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UM: Monosodium Glutamate (MSG) and Adverse Effects (2013)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

To evaluate the prevalence of adverse symptomology in response to the ingestion of MSG in combination with a typical Indonesian meal.

Inclusion Criteria:
  • Healthy volunteers (age range 18 to 65) who were not self-identified MSG responders
  • Provided a small fee for participation.
Exclusion Criteria:
  • Prescription drug use within one or less week before the study began
  • Pregnant
  • History of any of the following conditions:
    • Bronchial asthma
    • General allergy symptoms
    • Epilepsy
    • Diabetes mellitus
    • Moderate or severe hypertension
    • Gastric or duodenal ulcer
    • Alcoholism
    • Drug dependence or psychiatric disease.
Description of Study Protocol:

Recruitment

  • Subjects were recruited through advertisements in three sub-districts of Yogyakarta municipality
  • To avoid demand bias, suggestive wordings such as MSG, Chinese Restaurant syndrome and adverse effect were not used in advertisement.

Design

  • Randomized, double-blind, crossover design
  • Participants were allocated randomly to each of three treatments successively on each day. The list for assigning participants to treatment was generated using simple randomization with crossover to ensure an equal number of subjects in each treatment.

Blinding used

  • Double-blinded
  • Random table was used to code the packages.

Intervention

  • Opaque capsules
  • Placebo: 1g pharmaceutical grade lactose
  • 1.5mg MSG (PT Ajinomoto, Indonesia)
  • 3mg MSG.

Statistical Analysis

  • The Friedman test was conducted using MINITAB (V 8.1)
  • Differences in period effect were tested separately for the three challenge days
  • If the probability level was less than 0.05, the statistical tests were considered significant.
Data Collection Summary:

Timing of Measurements

  • Subjects arrived in the morning after fasting for 10 hours
  • Blood pressure and pulse and respiratory rates were measured (in triplicate) and the subjects ingested three capsules containing MSG or placebo
  • A standardized breakfast was provided and consumed immediately after capsule ingestion
  • Blood pressure, pulse and respiratory rates were again measured and the subjects were asked to go about their normal activities (but to refrain from eating except for bread and snacks that did not contain added MSG)
  • Standardized lunches and dinners (without MSG) were also prepared and provided on test days
  • Participants completed symptoms questionnaires four times after breakfast (0.5, one, two and three hours).

Dependent Variables

Adverse symptomology:

  • Dizziness
  • Headache
  • Neck stiffness
  • Palpitation
  • Weakness
  • Chest pain/burning
  • Gastric
  • Nausea
  • Thirst
  • All others.

If symptoms were noted, intensity was ranked on a scale of one (low) to five (high).

Blood pressure, pulse and respiratory rates.

Independent Variables

  • Placebo
  • 1.5mg MSG
  • 3mg MSG.

 

Description of Actual Data Sample:
  • Initial N: 52 men and women
  • Attrition (final N): 52 men and women
  • Age: Mean age 29.6±6.5 years
  • Anthropometrics: Mean mass 53.4±7.4kg
  • Location: Indonesia.
Summary of Results:

Key Findings

  • There were no differences (P>0.05) in blood pressure, pulse and respiratory rates among the MSG (1.5 or 3.0g) or placebo treatment days at any of the time intervals measured
  • No subject reported an aftertaste
  • There was no difference (P>0.05) in period effects among the three challenge days
  • The incidence of nausea at 1.5g MSG was non-statistically higher than placebo but was also higher than that at 3.0g MSG
  • The incidence of each symptom was low; therefore, the intensities of the symptoms (symptom score) were summed for analysis. No difference (P>0.05) were found among the three treatment groups.

 

 

 

Author Conclusion:

The results from this study suggest that adverse effects are not elicited by MSG (at doses up to 3g) in healthy Indonesian subjects.

Funding Source:
University/Hospital: Department of Pharmacology, Faculty of Medicine Yogyakarta Indonesia
Reviewer Comments:
  • This study was the first to examine the issue of adverse responses to MSG in Indonesians and employed a complex food system together with capsules to minimize MSG taste and thus subject bias
  • No limitations noted.
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? Yes
  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? ???
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? 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? ???
  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)? No
  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? 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