This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Encapsulated Juice Powder Concentrate for Preventing Common Cold Symptoms (NCT00778648), a randomized na study. The primary outcome is Number of Days With at Least Moderate (i.e. Moderate or Severe) Common Cold Symptoms..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00778648 |
| Phase | NA |
| Condition | Common Cold |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 543 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Charite University, Berlin, Germany |
| Results posted | Yes |
2. Clinical Question
Population
Participants in a trial concerning the common cold. The registry reports enrollment of 543 and describes the primary outcome as being measured within 6 months after a 2-month run-in period. Further eligibility criteria and participant characteristics are not reported in the registry record.
Intervention
Juice Plus, identified in the registry as a dietary supplement and described in the trial title as an encapsulated juice powder concentrate. Details of the supplement’s composition, dose, and administration are not reported in the registry record.
Comparator
Placebo, also identified as a dietary supplement. The registry does not describe the placebo’s composition or how it was made to resemble the intervention.
Primary question
What was the mean number of days with at least moderate common cold symptoms in the Juice Plus and placebo groups during the stated follow-up, and what does the registry’s reported analysis say about the comparison?
3. Trial Design
The registry describes a randomized, quadruple-masked, parallel-group trial of Juice Plus and placebo. It lists enrollment of 543 and reports 272 participants in the Juice Plus arm and 271 in the placebo arm for the primary outcome. The trial is marked completed. Its start is recorded as 2008-09, with primary completion in 2009-07. The phase is listed as NA.
The sponsor is Charite University, Berlin, Germany. The brief summary states that the primary objective was to determine the effect of an encapsulated juice powder concentrate on the number of days with at least moderate common cold symptoms over winter time. The primary outcome timeframe is specified as within 6 months after a 2-month run-in period.
Randomization indicates assignment to study groups by chance, while a parallel design means the groups are followed as separate arms. The registry labels masking as quadruple but does not identify which people involved in the trial were masked or describe how masking was maintained. Allocation procedures, eligibility criteria, participant flow, adherence, and the handling of withdrawals are not reported in the registry record.
The registry also identifies health-related quality of life and common-cold-related total costs, including direct and indirect productivity-loss costs, as secondary endpoints. Numerical results for these outcomes are not reported in the registry record. The design description alone does not establish how participants were recruited, how the supplement was used, or how outcomes were collected.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Juice Plus | Placebo |
|---|---|---|
| STARTED | 272 | 271 |
| COMPLETED | 263 | 266 |
| NOT COMPLETED | 9 | 5 |
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | Juice Plus | Placebo | Total |
|---|---|---|---|---|
| Participants analysed | 272 | 271 | 543 | |
| Age Continuous | years | 40.9 (SD 10.2) | 38.8 (SD 10.3) | 40.9 (SD 10.2) |
| Gender: Female | participants | 202 | 222 | 424 |
| Gender: Male | participants | 61 | 44 | 105 |
| Region of Enrollment: Germany | participants | 272 | 271 | 543 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Days With at Least Moderate (i.e. Moderate or Severe) Common Cold Symptoms., measured over within 6 months (after 2 months run-in period).
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | Number of days |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is the number of days with at least moderate common cold symptoms. The registry clarifies that this includes symptoms categorized as moderate or severe, and gives the unit as number of days. It reports the outcome as a mean, with a 95% confidence interval for each arm. The timeframe is within 6 months after a 2-month run-in period.
This endpoint represents symptom duration at a specified severity threshold. Counting days meeting that threshold focuses the measure on the duration of more than mild symptoms, rather than simply whether a participant had any cold symptoms. It is a continuous outcome in the registry’s analysis, and its mean describes the average number of qualifying days in each group. The registry’s stated primary objective also frames the outcome as days with at least moderate symptoms over winter time.
As a general statistical point, a mean provides a compact summary of a group’s outcome values, but does not show how those values are distributed among participants. The registry record does not report the distribution, standard deviations, individual participant data, or a separate definition of how a symptom day was counted. It also does not report details such as the diary or other instrument used to establish symptom severity. Those omissions limit assessment of how the endpoint was collected and how representative the mean is of participants’ varied experiences.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The reported mean number of days with at least moderate symptoms was 7.6 in the Juice Plus group, with a 95% confidence interval from 6.5 to 8.8. In the placebo group, the mean was 9.5, with a 95% confidence interval from 8.4 to 10.6. These are arm-level summaries; they are not a confidence interval for the difference between groups.
The registry reports an ANOVA comparison with p = 0.023. This is the posted inferential result for the primary comparison. In general, a p-value describes how compatible the observed data are with a specified null hypothesis under the assumptions of the analysis. It does not measure the size or practical importance of a group difference, and it is not the probability that the null hypothesis is true. The registry record does not provide the ANOVA test statistic, degrees of freedom, model specification, or a confidence interval for the between-group contrast.
The arm means indicate that the observed average was 7.6 days in the Juice Plus group and 9.5 days in the placebo group. The uncertainty intervals describe uncertainty around each arm’s mean, not directly around the contrast. A reader should not treat the two arm-specific intervals as a substitute for an interval around the comparison. The reported p-value supplies evidence from the sponsor’s comparison, but without a contrast estimate and its uncertainty, the magnitude and precision of the group difference cannot be fully assessed from the registry results.
The registry reports 272 participants for the Juice Plus arm and 271 for placebo in the primary outcome. The outcome summaries therefore describe the posted group results, but the analysis population and the number of participants with observed endpoint data are not separately explained. It is not reported in the registry record whether all randomized participants were included in the ANOVA or how missing outcome data were handled.
The result should be read as a reported statistical comparison of mean symptom-days in this trial, not as a complete account of the evidence. The registry does not report an adjusted analysis, a prespecified analysis plan, or results for the listed secondary endpoints. The result alone cannot establish the clinical importance of the difference or explain how it might apply beyond the participants and procedures in this study.
9. Statistical Methods Explained
What does the mean describe?
The primary outcome is continuous and is reported as a mean number of days. A mean is the arithmetic average of observed outcome values in a group. It gives one summary of the group, but does not reveal whether most participants had similar values or whether the mean reflects a wider spread of experiences. The registry reports confidence intervals for the means but does not report standard deviations or other descriptions of the outcome distribution.
As a general statistical explanation, a confidence interval expresses uncertainty around an estimated quantity under the assumptions used to calculate it. The posted 95% confidence intervals are attached to the separate arm means. They do not directly give the uncertainty around the difference between arm means. A contrast estimate and its confidence interval would make the size and precision of the comparison more directly assessable. Those are not reported in the registry record.
What does the ANOVA result represent?
The registry identifies ANOVA as the method for the two-group comparison and reports p = 0.023. In general, analysis of variance compares group means by relating variation among group means to variation within groups, under the assumptions of the selected model. The registry does not provide enough detail to identify the exact model or its assumptions, such as whether any covariates were included or how the outcome distribution was assessed.
The p-value is evidence from the stated test, not an estimate of the amount of difference. It does not give the probability that the observed result arose by chance, nor does it establish that an effect is clinically important. Interpretation also depends on the analysis being appropriate for the outcome and on the analysis plan, which is not reported in the registry record. No test statistic or degrees of freedom are posted.
Why are arm-specific intervals not enough?
Each interval quantifies uncertainty for one arm’s mean. A comparison concerns the contrast between arms, whose uncertainty depends on the variability and sample sizes in both groups and on the statistical method used. It is therefore not appropriate to infer the interval for the contrast by treating either arm’s interval as if it were the comparison interval. The registry gives no directly reported interval for the contrast.
A simple unadjusted re-calculation of the comparison is not estimable from the posted summary statistics in the registry record. The record supplies the group means, group sizes, and arm-level confidence limits, but the comparison fields do not contain a numerical contrast estimate or confidence limits. The posted ANOVA result remains the available inferential comparison; it should not be replaced with an invented contrast or precision estimate.
What can a planning illustration tell a reader?
Sample-size calculations based on an observed effect are planning illustrations, not evidence about the trial’s original design or its achieved power. The stated illustration assumptions are a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the effect to detect defined as a stated fraction of the observed effect. Such calculations address the sample size that would be needed under those assumptions for a chosen power target. They do not show the probability that this completed trial detected an effect, and they do not establish that the original trial was planned using these assumptions.
The trial’s own sample-size justification and design assumptions are not reported in the registry record. Numerical sample-size planning results are not reported in the registry record. Any planning illustration should consequently be kept separate from the observed trial results and should not be interpreted as an additional analysis of participants in the trial.
Why does variability matter?
In general, variability describes how dispersed individual observations are around a group summary. Greater variability can make a mean less precise for a given sample size and can affect the suitability of a model’s assumptions. For a continuous outcome, information about spread can help readers assess how much the group mean represents a typical participant. The registry does not report standard deviations or the participant-level distribution for this endpoint, so those features cannot be evaluated from the posted summaries.
