Human sweet taste reactivity: Determinants of hedonic response

Abstract

<p>This series of experiments explored aspects of sweet taste reactivity in humans, primarily focusing on individual differences which may be relevant for understanding the interactions between taste and food intake. The effect of metabolic state on sweet reactivity depends upon the subjects' underlying hedonic response to sweet (Experiment 1). Subjects can be classified into two major categories: sweet likers (i.e., increased liking with increasing concentration) and sweet dislikers (i.e., decreased liking with increasing concentration). Only the sweet dislikers show an attenuated dislike for concentrated sucrose when deprived; as well, they sip less solution when sated than deprived. Experiment 2 establishes the predictive validity of the hedonic response measures by demonstrating that another known index of hedonic response, facial expressions, can be used to predict sweet liker/disliker status. The sweet liker/disliker distinction correlates strongly with the genetically-determined ability to taste 6-n-propylthiouracil (PROP): PROP nontasters are almost always sweet likers, while sweet dislikers are almost always PROP tasters. This relationship also holds for 7-to-10 year old children, as Experiment 3 shows. Sensory differences may underlie the hedonic differences in taste response, since Sweet dislikers perceive a purer sweet sensation than likers, who report nonsweet (bitter, salty or sour) components in pure sucrose solutions (Experiment 4). The sweet liker/disliker distinction transfers almost perfectly to red, strawberry-flavoured solutions (Experiment 5). However, sweet dislikers show an attenuated dislike for concentrated sweet tastes with the addition of the odour and colour, suggesting that other sensory dimensions of the taste stimulus, such as smell and vision, have an impact on the hedonic value of the taste. These experiments suggest that the sweet liker/disliker distinction reflects an individual difference in taste reactivity which should be accounted for in future explorations of other gustatory encoding, and of the role of taste in eating. Further studies should explore the generality of the sweet liker/disliker distinction to other gustatory stimuli, its predictive value for "real food" preferences and intake, and identify the specific sensory differences which underlie these hedonic response patterns.</p>