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Early developmental change in bitter taste responses in human infants
H Kajiura1, B J Cowart, G K Beauchamp
1Kirin Brewery Co., Ltd. Tokyo, Japan.
Insights
Newborns show limited rejection of urea, while older infants reject it, indicating a developmental change in bitter taste perception in infants.
Area of Science:
- Human infant development
- Sensory perception
- Gustatory system development
Background:
- Bitter taste perception is crucial for survival, aiding in the avoidance of toxic substances.
- Understanding the development of bitter taste in infants is important for infant nutrition and health.
- Previous research suggests taste preferences and aversions develop early in life.
Purpose of the Study:
- To investigate developmental changes in human infant responses to urea, a bitter substance.
- To compare the bitter taste perception of human newborns (0-6 days) and older infants (14-180 days).
- To assess how different concentrations of urea affect infant intake, sucking behavior, and hedonic responses.
Main Methods:
- Infants were offered urea solutions (0.12-0.24 M) in a sweet diluent and the diluent alone.
- Measures included relative fluid intake, sucking behavior patterns, and hedonic ratings (facial expressions, body movements).
- Responses were analyzed based on infant age groups: newborns and older infants.
Main Results:
- Newborns showed no significant rejection of urea in intake or sucking behavior; responses were influenced by taste presentation order.
- Older infants demonstrated a tendency to reject all tested concentrations of urea.
- Hedonic ratings indicated limited rejection of urea by newborns, but more consistent rejection by older infants.
Conclusions:
- There is a significant developmental shift in the perception and rejection of bitter tastes, like urea, during early infancy.
- Infant bitter taste perception matures, leading to increased aversion to bitter substances as they age.
- These findings have implications for understanding infant dietary acceptance and potential interventions.
Abstract:
Human newborns (birth-6 days) and older infants (14-180 days) were allowed to ingest both urea (0.12-0.24 M) in a mildly sweet diluent and the diluent alone, and multiple measures of responsivity were obtained (relative intake, sucking behavior, and hedonic ratings based on facial expressions and body movements). For newborns, there was no indication of rejection of urea relative to the diluent in measures of intake or sucking behavior; rather, their responses were predominantly controlled by the order of presentation of the two tastes. In contrast, older infants tended to reject all concentrations of urea according to these measures. Hedonic ratings provided an indication of limited rejection of the bitter taste by newborns, but older infants were still found to respond more consistently. These data suggest there is an early developmental change in bitter taste perception.