PROP sensitivity is associated with haplotypes (PAV and AVI) of the receptor gene (TAS2R38), and may be correlated with gene polymorphisms of the gustin (CA6, Zn dependent), and BMI. We investigated the associations between PROP taste sensitivity, TAS2R38 and gustin gene polymorphisms, salivary Zn2+, and BMI.

BMI and salivary Zn2+ were determined in 76 volunteers. PROP sensitivity was determined by scaling and threshold measurements. The molecular analysis of TAS2R38 and gustin DNA were performed using PCR techniques.

BMI and Zn2+ were higher in nontasters than in supertasters. The lowest responsiveness in nontasters is strongly associated to AVI nontasting variant, while the highest responsiveness in supertasters is strongly associated to allele A of gustin gene. Moreover, the allele A is relevant to perceive low concentration, while the PAV variant receptor is more important for tasting high concentrations. The combination of two genes accounts for up to 60% of phenotypic variance in PROP bitterness and to 40% in threshold values.

These data show that PROP sensitivity is inversely related to BMI and salivary Zn2+ and directly associated with a gustin gene dimorphism that is hypothesized to affect gustin function. These novel insights explain how TAS2R38 and gustin gene modulate PROP phenotype providing an additional tool for the evaluation of eating behaviour and nutritional status.