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 investigate the effects of MSG and inosine monophosphate (IMP) supplementation in low-energy broth pre-loads on subsequent appetite, energy intake and food choice, using a large sample.

Inclusion Criteria:

Female, 30 to 45 years old
Normal BMI
Non-smoking
Non-heavy-drinking
Not dieting to gain or lose weight
Willing to consume the test foods.

Exclusion Criteria:

Pregnant or breastfeeding
Food allergies
History of type 1 diabetes or diabetes mellitus and other uncontrolled endocrine diseases
Dysgeusia and digestive disease.

Description of Study Protocol:

Recruitment

Flyers.

Design

Randomized crossover with subjects serving as own control.

Blinding Used

Double blinded.

Intervention

Standardized chicken broth with either 1g of MSG (MSG) or 1g MSG and 0.1g IMP (MSG+) or the control broth. During the three test sessions, a standard 400kcal lunch was eaten within 30 minutes. Soup pre-load was served two hours later and a snack meal buffet was served 15 minutes after the pre-load was finished. Subjects ate and drank as much or little of the buffet foods and water in 30 minutes. They could request additional portions of any test snack.

Statistical Analysis

ANOVA for energy intake, test pre-load characteristic ratings and appetite motivational ratings. Least square means were used with Tukey corrections to compare test pre-load characteristics.

Data Collection Summary:

Timing of Measurements

Pre-load characteristic ratings at time of pre-load. Appetite motivational ratings immediately before and after
lunch, two hours after lunch, immediately after the pre-load, after the snack and 45 and 90 minutes after snack.

Dependent Variables

Energy and nutrient intake: All snacks and water were weighed prior to being served and re-weighed after the subjects had finished eating. Calculations used food labels and USDA database.
Hunger and fullness: Used 100mm visual analog scales.

Independent Variables

MSG and MSG with IMP.

Control Variables

A 200ml low-energy chicken broth
Standard lunch of 400kcal two hours before the test
A total of 15 snacks of varying taste and fat content totaling 2,230kcal
- Four high-fat savory
- Four low-fat savory
- Three high-fat sweet
- Five low-fat sweet.
Subjects ate alone in their individual room
Subjects were asked to eat similar foods and keep the amount of food eaten and physical activities in the 24 hours before each test as consistent as possible
No alcohol during the 24 hours prior to the test
During the test session, subjects were to remain seated with the exception of bathroom breaks and stretching. They were allowed to read anything that was not food-related.
No food other than what was given was allowed
Phone usage was not permitted.

Description of Actual Data Sample:

Initial N: 100 females
Attrition (final N): 86 females
Age: 37.9±0.53 years
Anthropometrics: BMI 22.2±0.19
Location: New Jersey.

Summary of Results:

Findings

Ratings for liking, pleasant and refreshing were significantly higher for the MSG and MSG+ broths than for the control broth (all P<0.001)
Total energy (all 16 test snacks combined) was highest after the control broth and less after the MSG broth. The difference between the MSG and control broth was significant; the impact was marginal. Compared to control, MSG pre-load decreased energy intake from sweet snacks and high-fat snacks (P<0.05). MSG+ did not significantly influence snack intakes in comparison to control. There were no differences between MSG and MSG+ in all comparisons.
Subjects consumed a similar amount of CHO and fat after the conditions. There was no difference in the amount of protein intake but subjects consumed a significantly higher percentage of energy intake from protein to total energy following MSG vs control (P<0.05) while no differences from CHO and fat were detected.
Significantly less added sugar and energy from fat was consumed after MSG vs. control (P<0.05) while no difference was found between either MSG+ and control or MSG and MSG+. Total sodium intake was not different across the three broth pre-loads.
Appetite ratings were not different across the three pre-loads
For hunger ratings and ratings of fullness, there was a significant effect of time (P<0.0001). There was no significant effect of broth pre-load over the testing period, nor was there any significant effect for pre-load times time interaction. Ratings for prospective consumption, desire to snack and thirst were also not different across the three pre-load conditions.

Author Conclusion:

There is a potential role of MSG addition to a low-energy broth pre-load in subsequent energy intake and food choice.

Funding Source:

Reviewer Comments:

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?	Yes
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	Yes
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?		Yes
	4.1.	Were follow-up methods described and the same for all groups?	Yes
	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?	Yes
	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?		Yes
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	Yes
	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.)	Yes
	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?	No
	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?	N/A
	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?	Yes
	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?	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