higher in infants receiving HF (4 weeks: 217 +/- 33 versus 91 +/- 18, HF versus BF, p < 0.01; 8 weeks: 218 +/- 33 versus 105 +/- 20, HF versus CF, p < 0.01). The most pronounced feeding-related differences were seen in plasma glycine concentrations (2 weeks: 653 +/- 89 versus 345 +/- 55, HF versus BF, p < 0.01; 8 weeks: 613 +/- 74 versus 385 +/- 56 and 312 +/- 46, HF versus BF and CF, p < 0.01), with the mean value exceeding the upper limit of the normal range in infants fed HF. Although the biological importance of the differences observed remains to be clarified, further investigations on amino acid metabolism are needed to establish the final nutritional safety of feeding hydrolysate infant formulae.

Differential Growth Patterns Among Healthy Infants Fed Protein Hydrolysate or Cow-Milk Formulas

“…56 We caution, however, that several studies have documented that infants who were fed PHF have significantly higher serum free amino acids compared with infants fed breast milk or CMF. [57][58][59][60] The consequence of the higher serum amino acids is still unclear, but they may signal an inefficient use of nutrients, which also could have contributed to the slower growth rates among PHF-fed infants. Furthermore, it is unclear whether there are components in CMF that contribute to overfeeding by infants.…”

Effects of Dietary Long-Chain Polyunsaturated Fatty Acids on Plasma Amino Acids and Indices of Protein Metabolism in Infants: Results from a Randomized Clinical Trial

“…At the age of 5 days and 1, 2, 3 and 4 months, venous blood samples were obtained prior to feeding from all participating infants. Plasma total protein, albumin, urea nitrogen and creatinine concentrations were determined immediately as described previously [15]. Blood samples for fatty acid and amino acid analyses were collected into tubes containing ethylenediaminetetraacetate and heparin, respectively, and stored at -20°C until analysis.…”

Protein Digestion of Baby Foods: Study Approaches and Implications for Infant Health

“…Hospitalization may affect infants’ digestion, even though the reason of hospitalization is not related to digestive system. Anthropometric measurements can be taken on infants, such as whole body protein synthesis and breakdown, metabolic and energy balance, and sometimes blood tests [103, 104]. Besides input and output measures, the process of protein digestion has been explored by analyzing contents from infant gastrointestinal tract, which were collected through nasogastric and transintestinal tubes [59, 105–107].…”