INFANT SALT TASTE - DEVELOPMENTAL, METHODOLOGICAL, AND CONTEXTUAL FACTORS

Two studies investigated the human infant's response to salt during development. In the first study, measures of intake and sucking were obtained from two groups of infants, newborns and 4- to 8-month-olds, in response to brief presentations of two concentrations of salt (0.2 or 0.4 M) and water. For several measures of sucking and for intake, there were significant age and concentration effects. Generally, newborn infants tended to reject saline relative to water more than did 4- to 8-month-old infants. This result, consistent with previously published research, suggests a developmental change in salt acceptability and, probably, sensitivity in the human infant. In the second longitudinal study, the response to salted (0.15 M) versus unsalted formulas was evaluated monthly in infants 2 to 7 months of age. Again, a developmental change was observed: Based on some sucking measures, younger infants appeared to be indifferent to the salted formula relative to the unsalted formula whereas older infants tended to reject the salted formula, presumably because either it was less sweet than the unsalted formulas or because it was novel. These data are consistent with the hypothesis developed from animal model studies that during early human postnatal development, transductive elements sensitive to saltiness mature. (C) 1991 John Wiley and Sons, Inc.