EAL

UM: Umami Compounds and Sodium (2013)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To study effects of umami substances in two groups of low-salt and high-salt preference subjects
To examine how the flavor-enhancing properties of umami affect the acceptance of low-salt products when subjects were repeatedly exposed to these products
To study the hypothesis that enhancing the overall flavor increases the palatability of reduced-salt soups and thus help over the period of initial loss of taste when salt is reduced in the diet.

Inclusion Criteria:

Volunteers:

Students
University staff members.

Exclusion Criteria:

None identified.

Description of Study Protocol:

Recruitment

Volunteers were students and university staff members. Volunteers received a packet of coffee and cookies after completing the study.

Design

Randomized crossover trial.

Intervention

Subjects were tasting soups with and without umami (lentil, mushroom, leek-potato and minestrone)
Soups presented in random order
Umami included MSG and the 5’-ribonucleotides IMP and GMP.

Statistical Analysis

Repeated measures of analysis of variance (ANOVA)

Umami addition and type of soup were used as within-subject sources of variance
Low or high-salt preference groups were used as between-subject variables.

Data Collection Summary:

Timing of Measurements

Eight tasting sessions were done with all subjects over eight weeks:

Tasting sessions one and eight: All four soups were tasted with and without umami
Tasting sessions two to seven: Two soups with and without umami alternated with two different soups with and without umami.

Dependent Variables

Pleasantness:
- Nine-point scale used
- Scale of "extremely unpleasant " to "extremely pleasant"
Saltiness:
- Nine-point relative-to-ideal scale
- Scale from "not nearly salty enough" to "much too salty"
- The middle of the scale was listed as "just right."
Taste intensity: Nine-point scale from "weak" to "strong."

Independent Variables

Umami in soups: Mixture of 0.2% MSG, 0.05% IMP and GMP
Sodium content in soups:
- Low-salt preference group: 0.3% NaCl
- High-salt preference group: 0.5% NaCl.

Control Variables

Soups all presented in random order
Soups presented at 60°C
Black pepper was 0.02% in all soups
Hunger and thirst scales used prior to eating: Nine-point scale from "not thirsty/hungry at all" to "extremely thirsty/hungry."

Description of Actual Data Sample:

Initial N: 45 volunteers
Attrition (final N): 44 volunteers (35 females, nine males)
Age:
- Range: 19 to 47 years
- Mean: 27 years
Anthropometrics: Crossover trial, subjects served as own control
Location: University of Helsinki, Finland.

Summary of Results:

Key Findings

Overall effect of umami:

Increased pleasantness of all four soups, P<0.001
Increased taste intensity ratings, P<0.001
Increased the ideal saltiness ratings to near optimum, P<0.001.

Other Findings

Saltiness:
- The ideal saltiness ratings were different in low and high-salt groups, P<0.003. The low-salt group rated saltiness closer to the ideal than the high-salt groups.
- The change in ideal saltiness when umami was added was higher in the high-salt group than in the low salt-group, P< 0.024
Taste Intensity: The low salt group rated taste intensity higher than the high salt group, P=0.047
Pleasantness: No significant differences seen between groups.

Author Conclusion:

Umami increased the pleasantness, taste intensity and ideal saltiness of soups
The effect was observed at the beginning of the study and it remained the same until the end
This provides support for the positive effect of MSG on food palatability during restricted sodium intake
This study also used less MSG that in previous studies due to the combined and synergistic use of MSG, IMP and GMP
Umami substances are able to enhance other flavors of food and increase the pleasantness of reduced-salt foods.

Funding Source:

Industry:

Umami Manufacturers Association of Japan

Food Company:

Reviewer Comments:

Inclusion and exclusion criteria and recruitment methods not well described.

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?	No
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?	No
	2.2.	Were criteria applied equally to all study groups?	???
	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?	???
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)	Yes
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	Yes
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	Yes
	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?	???
	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%.)	No
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	???
	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?	N/A
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	Yes
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	Yes
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	N/A
	6.6.	Were extra or unplanned treatments described?	N/A
	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?	Yes
	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)?	Yes
	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?	No
9.	Are conclusions supported by results with biases and limitations taken into consideration?		No
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	No
10.	Is bias due to study's funding or sponsorship unlikely?		???
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	???