Free Amino Acid Concentrations of Human and Cow's Milk and Effect of Taurine Supplementation to Infant Milk Formulas on Serum Taurine Levels of Infants

Abstract

Taurine and other free amino acids were determined in human and cow's milk at different days of lactation. Taurine concentrations in human milk were high next to glutamic acid and taurine percent of total free amino acids was almost constant during lactation. Taurine concentrations in cow's milk of 3 days lactation were similar to those in human colostrum, but pooled cow's milk from which infant formulas are prepared was considerably lower than those of human mature milk. Characteristic patterns of other free amino acids were observed with days of lactation. Especially high proline in human milk and high glycine in cow's milk were marked at the stage of colostrum. These differences may reflect the phenamena of protein synthesis in the mammary gland. Ethanolamine, phosphoethanolamine and phosphoserine which are ninhydrin-positive compound related to phospholipid were observed in the milk of both man and cow. The response af serum taurine concentrations to feeding one of formulas with and without taurine suppl mentation or human milk was measured in the term and premature infants. The premature infants appear to be more susceptible to taurine deficient formulas than does the term infant. Supplementation of formula with amounts of taurine comparable to those present in human milk will maintain nearly the same serum taurine concentrations as human milk does.