BALANCE OF NET ACID IN GROWING INFANTS

Abstract

Summary: A method for the quantitative assessment of the balance of net acid (NAB) in growing infants with a changing body composition is described. Results of seventy measurements of the daily NAB in healthy growing premature infants ingesting modified cow's milk formulae are reported. The relative contributions of the various determinants of the daily net acid input in the infant differ from those in the normal adult, and growth appears to be associated with negative net acid balances due to base deposition in skeleton and new body water. The daily load of “undetermined anion” (UA) in the diet was found to be the largest single component of the NAB. Moreover, a strong correlation between the rates of dietary UA intake and fecal UA excretion suggested an active regulation of the transintestinal acid‐base balance. A model for such regulation, based upon available evidence concerning the transport of acid and base across the gastrointestinal membrane, is proposed and briefly discussed.