The experimental research on children that suggests the liking of sweet and bitter tastes reflects children’s basic biology.
Children prefer sweet tastes, which attract them to mother’s milk and even act as an analgesic. They prefer higher sweet levels than do adults, with preferences declining to adult levels during middle to late adolescence, which coincides with the cessation of physical growth. The level of sweetness most preferred by children has remained heightened relative to adults for nearly a decade, despite reductions in sugar, both consumed and in the food environment. Despite these reductions, however, children’s sugar intake remains higher than that recommended by health organizations worldwide. In contrast to sweet taste, children dislike and reject bitter taste, protecting them from ingesting poisons. Although variation in bitter taste receptor genes such as TAS2R38 accounts for people’s marked differences in perceptions of the same bitter-tasting compounds, basic research revealed that these genotype-phenotype relationships are modified with age, with children of the same genotype being more bitter sensitive than adults and the changeover occurring during mid-adolescence. This heightened bitter sensitivity is also evident in the taste of the foods (green vegetables) or medicines (liquid formulations of drugs) they dislike and reject. While bitter taste can be masked or blocked to varying degrees by sugars and salts, their efficacy in modulating bitterness is based not only on the type of bitter ligand but also on the person’s age. Children’s heightened preference for sweet and dislike of bitter, though often detrimental in the modern food environment, reflects their basic biology. Increasing knowledge of individual variation in taste due to both age and genetics will shed light on potential strategies to promote healthier eating since chronic diseases derive in large part from poor food choice dictated by taste preferences as well as to contribute to a new era of drug formulations designed especially for the taste palate of children.
Keywords: children, taste, learning, genetic variation, diet
Sweet ; the taste of pleasure
The sensations experienced when tasting something sweet are mediated by receptors in the periphery and by multiple brain substrates, associated with reward-related learning and behaviors .
Taste receptor cells produce proteins that participate in sweet taste transduction, and some of these proteins are inserted into the cell membrane to form taste receptors. T1R2 and T1R3 (taste receptor family 1, proteins 2 and 3) combine to create a sweet receptor; their associated genes are TAS1R2 and TAS1R3.
Several lines of evidence indicate that the liking for sweet taste is inborn. Before birth, the ability to detect sweet tastes functions and interacts with systems controlling effect and suckling [10]; thus, babies are born able to detect and prefer the predominant taste quality of the food they need to survive: mother’s milk. Newborns respond even to dilute sweet tastes, differentiate varying degrees of sweetness, and, given a choice, consume more of a sugar solution than water [11, 12].
When a sweet solution is placed in the oral cavity, the infant’s face relaxes, resembling an expression of satisfaction that may be followed by a smile.
Perhaps most investigated in the ontogeny of human sweet perception is the ability of sweet tastes to act as an analgesic in infants and children. Small amounts of a sweet solution placed on the tongue of a crying newborn exert a rapid, calming effect that persists for several minutes [18, 19]. Because non-caloric sweet substances such as aspartame mimic the calming effects of sucrose [19],
and because the administration of sucrose by direct stomach loading is not effective [20], it appears that afferent signals from the mouth, rather than metabolic or gastric changes, are responsible for the analgesic properties of sweet tastes. Recent systematic reviews on this body of research concluded that administration of sweet tastes is safe and effective for reducing procedural pain in infants from single painful events such as heel lance, venipuncture, and circumcision in the short term .
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