Re-evaluating how sweet-liking and PROP-tasting are related

Past research has identified distinct phenotypic differences in responses to sweet taste, although the origins of these differences remain unclear. One possibility is that these individual differences in sweet-liking are a manifestation of the more widely known differences in sensitivity to the bitter tastant 6-n-propylthiouracil (PROP), which has been related to wider differences in food liking and preference. However, previous studies exploring the relationship between sweet-liking and PROP-tasting have had mixed outcomes. This is possibly due to older studies using a more simplistic dichotic characterisation of sweet likers, whereas recent research suggests three sweet-liking phenotypes (extreme sweet likers, ESL; moderate sweet likers, MSL; and sweet dislikers, SD). To re-assess how sweet-liking and PROP tasting are inter-related, 236 volunteers evaluated their liking for 1.0 M sucrose and the intensity of three concentrations of each NaCl and PROP. Using three different methods for classifying PROP taster status, our analysis confirmed that all three sweet-liking phenotypes were represented in all three PROP taster groups (super-tasters, ST; medium tasters, MT; and non-tasters, NT), but relatively few ESL were classified as ST, or SD as NT. Overall, these data suggest that while PROP tasting and sweet-liking are not causally related, the SD phenotype may partly be explained by a broader tendency for anhedonia.