supertaster

A supertaster is someone in a group rating the bitter substance 6-n-propylthiouracil (PROP) as extremely bitter. In one taste trial grading response strength to PROP and other oral stimuli, a group emerged that rated PROP especially bitter. This group tended to perceive stronger tastes from bitter and sweet substances and stronger burning from alcohol and capsaicin; women were described as more frequent in the group. This account is based on an abstract and does not establish participant count, scoring methods, or effect sizes.

The word supertaster is described as first appearing in print in a 1991 trade-journal article. In the laboratory behind it, PROP non-tasters were observed to be relatively homogeneous, whereas tasters varied much more and included a subgroup rating PROP intensely bitter. This is a secondary account of the term's origin; the 1991 article itself was not read for this review.

The view that strong bitterness response to PROP signals generally amplified oral sensation is contested. A critical 2011 review argued that heightened responses among people who strongly perceive temperature-induced tastes or report bitter side tastes from irritants are distinct from PROP bitterness and cannot be explained by the genotype associated with PROP bitterness. The authors proposed a separate term, detached from the PROP operational definition, for broadly heightened oral sensation.

In a study of 243 participants rating PROP at 5 concentrations, TAS2R38 genotype explained 29.3% of variance in bitterness ratings at the highest concentration (3.2 mM; F(1,216) = 89.4, p < 0.0001). Independently, TAS2R4 genotype explained an additional 7.7% at that concentration (F(1,206) = 17.20, p < 0.0001). Mean ratings were 18.4 (±3.9) among 26 participants homozygous for low-function forms of both genes and 56.8 (±3.9) among 27 homozygous for high-function forms, an approximately 3.1-fold difference.

In the same study's in vitro experiment, calcium imaging in cells expressing TAS2R4 found 3 mM PROP to be a weak TAS2R4 agonist. This weak response was found only at high concentration, and the authors themselves said its physiological significance requires further testing.