Development of brief methods to classify individuals by PROP taster status

The purpose of this study was to develop brief methods for classifying individuals by genetic taste sensitivity to 6-n-propylthiouracil (PROP). Two methods are described, which are modifications of a commonly used, suprathreshold procedure. Eighty-nine adult subjects rated the perceived intensity of solutions of 0.032, 0.32 and 3.2 mmol/l PROP and 0.01, 0.1, 1.0 mol/l sodium chloride (NaCl) (three-solution test), as well as solutions of 0.32 mmol/l PROP and 0.1 mol/l NaCl (one-solution test) using the Labeled Magnitude Scale (LMS). Subjects were classified as PROP nontasters (n = 22), medium tasters (n = 51) or supertasters (n = 16) by the three-solution test. Taster status was independently determined by the one-solution test using numerical cutoff scores, which were determined by calculating the ±95% confidence interval around the group means for PROP taste intensity. Supertasters gave PROP a rating of ≥51 ("very strong" on the LMS) and nontasters gave PROP a rating of ≤15.5 (approximately "moderate" on the LMS). Medium tasters fell between these two limits. Ninety-one percent of nontasters, 82% of medium tasters and 89% of supertasters were classified in a similar way by the two methods. Agreement between methods was high [coefficient of association (P) = 0.74; P ≤.001]. These data suggest that three- and one-solution methods can reliably classify subjects by taste sensitivity to PROP and could provide valuable tools in population-based studies.