Crowdsourcing taste research: genetic and phenotypic predictors of bitter taste perception as a model

Abstract

Understanding the influence of taste perception on food choice has captured the interest of academics, industry, and the general public, the latter as evidenced by the extent of popular media coverage and use of the term supertaster. Supertasters are highly sensitive to the bitter tastant propylthiouracil (PROP) and its chemical relative phenylthiocarbamide. The well-researched differences in taste sensitivity to these bitter chemicals are partially controlled by variation in the TAS2R38 gene; however, this variation alone does not explain the supertaster phenomenon. It has been suggested that density of papillae, which house taste buds, may explain supertasting. To address the unresolved role of papillae, we used crowdsourcing in the museum-based Genetics of Taste Lab. This community lab is uniquely situated to attract both a large population of human subjects and host a team of citizen scientists to research population-based questions about human genetics, taste, and health. Using this model, we find that PROP bitterness is not in any way predicted by papillae density. This result holds within the whole sample, when divided into major diplotypes, and when correcting for age, sex, and genotype. Furthermore, it holds when dividing participants into oft-used taster status groups. These data argue against the use of papillae density in predicting taste sensitivity and caution against imprecise use of the term supertaster. Furthermore, it supports a growing volume of evidence that sets the stage for hypergeusia, a reconceptualization of heightened oral sensitivity that is not based solely on PROP or papillae density. Finally, our model demonstrates how community-based research can serve as a unique venue for both study participation and citizen science that makes scientific research accessible and relevant to people’s everyday lives.

Denver Papillae Protocol for Objective Analysis of Fungiform Papillae

“…Although many studies corroborated the original claim that FP density is a factor in PROP sensitivities 4,6,12,13 , there has been a small, but important contingency that has found evidence to refute it, reporting an inability to replicate the role 10,14,15,16 . Delwiche et al (2001) warned that the trend is highly variable; FP density does not uniformly account for differences in bitterness sensitivity across subjects, and was only demonstrable for subjects with at least a moderate sensitivity to PROP 7 .…”

“…The FP score data set was then used in the mixed model to assess the combined differences due to protocol (Figure 6), within-scorer variability and the interaction between the two. This model showed a significant difference in scoring when using the Miller & Reedy method compared to DPP (p-value <1 x 10 -6 ) with DPP leading to a higher count by 6.99 (SE = 0.99); 5.2% of the variability in the score was due to training, 25.9% due to scorer, and the remaining due to variability specific to the image 10 . Next, to generate data to determine within-scorer variability, a series of thirty images in random order were scored by 11 individuals.…”

“…The images scored in this study were collected as part of a larger taste study conducted in the Genetics of Taste Lab at the Denver Museum of Nature & Science (the Museum) 10 . Subjects of the larger study were museum visitors (n = 1195) ranging in age from 18-93.…”

“…On copy A, click the candidate to mark as too blue and not a FP. Statistical reliability of DPP was previously studied using a mixed linear model to assess variability 10 . Briefly, to generate data to assess the role DPP plays in consistency of scores, fifteen images were scored twice.…”

Effect of ageing process on fungiform papillae density

“…In the past, it was suggested that higher density of FP may explain biological background of PROP super-tasting ability (Shahbake et al, 2005). However, the newest evaluating models revealed that predictors of taste sensitivity to PROP are age, sex, and haplotype rather than FP density (Garneau et al, 2014).…”