Salivary Interactions With Chemosensations

May 23, 2023 updated by: Cordelia Running, PhD, Purdue University
A counterbalanced, crossover design will be used to evaluate whether exposure to flavors vs. a control over time alters the perception of the flavor by changing an individual's salivary protein profile. Participants will complete 3 acute tasting protocols (baseline, after intervention 1, after intervention 2). The interventions will be with the flavor (epigallocatechin gallate, linolenic acid, capsaicin) or a control, in counterbalanced order, and will involve swishing and swallowing a solution of that sample 5 times per day for two weeks. Each of these flavors will be a separate sub-study.

Study Overview

Status

Terminated

Conditions

Intervention / Treatment

Detailed Description

This study is designed to test the relationship between salivary proteins, flavor sensation, and flavor exposure. For this study, we will test the bitterness/astringency of epigallocatechin gallate (EGCG, a polyphenol), the oleogustus (fatty acid taste) of linolenic acid, and the spiciness of capsaicin in conjunction with the concentration of specific salivary proteins (initially: salivary proline rich proteins for EGCG intervention, lipocalin-1 for the other two, but other proteins may be identified in the post-hoc analysis of the salivary proteome). We will test whether higher expression of these specific salivary proteins correlates with lower intensity of these flavors. We will further attempt to confirm the role of these salivary proteins using food-sourced functional analogs for these proteins. We would expect the food-sourced protein to have the same effect on flavor as the salivary protein if our hypotheses about salivary proteins' influence on flavor are correct. Finally, we will also use denatured versions of the food-sourced proteins to again confirm that effects are due to the function of these proteins binding the flavor.

Additionally, we will repeatedly expose individuals to the flavors by having them rinse and swallow solutions of the flavor compounds multiple times per day for two weeks. We will then re-evaluate the sensory ratings and salivary protein profiles. Two weeks of rinsing and swallowing a control solution will be used as a control during this intervention (for each of the flavors of interest).

To collect saliva and establish bitterness/astringency perception, we will use an acute tasting protocol. Participants will rinse with water, then taste and swallow, then taste and expectorate a solution of the flavor of interest. Saliva will be frozen for later proteomic analysis. Next participants will taste solutions of: flavor, flavor with food analog, the flavor with denatured food analog, water, water with the food analog, and water with denatured food analog. The participants will rank these solutions in order from least intense to most intense for the flavor quality of interest (bitterness/astringency for EGCG). After this, participants will taste all 6 samples again, and rate each individually for the intensity of the bitterness/astringency. After a short wait, this tasting and intensity rating will be repeated. All tastings will be done in counterbalanced order, and solutions will be labeled with randomized 3-digit codes.

This acute tasting protocol will be done: at baseline, after 2 weeks on one intervention (repeated tasting of flavor or control), after 2 weeks on the other intervention.

Study Type

Interventional

Enrollment (Actual)

32

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Indiana
      • West Lafayette, Indiana, United States, 47907
        • Purdue University

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 45 years (Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Agree to maintain current diet throughout intervention
  • Agree to inform us if medication use changes during study.
  • Willing and able to taste and consume samples, as well as take pictures to document use of the flavor during intervention.

Exclusion Criteria:

  • Known issues with salivation, taste, or smell
  • Taking medications other than birth control
  • User of tobacco products or electronic cigarettes within the last 30 days

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Epigallocatechin gallate
Epigallocatechin gallate solutions will be provided to participants to rinse with daily for two weeks. A control solution will be provided for two weeks as well. Order will be counterbalanced across participants and groups.
Other: Epigallocatechin gallate
Colored solution prepared with epigallocatechin gallate to be consumed daily for two weeks during the epigallocatechin gallate intervention.
Other: Epigallocatechin gallate control
Colored control solution to be consumed daily for two weeks during the epigallocatechin gallate intervention.
Experimental: Linoleic acid
Linoleic acid emulsion will be provided to participants to rinse with daily for two weeks. A control solution will be provided for two weeks as well. Order will be counterbalanced across participants and groups.
Other: Linoleic acid
Colored emulsion prepared with linoleic acid to be consumed daily for two weeks during the linoleic acid intervention.
Other: Linoleic acid control
Colored control solution to be consumed daily for two weeks during the linoleic acid intervention.
Experimental: Capsaicin
Capsaicin solutions will be provided to participants to rinse with daily for two weeks. A control solution will be provided for two weeks as well. Order will be counterbalanced across participants and groups.
Other: Capsaicin solution
Colored solution prepared with capsaicin to be consumed daily for two weeks during the capsaicin intervention.
Other: Capsaicin control
Colored control solution to be consumed daily for two weeks during the capsaicin intervention.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Salivary proteins
Time Frame: 9 months per sub-study (intervention type)
Subjects saliva will be collected at baseline, after the flavor intervention, and after control intervention (two weeks each, order counterbalanced) for each type of intervention (epigallocatechin gallate, linoleic acid, capsaicin). The proteomic composition of the saliva samples will be established, and used to evaluate relationships with other outcome measures.
9 months per sub-study (intervention type)
Flavor intensity ratings
Time Frame: 9 months per sub-study (intervention type)
Flavor intensities for the flavor of interest (bitterness/astringency, oleogustus, and spiciness) will be collected at baseline, after the flavor intervention, and after control intervention (two weeks each, order counterbalanced) for each type of intervention (epigallocatechin gallate, linoleic acid, capsaicin). Subjects will rate (in duplicate) the intensity of flavor from the following solutions: flavor in water, flavor in water with food-sourced salivary protein analog, flavor in water with denatured food-sourced salivary protein analog, water, water with food-sourced salivary protein analog , water with denatured food-sourced salivary protein analog. These ratings will be evaluated in context of the timeline of the exposure as well as the salivary proteome.
9 months per sub-study (intervention type)
Flavor rankings
Time Frame: 9 months per sub-study (intervention type)
Flavor rankings for the flavor of interest (bitterness/astringency, oleogustus, and spiciness) will be collected at baseline, after the flavor intervention, and after control intervention (two weeks each, order counterbalanced) for each type of intervention (epigallocatechin gallate, linoleic acid, capsaicin). Subjects will rank the following solutions from most to least intense: Flavor in water, flavor in water with food-sourced salivary protein analog, flavor in water with denatured food-sourced salivary protein analog, water, water with food-sourced salivary protein analog , water with denatured food-sourced salivary protein analog. These ranking data will be used an another method to gather information on what solutions are most intense to the subject, as the intensity ratings may have complications due to order effects during tastings. These rankings will also be evaluated in context of the timeline of the exposure as well as the salivary proteome.
9 months per sub-study (intervention type)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Purdue University

Collaborators

National Institutes of Health (NIH)

Investigators

  • Principal Investigator: Cordelia Running, PhD, Purdue University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 5, 2019

Primary Completion (Actual)

September 24, 2019

Study Completion (Actual)

December 1, 2021

Study Registration Dates

First Submitted

March 18, 2019

First Submitted That Met QC Criteria

March 18, 2019

First Posted (Actual)

March 21, 2019

Study Record Updates

Last Update Posted (Actual)

May 25, 2023

Last Update Submitted That Met QC Criteria

May 23, 2023

Last Verified

May 1, 2023

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 082-011

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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