Condition category
Not Applicable
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting
Publication status

Plain English Summary

Background and study aims
The fifth sense of taste, the savoury taste known as umami, has been thought to have evolved as a way of signalling the potential presence of protein in foods. One of the chemicals that generates the umami taste is monosodium glutamate (MSG), which occurs naturally in many foods, but the umami taste is further enhanced by the presence of other compounds including inosine monophosphate (IMP). It is well established that protein suppresses appetite more effectively than do carbohydrate or fat, and recent studies suggest that the presence of MSG may be partly responsible for the effects of protein on appetite. No study has looked at the effects of a combination of MSG and IMP and this study sets out to test this since new ways of making foods more filling may be helpful in the future treatment of overeating.

Who can participate?
Healthy volunteers aged 18-40.

What does the study involve?
Volunteers will come to the test centre on four non-consecutive days. They will be served a standard breakfast, and then can leave the test centre for 3 hours. When they return, they will consume a bowl of soup, and then 45 minutes later will be provided with a lunch. They will make ratings of their appetite before, during and after they eat the soup and lunch.

What are the possible benefits and risks of participating?
Participants will benefit by receiving the free test food and will be paid a small sum (£45) on completion of the final day to compensate them for their time.
As the study involves consuming food, potential participants who have specific conditions that require special dietary controls (those with diabetes, or with allergies or aversions to any of the foods and drinks used) are excluded for their safety. The foods and ingredients used are standard products used within the concentrations normally used by consumers, and pose no risk to the study population.

Where is the study run from?
The study is conducted at the Ingestive Behaviour Unit at the University of Sussex, Brighton, UK.

When is the study starting and how long is it expected to run for?
The study started in May 2013 and ran for 5 months.

Who is funding the study?
Ajinomoto Co., Inc., Japan.

Who is the main contact?
Professor Martin Yeomans

Trial website

Contact information



Primary contact

Prof Martin Yeomans


Contact details

School of Psychology
University of Sussex
United Kingdom

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Acute effects of a combination of inosine monophosphate (IMP) and monosodium glutamate (MSG) on appetite and satiety in healthy volunteers


Study hypothesis

The addition of a combination of IMP/MSG to a neutral low-energy soup will enhance flavour and appetite when ingested but also signal the presence of protein, thereby enhancing protein-induced satiety.

Ethics approval

Science and Technology Cross-Schools Research Ethics Committee (C-REC) at Sussex University, 01/05/2013, MYUM0413

Study design

Within-participant design

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details below to request a patient information sheet




The study uses a preload-satiety design. On each of four test days, participants attend the research centre (Ingestive Behaviour Unit at Sussex University) between 0800 and 1000h to consume a fixed breakfast. They return 3 hours after breakfast to consume a test soup, and then 45 minutes later consume as much as they like of a test lunch. The key manipulations are the energy content (low-energy or high-energy protein) and the flavour characteristics (control or with added umami taste) of the soup.

Intervention type



Not Applicable

Drug names

Primary outcome measure

Satiety is indexed by amount consumed at the ad libitum test lunch, while the acute stimulation of appetite by umami is measured as the immediate change in desire to eat on tasting the test soup. This will be measured on all four test sessions.

Secondary outcome measures

1. Calculated compensation for additional energy in protein-soups relative to low energy control
2. Changes in the rated experience of appetite post-ingestion
3. Rate of eating and duration for ingestion of the soup

Outcomes will be measured on all four test sessions.

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

Healthy men and women aged 18-50 and who score less than 7 on the restraint scale of the Three Factor Eating Questionnaire

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. Individuals who were taking prescription medication (excluding the contraceptive pill)
2. Who smoked more than 5 cigarettes per week
3. Diabetic
4. Had a diagnosed eating disorder
5. Allergies or dietary intolerances to the foods used

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

School of Psychology
United Kingdom

Sponsor information


Ajinomoto Co., Inc (Japan)

Sponsor details

15-1 Kyobashi It-chome

Sponsor type




Funder type


Funder name

Ajinomoto Co., Inc (Japan) - PhD studentship

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Basic results (scientific)

Publication list

2014 results in:

Publication citations

  1. Results

    Masic U, Yeomans MR, Umami flavor enhances appetite but also increases satiety., Am. J. Clin. Nutr., 2014, 100, 2, 532-538, doi: 10.3945/ajcn.113.080929.

Additional files

Editorial Notes