EAL

UM: Role of Umami in the Regulation of Energy Intake (2014)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To determine the effects of consumption of soup (beef consommé) pre-loads of a fixed size containing different concentrations of monosodium L-glutamate (MSG) on appetite following pre-loads
To assess and track, when no soup was consumed, the motivation to eat by measuring the amount of food eaten in test meals.

Inclusion Criteria:

Normal weight for height (mean BMI 21.1)
Not currently dieting to lose weight.

Exclusion Criteria:

Failure to complete all scheduled experimental sessions.

Description of Study Protocol:

Design

Study One	Study Two	Study Three
Soup pre-load Motivational rating for 60 minutes	Soup pre-load 30-minute interval Test meal	Soup pre-load Two-minute interval Test meal Post-meal Interval meal motivational

Individual subjects were tested on the same day of the week, usually with one week between each treatment
The subjects were blinded to the true purpose of the studies
There were four types of pre-load:
- Beef consommé (see Table One for composition) with no added MSG
- Beef consommé with 10% added MSG (Study Two only)
- Beef consommé with 20% added MSG
- No pre-load.
The soup base was reconstituted at a level of 1.82g per 100ml of water (percentage of MSG is percent dry weight). The soups were served hot, with 265ml in Studies One and Three and 220ml in Study Two (energy value of each serving was less than 10kcal).
Appetite was assessed using visual-analog ratings of desire to eat, hunger, fullness and prospective consumption (for example, "How much food do you think you could eat?") and the amount of food eaten in a lunchtime test meal
Sensory and affective ratings of the soup pre-loads were made during their consumption on eight visual-analog scales:
- Thick
- Salty
- Filling
- Savory
- Meaty
- Greasy
- Satisfying
- Pleasant.

Blinding Used

Subjects were blinded.

Intervention

Four types of pre-load:

Beef consommé (see Table One for composition) with no added MSG
Beef consommé with 10% added MSG (Study Two only)
Beef consommé with 20% added MSG
No pre-load.

Statistical Analysis

The initial scoring of the motivational rating scales was carried out blind to the identity of the pre-load conditions. Energy intakes were calculated with reference to standard good composition tables and manufacturer's data. Statistical analysis was carried out using repeated measures ANOVA and planned a priori to two sample comparisons were made using Student's T-test (two-tail probabilities are reported).

Data Collection Summary:

Timing of Measurements

Each study was conducted according to within subjects design and the pre-loads were administered in a counterbalanced order. As far as possible individual subjects were tested on the same day
of the week, usually with one week between each treatment.

Dependent Variables

Subjective motivational rating:
- Appetite: Visual-analog ratings of desire to eat, hunger, fullness and prospective consumption (for example, "How much food do you think you could eat?"), and the amount of food eaten in a lunchtime test meal
- Sensory and affective ratings:
  - Thick
  - Salty
  - Filling
  - Savory
  - Meaty
  - Greasy
  - Satisfying
  - Pleasant.
Food intake:
- Soup ratings
- Motivational ratings.

Independent Variables

MSG-supplemented soup pre-loads.

Control Variables

MSG-supplemented soup pre-loads:

Beef consommé (see Table One for composition) with no added MSG
Beef consommé with 10% added MSG (Study Two only)
Beef consommé with 20% added MSG
No pre-load.

Description of Actual Data Sample:

Initial N: 36 undergraduate volunteers (23 women, 13 men)
Attrition (final N): 32 subjects (four subjects failed to complete all of their scheduled experimental sessions)
Anthropometrics: BMI 21.1
Location: United Kingdom.

Summary of Results:

