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

Testing for the presence of metabolic abnormalities that might affect children's response to ingestion of aspartame. Focusing on determining levels of alpha aspartyl-phenylalanine hydrolase activity as baseline and and at the end of an aspartame diet period.

Inclusion Criteria:
  • Normal children ages three to five years
  • School-aged children six to 10 years of age described by their parents as sensitive to sugar.
Exclusion Criteria:

Not stated.

Description of Study Protocol:


Recruitment methods not given.


Subjects and their families each followed a different diet in each of three consecutive three-week periods.

  • One diet three-week period was high in sucrose with no artificial sweeteners
  • One diet three-week period was low in sucrose and contained aspartame
  • One diet three-week period was low in aspartame and sucrose and contained saccharin (the placebo).

Blinding Used  

Children, families and research staff were blinded to the sequence of the diets.

Statistical Analysis

Variables were analyzed with paired T-test or repeated measures ANOVA.


Data Collection Summary:

Timing of Measurements

Plasma amino acid analyses were carried out

  • At baseline (fasting)
  • At three, six and nine weeks (post-prandial).

Dependent Variables

  •  Alpha-Asp-Phe hydrolase activity, measured in erythrocytes
  •  Plasma amino acids measured by venous blood sample
  •  Cognitive behavior.

Independent Variables

  • One three-week diet low in sucrose and contained aspartame
  • One three-week diet high in sucrose with no artificial sweeteners
  • One three-week diet low in aspartame and sucrose and contained saccharin (the placebo).
Description of Actual Data Sample:

Initial N

  • 23 school-aged children
  • 25 preschool children.

Age, Ethnicity, Other Relevant Demographics

Not given.


Not given.


University of Iowa.


Summary of Results:

Serum Amino Acid Levels


Fasting Baseline

Sucrose (Post-Prandial)

Aspartame (Post-Prandial)

Saccharin (Post-Prandial)
Phenylalanine (umol  per L)



 64.0± 15.9

 72.3 ±13.1b



 52.2 ±11.6a

 62.2± 12.1

 71.2 ±13.0b

Aspartate (umol per L)
Asp-Phe (umol per L)
<0.5umol per L

 All data are mean±SD
a Significantly lower than postprandial values, P>0.05
b Significantly different than sucrose and saccharin diets, P<0.05.

Other Findings

Aspartame was not associated with any significant cognitive or behavioral effects in either preschool or school-aged children.

Author Conclusion:

Authors saw no biochemical evidence of toxicity or excessive accumulation of alpha-Asp-Phe. Fasting and post-prandial plasma alpha-Asp-Phe were below detection limits for children on all diets. Phe and Asp were higher during aspartame diet but remained within normal limits.

Funding Source:
Government: NIH
University/Hospital: University of Iowa College of Medicine, Vanderbilt University
Reviewer Comments:

Investigators did not give dose of aspartame.

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) No
  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? ???
  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? ???
  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? ???
  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")? Yes
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? ???
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? ???
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? Yes
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? 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? Yes
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? No
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? N/A
  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)? ???
  8.6. Was clinical significance as well as statistical significance reported? No
  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