The record’s presentation of means and confidence intervals is useful for describing average outcomes and their estimated precision, but it does not provide all information needed to reproduce the ANOVA or to assess model fit. The analysis method and p-value should therefore be interpreted as the registry reports them, with the limits of the available model detail in mind.
10. Analyses Reported by the Sponsor
| Method | Estimate | 95% CI | P-value |
|---|---|---|---|
| ANOVA | not reported | 0.023 |
The registry reports the sponsor’s analysis as an ANOVA comparison of the Juice Plus and placebo groups, with p = 0.023. It does not report a numerical estimate or confidence interval for the between-group contrast. The posted means and 95% confidence intervals are for each arm separately, rather than for the contrast.
A simple unadjusted re-calculation of the comparison is not estimable from the posted summary statistics in the registry record. The registry marks no discrepancy between its reported analysis and a re-calculation. Accordingly, there is no reported conflicting re-calculated result to set against the ANOVA. The sponsor’s posted analysis is the available comparison result.
That does not make the missing contrast estimate or analysis details available. Readers can identify the reported method and p-value, but cannot assess a directly reported contrast interval, reproduce the model, or determine from this record whether the analysis used adjustment. The result should be interpreted at the level of detail actually reported.
11. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary endpoint and describes secondary endpoints concerning mean health-related quality of life and mean common-cold-related total costs, including direct and indirect productivity-loss costs. It does not report numerical results for those secondary outcomes. The number of posted secondary outcomes is 1, while the record lists 2 outcome measures. The registry does not explain this difference in counts.
When a study examines multiple outcomes or makes multiple comparisons, the chance of at least one apparently notable result can increase. As a general statistical matter, a prespecified multiplicity strategy can clarify how such testing is handled. A multiplicity adjustment or other plan for interpreting several outcomes is not reported in the registry record. The reported p-value should therefore be understood as the posted result for the primary comparison, without assuming any unreported adjustment or broader testing strategy.
The registry does not report whether interim analyses were planned or conducted. It does not report a statistical analysis plan, the definition of analysis populations, or whether the primary analysis followed intention-to-treat principles. It also does not state how protocol deviations, nonadherence, withdrawals, or missing endpoint values were handled.
Missing data can affect a group comparison if availability of measurements is related to participants’ outcomes or differs between groups. As a general explanation, an analysis that excludes participants without observed outcomes can target a different set of participants from one that accounts for all randomized participants, depending on its assumptions and methods. The posted record does not provide enough information to determine which approach was used. Although arm sample sizes are reported, the number of participants with observed primary outcomes and the analysis population are not separately specified.
The trial’s own sample-size justification is not reported in the registry record. The available planning assumptions based on the observed effect are illustrations, not documentation of the original design. They cannot answer whether the original sample size was selected for the primary outcome or how missing data and multiple outcomes were anticipated.
12. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Juice Plus | 0 | 272 | 0.0% |
| Placebo | 0 | 271 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Juice Plus | 0 of 272 |
| Placebo | 0 of 271 |
For serious adverse events, the registry reports 0 affected participants among 272 at risk in the Juice Plus group and 0 among 271 at risk in the placebo group. It also reports 0 participants with other adverse events among 272 at risk in the Juice Plus group and 0 among 271 at risk in the placebo group. The deaths field is null for both groups, so deaths are not reported in the registry record.
These entries describe the counts posted in the registry; they do not establish that no events occurred outside the reporting captured there. The record does not provide event definitions, observation duration for safety, collection methods, event-level descriptions, or information about withdrawals related to adverse events. The list of top serious adverse-event terms is empty.
As a general statistical point, a zero count in a group is an observed count, not proof that the underlying event risk is zero. Safety interpretation depends on how events were solicited, defined, followed, and reported, as well as on the number of participants observed. Those details are not reported in the registry record. These figures should therefore be read as the posted adverse-event counts and not as a complete account of safety evidence.
13. What the Result Does, and Does Not, Mean
The posted data show a mean of 7.6 days with at least moderate symptoms in the Juice Plus group and 9.5 days in the placebo group, with arm-specific 95% confidence intervals of 6.5 to 8.8 and 8.4 to 10.6, respectively. The registry’s ANOVA comparison reports p = 0.023. These registry entries describe the primary outcome and its reported statistical comparison in this randomized, quadruple-masked trial.