In Study One, 20% MSG-supplemented soup was rated as significantly more savory, more satisfying and more pleasant than the 0% MSG (unsupplemented) soup
An immediate decrease in appetitive motivational ratings and an increase in fullness; this was significantly different from the no-pre-load condition. The main effect of pre-load, smallest F(2,22)=3.47, P<0.05.
Appetitive ratings increased and fullness decreased during the subsequent 60 minutes. The main effect of time, F(6,66)=12.94, P<0.001
There were no significant differences in the effects of the two soup pre-loads, but indicates a somewhat more rapid recovery of hunger following the 20% MSG-supplemented soup
In Study Two, ANOVA revealed no significant effect of pre-load on test meal food intake [F(3,30)=0.40]
Intake was somewhat higher following the 20% MSG-supplemented soup compared with the 0% MSG soup [T(10)=2.05, P<0.1]
In Study Three, there was no significant effect of pre-load type on test meal food intake [F(2,16)=0.12]. Indeed, intakes were very similar in all three conditions.
Immediately following consumption of the soup pre-loads but before the test meal were significantly lower and fullness was significantly higher compared with the no pre-load condition [smallest F(2,16)=3.97, P<0.05].
There were no differences between the two soup pre-loads on these ratings. Immediately after the test meal, motivation to eat was reduced to a similar low level for all three pre-load conditions
During the next three hours, motivation to eat increased toward the level present before the pre-loads were consumed (baseline)
The rate of recovery was more rapid following the 20% MSG-supplemented soup compared with the 0% -MSG soup and when no pre-load was given
ANOVA confirmed these results, revealing a significant pre-load-times-time interaction for desire to eat and hunger [F(6,48)= 4.84, P<0.001 and F(6,48)= 2.32, P<0.05, respectively]
A significant main effect of time was present for all ratings [smallest F(3,24)=40.93, P<0.001]. There were no significant main effects of pre-load [largest F(2,16)=0.70].

Author Conclusion:

The present findings indicate salient sensory stimuli can promote increases in appetite. Although motivational ratings were reduced immediately following the soup pre-loads, this was probably cognitively mediated.
Cognitive influences were unlikely to be present; stimulation of motivation to eat was observed
Future studies should investigate the extent to which this might be accompanied by increased food intake.

Funding Source:

Industry:

International Glutamate Technical Committee ; products supplied by Ajinomoto Company, Inc., Paris, France

Reviewer Comments:

Study design was not properly discussed. It is a crossover, single-blinded study, with one week washout period between the treatments. Subjects were not randomized for three studies. All the subjects participated in all three studies, but this not clearly explained.
Demographic details and exclusion criteria is required
The study does not have a representative sample
Energy intake was calculated but not correlated with motivational ratings
Authors hypothesized that cognitive influences were unlikely to be present and stimulation of motivation to eat was observed. No cognitive scale was used in the study. Further exploration on cognitive influence on motivational ratings are required.
Observations are based on acute study; need a long-term study to draw conclusions.

Quality Criteria Checklist: Primary Research
Relevance Questions
	1.	Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)	Yes
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	Yes
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	Yes
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	Yes

Validity Questions
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	Yes
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	Yes
2.	Was the selection of study subjects/patients free from bias?		No
	2.1.	Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?	???
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	No
	2.4.	Were the subjects/patients a representative sample of the relevant population?	No
3.	Were study groups comparable?		Yes
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	No
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	???
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	N/A
	3.4.	If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?	N/A
	3.5.	If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)	N/A
	3.6.	If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?	N/A
4.	Was method of handling withdrawals described?		No
	4.1.	Were follow-up methods described and the same for all groups?	No
	4.2.	Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)	Yes
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	No
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	N/A
5.	Was blinding used to prevent introduction of bias?		No
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	No
	5.2.	Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)	No
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	N/A
	5.4.	In case control study, was case definition explicit and case ascertainment not influenced by exposure status?	N/A
	5.5.	In diagnostic study, were test results blinded to patient history and other test results?	N/A
6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?		Yes
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	Yes
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	Yes
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	N/A
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	No
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	No
	6.6.	Were extra or unplanned treatments described?	No
	6.7.	Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?	Yes
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	N/A
7.	Were outcomes clearly defined and the measurements valid and reliable?		Yes
	7.1.	Were primary and secondary endpoints described and relevant to the question?	Yes
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	Yes
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	No
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	Yes
	7.5.	Was the measurement of effect at an appropriate level of precision?	Yes
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	No
	7.7.	Were the measurements conducted consistently across groups?	Yes
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		Yes
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	Yes
	8.2.	Were correct statistical tests used and assumptions of test not violated?	Yes
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	Yes
	8.4.	Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?	N/A
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	No
	8.6.	Was clinical significance as well as statistical significance reported?	Yes
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	N/A
9.	Are conclusions supported by results with biases and limitations taken into consideration?		Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	Yes
10.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes