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Infant salt taste: developmental, methodological, and contextual factors
G K Beauchamp1, B J Cowart, J A Mennella
1Monell Chemical Senses Center, Philadelphia, PA 19104.
Insights
Human infants show developmental changes in salt preference. Newborns reject salt water more than older infants, who also reject salted formula, indicating maturing salt sensitivity.
Area of Science:
- Developmental Psychology
- Human Infant Nutrition
- Sensory Science
Background:
- Human infants' responses to taste stimuli, including salt, are crucial for understanding early development.
- Previous research suggests a developmental trajectory in salt acceptability, but detailed investigation is ongoing.
Purpose of the Study:
- To investigate the developmental changes in human infants' responses to salt.
- To examine salt acceptability and sensitivity across different infant age groups.
Main Methods:
- Two studies were conducted: one comparing newborns and 4- to 8-month-olds using salt solutions and water, and a longitudinal study of infants aged 2-7 months exposed to salted vs. unsalted formulas.
- Measures included infant intake and sucking patterns in response to varying salt concentrations and formula types.
Main Results:
- Newborn infants demonstrated a greater rejection of saline solutions compared to water than 4- to 8-month-old infants.
- Younger infants (2-7 months) showed indifference to salted formula, while older infants tended to reject it, suggesting a developmental shift in salt perception.
Conclusions:
- Human infants exhibit a developmental change in salt acceptability and sensitivity during early postnatal development.
- Findings support the hypothesis of maturing salt-sensitive transductive elements in early human development.
Abstract:
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.