Protein intake and metabolism in formula-fed infants given Swedish or Italian weaning foods.

The aim of the study was to compare protein intake and metabolism between infants from two countries given similar infant formulae but different weaning foods. Healthy Swedish and Italian infants were studied between 3 and 12 mo. Infants in both populations were assigned to 1 of 3 infant formulae, containing 13, 15 or 18/20 g l(-1) of protein, given in addition to Swedish or Italian weaning foods. Protein intake from weaning foods was higher in Italian than in Swedish infants at 6 and 12 mo, whereas protein intake from formula at 6 mo and from formula/milk at 12 mo was similar in both populations. Plasma isoleucine, leucine, lysine, histidine and valine at 6 mo were lower in Italian than in Swedish infants fed formula with 13 g l(-1) of protein. All essential plasma amino acids were similar in Italian and Swedish groups at 12 mo. Serum urea was similar at 6 mo in corresponding formula groups, but was higher at 12 mo in the Italian than in the Swedish formula group. Serum albumin and growth were normal in both populations throughout infancy. In conclusion, formula with protein content of 13 g l(-1) seems to provide sufficient protein intake when combined with Swedish or Italian weaning foods during the second half of infancy, as indicated by normal serum albumin and normal growth. However, the bioavailability of protein and amino acids from weaning foods, in addition to their protein content, should be considered, as indicated by some indices of protein metabolism in the Italian infants.

Ultrasound measurements of subcutaneous adipose tissue in infants are reproducible.

BACKGROUND: The purpose of this study was to evaluate the ultrasound technique for measuring subcutaneous adipose tissue in infants. METHODS: Twenty infants were investigated at 3, 6, and 12 months of age. All measurements were made by the same investigator in triplicate on the left side of the body at the triceps and subscapular anatomic landmarks and at the abdomen and thigh. An ultrasound system equipped with a linear 7.0-MHz transducer was used. RESULTS: The intraclass correlation coefficients were 0.88 to 0.99. Random errors ranged from 0.01 to 0.19 mm. For log-transformed values, the random error ranged from 2.4% to 5.7%. CONCLUSIONS: Measurements of subcutaneous fat in infants using ultrasound are reproducible when performed by the same observer.

Protein and amino acid metabolism in three- to twelve-month-old infants fed human milk or formulas with varying protein concentrations.

BACKGROUND: The metabolic response to different protein intakes from breast milk and/or formulas varying in protein concentrations, in combination with supplementary foods, has not been studied in infants who are in the second half of infancy. METHODS: Healthy infants, exclusively breast-fed until 3 months old, were randomly assigned to one of three groups, F13, F15, or F18, and were given formulas with 13, 15, or 18 g/l of protein, respectively. Infants breast-fed (B) and mixed-fed (M) (breast milk and formula) at 6 months formed the fourth and fifth groups. All infants received the same supplementary foods and were studied from ages 3 to 12 months. RESULTS: The concentrations of albumin, prealbumin, and transferrin were similar in all groups. At 6 months, serum and urine urea concentrations were lower in B and M, compared with urea levels in the formula-fed groups of infants. At 12 months, urine urea was lower in B + M than it was in F18. At 6 months, plasma concentrations of phenylalanine, tyrosine, and methionine were higher in all formula-fed groups; and those of valine. isoleucine, and threonine were higher in F18 and F15 than they were in B and M. Plasma concentrations of methionine, valine, and threonine were higher in F18 than in F13. At 12 months, plasma levels of tyrosine, methionine, valine, isoleucine, and leucine were higher in F18 than they were in B + M. CONCLUSION: Many indexes of protein metabolism were similar in groups F13, B, and M, particularly at 6 months. In contrast, the provision of a formula with 18 g/l of protein resulted in a different metabolic pattern, which could indicate unnecessarily high protein intakes.