Effects of Formula Protein Level and Ratio on Infant Growth, Plasma Amino Acids and Serum Trace Elements I. Cow's Milk Formula

Abstract

The optimum level and ratios of protein to be used in cow's milk formula has recently been under discussion. Healthy term infants were fed from birth exclusively human milk or a formula that varied in protein level or whey: casein ratio: (A) 1.4 g/dl; 55:45, (B) 1.5 g/dl; 55:45, (C) 1.3 g/dl; 55:45, (D) 1.4 g/dl; 60:40, (E) 1.4 g/dl; 20:80. Infants were followed for 12 weeks and blood samples were taken at 2, 4, 8 and 12 weeks. Anthropometric indices did not show any significant differences among groups. Plasma amino acid and BUN levels of the C group were closest to the breast-fed group, while the formula with the highest protein level (B) resulted in high values for some amino acids. When comparing the formulas with 1.4 g protein/dl, the high casein group had the lowest plasma tryptophan levels. Taurine was added to all formulas at a level similar to that of breast milk; plasma taurine levels were similar for all groups. All formulas contained 0.7 mg iron and 0.7 mg zinc/dl; no differences were found among the groups in hematological indices or serum trace elements. These data show that feeding a formula with 1.3 g protein/dl and 55:45 whey: casein ratio from birth will result in growth and metabolic indices similar to those of breast-fed infants, although some plasma amino acid levels are not identical, 1990.

Tryptophan Released From Mother's Milk Has Antioxidant Properties

“…Milkbased infant formulae are produced by adding whey protein concentrate to skimmed cow's milk powder to yield a similar whey to casein ratio as that of HM. This modification results in an amino acid composition that is still quite different from that of HM protein, especially in terms of the Trp content (27). Trp is a precursor in the synthesis of the neurotransmitter serotonin, which is involved in the regulation of appetite, circadian rhythm, and affective reaction control (28).…”

The Composition of Human Milk as a Model for the Design of Infant Formulas: Recent Findings and Possible Applications

“…A major reason for this decrease has been the finding that formula fed infants have elevated plasma concentrations of urea and of specific amino acids, which suggests that these infants may be exposed to unnecessary metabolic stress (Jarvenpaa et al 1982a, b ;Janas et al 1985). Several studies evaluated the effects of lowering the protein content of formula to values of 11-13 g/l, while varying the casein:whey protein ratio (Raiha et al 1986a, b ;Lonnerdal & Chen, 1990). Infants receiving such a low protein formula had growth rates and indices of protein nutritional status similar to those of breast fed infants.…”

“…The optimal casein :whey protein ratio of infant formulas is still a point of controversy. Growth rates do not differ between infants fed whey predominant formulas and those receiving casein predominant formulas (Harrison et al 1987;Janas et al 1987;Lonnerdal & Chen, 1990). Theoretically, whey predominant formulas may offer some minor advantages for newborns because they form a finer, softer curd than casein predominant formulas leading to higher gastric emptying rates, which are more comparable to those of breast fed infants (Nakai & Li-Chan, 1987;Billeaud et al 1990).…”

Milk protein intake, the metabolic-endocrine response, and growth in infancy: data from a randomized clinical trial

“…Animal and observational studies in humans, as well as some small controlled trials in infants (2)(3)(4), showed diet, and especially protein intake, to modulate blood concentrations of insulin-like growth factor (IGF)-I (5). The IGF axis is known to regulate early growth and was also shown to influence adipose tissue differentiation and early adipogenesis in animals and in humans (6)(7)(8).…”