424 MILK PROTEIN QUALITY AND QUANTITY: EFFECTS ON ORGANIC ACIDS IN LOW BIRTH WEIGHT INFANTS (LBWI)

Abstract

Urinary excretion of organic acids (OA) was determined by gas chromatography-mass spectrometry in 105 LBWI (≥ 2100g) randomly assigned to diets of: pooled human milk (HM) or one of four isocaloric formulas varying in prot. quant. (1.5 or 3.0 g%) or qual. (whey:casein of 18:82 or 60:40). Differences were reported previously for pH, neg. base excess and both plasma and urine amino acid conc. as a function of both qual. and quant. of diet prot. The TYR conc. was most Increased of the amino acids, and its metabolites, p-OH-phenylacetic and p-OH-phenyllactic acids, are the most increased OA's. The OA metabolites of PHE were not increased in the infants fed the 3.0 g% (18:82) formula (F₄) compared to those fed HM; this finding correlated with the lesser effect of this formula on PHE compared with its effect on TYR. α-Keto-γ-methiolbutyrate, the α-keto acid of MET, was also excreted in higher concs. in the infants fed the F₄ formula compared to HM and correlated with similar effects on MET. Other OAs were less affected or not different.

Thus, biochemical effects of different prot. qual. and quant. in formulas are seen in the OAs as well as in the amino acids. These effects give further evidence of the need for caution in the use of formulas for LBWI in which prot. qual. and quan. have not been evaluated systematically. (Supported by the New York State Department of Mental Hygiene.)

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