Healthy
Conditions
Keywords
bitter taste, psychophysics, genetics, epigenetics, bitterness sensitivity
Brief summary
This single-site, within-subject, experimental study is designed to test the hypothesis that individuals express taste receptors differently and have different sensitivities to bitter taste samples, which results from uneven expression. Subjects will include 100 racially and ethnically diverse, healthy adults. All subjects will provide saliva samples for genetic analysis and undergo taste testing with common psychophysical stimuli. From the pool of 100 subjects, 36 subjects from the common heterozygous group (PAV/AVI) and two from each homozygous group (AVI/AVI, nontaster and PAV/PAV, taster) will be invited to return for two additional sessions. During both sessions the investigators will 1) measure bitterness thresholds for PROP, a common psychophysical stimulus; 2) measure bitterness perception of several vegetables; 3) obtain a saliva sample and 4) collect taste papillae. The investigators will then isolate DNA and RNA from the taste papillae and isolate DNA from saliva to evaluate molecular differences over time and between individuals and how it relates to taste psychophysics. All psychophysical and cellular measurements will be done during both sessions so that the investigators can determine how much variation is observed over a one-week time period in both cellular phenotype and psychophysical phenotype.
Interventions
None listed
Sponsors
National Institute on Deafness and Other Communication Disorders (NIDCD)
Monell Chemical Senses Center
Study design
Observational model
CASE_ONLY
Time perspective
CROSS_SECTIONAL
Eligibility
Sex/Gender
ALL
Age
18 Years to 40 Years
Healthy volunteers
Yes
Inclusion criteria
* Key inclusion criteria include age 18-40 years; English speaking, and good health at the time of study participation.
Exclusion criteria
* Key
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| TAS2R Genotype | 1 day of testing (1-1.5 hours) | Genotype of several TAS2Rs will be determined from DNA extracted from a saliva sample. |
| Taste intensity and hedonic ratings of vegetables | 3 days of testing (1-2 hours each) | Subjects will rate the intensity of five basic taste qualities (bitter, salt, sweet, sour, umami) and the liking of PROP, urea, quinine, caffeine, denatonium solutions and pureed vegetables using the general labelled magnitude scale (gLMS) |
| Bitter taste thresholds | 2 days of testing (2 hours each) | Thresholds for propylthiouracil (PROP) will be measured using modified Harris-Kalmus recognition thresholds. |
| mRNA expression levels | 2 days of testing (2 hours each) | Expression of taste and related genes will be determined from mRNA extracted from human taste tissue obtained via tongue biopsy. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Dietary habits | 2 days (2 hours each) | Subjects will complete a 24 hour diet recall on 2 days of testing. |
| biometrics | 1 day (1-1.5 hours) | Height, weight, blood pressure and bioimpedance measurements will be taken. |
Countries
United States
Outcome results
None listed