NUTRITIONAL-EVALUATION OF PROTEIN HYDROLYSATE FORMULAS

Growth parameters, biochemical indice of protein metabolism and plasma Amino acid (AA) concentrations were investigated during the first mon th of life in term infants (n = 61) fed various protein hydrolysate fo rmulas (whey (WHF, n = 3), soy collagen (SCHF, n = 1) and whey-casein hydrolysate formulas (WCHF, n = 1)). In addition, metabolic balance st udies were performed in 10 infants fed WHF and in 5 fed WCHF. Comparat ively to breast fed infants, growth reduction and decrease in plasma p rotein concentrations were observed with the use of one of the WHF and in a lesser extent with the SCHF and the WCHF. Plasma amino acid patt ern reflected the AA content of the formulas. Whey hydrolysate formula s induced mainly an increase in threonine and a decrease in tyrosine c oncentrations. Soy-collagen hydrolysate formula led to an increase of non-essential amino acids, such as glycine and hydroxyproline and a de crease in plasma lysine and cystine. Whey-casein hydrolysate formula i nduced a plasma amino acid pattern close to the profile observed in br east fed infant. Metabolic balance studies showed a relative reduction in nitrogen absorption and utilisation in the infants fed the WHF and the WCHF. In addition a drastic reduction in fat, calcium and phospho rus absorption was also observed with the use of the WCHF. In preterm infants (n = 19) fed whey predominant hydrolysed preterm formulas (n = 3), metabolic balance studies and plasma AA concentration were evalua ted at the end of the first month of life at 34 weeks of gestational a ge. Comparatively to similar preterm infants fed conventional preterm formulas, a relative reduction in nitrogen absorption (83% vs 90%) and retention (64 vs 70%) as well as in phosphorus absorption (78 vs 89%) was observed. Calcium retention was similar (48 vs 45 mg/kg/d) but ca lcium intake was significantly higher in infants fed hydrolysate formu las 120 vs 91 mg/kg/d. Plasma amino acid concentrations were related t o amino acid composition of the formulas. Compared with the standard p reterm formulas, all three protein hydrolysate formulas led to a signi ficant increase in plasma threonine and a decrease in tyrosine and phe nylalanine concentrations. In addition, there was a reduction in plasm a histidine, valine, leucine, cystine, methionine and/or tryptophane w ith some of the hydrolysate formulas used. In conclusion, these studie s provide evidence that protein hydrolysed formulas are not equivalent to whole protein formulas in terms of nutritional efficiency for pret erm and term infants. Therefore further extensive nutritional studies on growth, biochemical indices of protein metabolism and metabolic bal ance, including minerals and trace elements, appear to be necessary be fore maintaining and promoting the use of such formulas for the potent ial benefits on atopic disease in preterm and in full-term newborn inf ants.