The result does not, by itself, quantify the between-group contrast with a confidence interval, establish the clinical importance of the observed group means, or explain the analysis model in enough detail to reproduce it. The arm-specific confidence intervals are not a substitute for a confidence interval on the contrast. A p-value is not a measure of effect size and does not establish a causal or clinical conclusion on its own.
The registry record also does not report the analysis population, missing-data methods, interim analyses, adjustment for multiple outcomes, or the trial’s own sample-size justification. These absences limit assessment of the robustness and precision of the analysis. Results for the listed secondary endpoints are not reported in the registry record, so the primary result cannot be placed alongside numerical findings for health-related quality of life or costs.
The findings pertain to the trial as described in the registry. The record does not provide enough information about participant eligibility, baseline characteristics, intervention use, outcome collection, or follow-up completeness to establish how broadly the group results apply. The appropriate statistical reading is therefore bounded: the registry reports different arm means and an ANOVA p-value, while important details needed for a fuller appraisal are not reported.
14. Why This Trial Matters Statistically
This trial illustrates why a group comparison should be read through both its estimated outcomes and the information available about their uncertainty. The registry reports means and confidence intervals for each arm, and separately reports an ANOVA p-value. Those quantities answer related but distinct questions: the means describe the observed average in each group, the arm-specific intervals describe uncertainty around those averages, and the p-value reports the result of the stated comparison test.
The distinction matters because an interval for each group is not an interval for the contrast. A direct estimate and confidence interval for the contrast would make the size and precision of the comparison clearer. The registry record does not report these. This is a useful example of how an inferential result can be posted without all the information a reader might want for judging its magnitude or reproducing the analysis.
The endpoint also makes the summary choice important. A mean number of symptom-days describes average duration at or above the specified severity threshold, but does not show the distribution of individual outcomes. Without measures of spread or participant-level data, readers cannot determine how evenly that mean represents the group. The method and outcome details that would support a fuller distributional assessment are not reported in the registry record.
Finally, interpretation depends on information beyond a p-value: analysis populations, missing-data handling, multiplicity, and the prespecified plan all shape how results should be understood. These details are not reported. The trial is therefore a practical case in distinguishing what the registry result directly establishes statistically from what remains uncertain because of incomplete reporting.
15. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
Important design and analysis details are not reported in the registry record. These include eligibility criteria, participant characteristics, the randomization procedure, the people covered by quadruple masking, and the procedures used to maintain masking. The descriptions of the Juice Plus supplement and placebo do not include composition, dose, or administration details.
The outcome definition is limited to the number of days with moderate or severe symptoms. The registry does not describe the symptom instrument, data-collection procedures, or how a day qualified for inclusion. It also does not report the outcome distribution or standard deviations. These omissions make it difficult to assess measurement properties and the extent of variation among participants.
The comparison is reported as ANOVA with p = 0.023, but the model specification, test statistic, degrees of freedom, covariate adjustment, and contrast estimate are not reported in the registry record. The arm-specific confidence intervals do not provide direct uncertainty for the contrast. A simple unadjusted re-calculation is not estimable from the posted summary statistics.
The record does not report participant flow, endpoint completeness, adherence, analysis populations, missing-data methods, interim analyses, multiplicity handling, or the original sample-size justification. It also does not provide numerical results for the listed secondary endpoints. These limits constrain evaluation of bias, precision, and reproducibility. The safety reporting supplies zero counts for reported adverse-event categories but does not provide the event definitions, ascertainment details, or safety follow-up information needed for a fuller assessment.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: Encapsulated Juice Powder Concentrate for Preventing Common Cold Symptoms — NCT00778648.
- Registry record last updated 2010-10-05; status last verified 2010-09.
- Results first posted 2010-10-05.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
19. Record Summary
NCT00778648 is a completed, randomized, quadruple-masked, parallel-group trial sponsored by Charite University, Berlin, Germany. It compared the dietary supplements Juice Plus and placebo and reports enrollment of 543. The primary endpoint was mean number of days with at least moderate common cold symptoms, measured within 6 months after a 2-month run-in period.
The posted primary means were 7.6 days for Juice Plus and 9.5 days for placebo, with 95% confidence intervals of 6.5 to 8.8 and 8.4 to 10.6, respectively. The registry reports an ANOVA comparison with p = 0.023. It does not report a confidence interval for the between-group contrast or key details of the analysis population and missing-data handling. Serious and other adverse-event counts were 0 in both groups; deaths are not reported in the registry record.