Genetic sensitivity to 6-n-propylthiouracil and sensory responses to sugar and fat mixtures.

This study tested the hypothesis that genetic sensitivity to 6-n-propylthiouracil (PROP) is associated with greater sensitivity to sugar and fat in foods. Subjects were 118 young women from different ethnic backgrounds, mean age 26.9 years and mean body mass index (BMI) 23.4. The women were classified as nontasters (n = 39), medium tasters (n = 48), or supertasters (n = 31) of PROP. Nontasters of PROP had thresholds of 1.8 x 10(-4) mol/L PROP or greater, whereas tasters had thresholds below 1.0 x 10(-4) mol/L PROP. PROP tasters were divided into medium tasters and supertasters, based on the ratio of intensity ratings of suprathreshold PROP solutions relative to NaCl solutions. Supertasters were defined as those with PROP/NaCl ratios of 1.90 or more. The pattern of sensory responses to sweetened dairy products of varying sugar and fat contents closely replicated data obtained in other studies. Genetic sensitivity to PROP was not associated with enhanced perception or altered hedonic response profiles for this range of 15 sugar/fat mixtures. Separating subjects into "likers" and "dislikers" of sweetened dairy products failed to reveal significant links to PROP taster status in this all-female sample.