The Effects of Fish Oil Supplementation on the Brain Health of Collegiate Football Athletes: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Effects of Fish Oil Supplementation on the Brain Health of Collegiate Football Athletes (NCT04796207), a randomized na study. The primary outcome is Changes in Brain Biomarkers Due to Sub-concussion Injury - Nf-L.

2. Clinical Question

The trial’s central question concerns a biomarker, not a reported clinical diagnosis or a measure of athletic performance. The registry describes Nf-L as a neuron-specific intermediate protein released upon injury to neurons and axons. Its purpose in this study is to assess biomarker change associated with sub-concussion injury across the season. The primary outcome lists baseline, Week 17, and Week 26 as measurement times.

The registry record does not report numerical Nf-L results, an estimated difference between groups, or a confidence interval for that difference. It therefore does not establish whether the groups’ biomarker patterns differed, how large any difference was, or how precisely it was estimated. The outcome description also does not identify a single contrast as the primary comparison among the listed times.

3. Trial Design

The registry identifies this as a randomized, quadruple-masked, parallel-group study. Participants were assigned to fish oil capsules or high-oleic safflower oil capsules. In a parallel-group design, participants remain in their assigned group while outcomes are compared across groups; the record does not describe any crossover between supplements. The stated enrollment is 38, and the study status is completed.

The fish oil arm description specifies 3 grams of DHA and EPA in a 2:1 weight ratio, taken 5 times a week for 25-weeks during the regular football season. The safflower oil arm description specifies 3 grams of high-oleic safflower oil on the same stated schedule and also mentions a 1:1 allocation ratio. The registry does not explain the masking procedures or identify the people included in the quadruple masking.

The record lists the study start as 2019-05-28 and primary completion as 2020-01-28. The phase is listed as NA. University of Arizona is named as sponsor. The stated study question concerns whether DHA/EPA supplementation reduces serum biomarkers of sub-concussion injury over a football season among collegiate football athletes.

These design details describe the intended comparison, but they do not establish how the trial was conducted in practice. The registry record does not report the randomization method, allocation concealment, participant flow, adherence, withdrawals, or whether the stated enrollment represents the number analyzed for the primary outcome. It also does not report a sample-size justification. Those omissions limit assessment of implementation and of how well the enrolled groups represent the intended study population.

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

Reasons for not completing this period:

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.

Population: NCAA football participants

6. Primary Endpoint

The registry lists the primary outcome as Changes in Brain Biomarkers Due to Sub-concussion Injury - Nf-L, measured over Baseline, Week 17, Week 26.

The primary outcome is change in plasma Neurofilament Light Chains (Nf-L), measured in pg/ml. The registry describes Nf-L as neuron-specific intermediate proteins released upon injury to neurons and axons. The outcome is intended to track a biomarker associated with sub-concussion injury during the football season. The listed measurement times are baseline, Week 17, and Week 26.

The endpoint is specified as a mean with a 95% Confidence Interval. In general, a mean describes the average measurement in a group, while a confidence interval communicates uncertainty around an estimate. A narrower interval generally indicates greater precision; a wider interval indicates less precision. Interpretation depends on knowing which estimate the interval accompanies and whether it represents a group mean, a change, or a between-group contrast.

The registry record does not report Nf-L values, changes from baseline, between-group estimates, or confidence limits. It also does not state how measurements at the listed times were combined into a primary comparison. As a result, the biological rationale and measurement schedule are described, but the magnitude and precision of any observed biomarker change cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry characterizes the primary endpoint as a continuous measure summarized by a mean and a 95% Confidence Interval. General statistical interpretation begins by distinguishing the measured quantity from the contrast of interest. A mean can describe the average Nf-L level within a group at a measurement time. A change estimate describes how that average differs from baseline. A between-group contrast compares the groups’ estimates. These summaries answer different questions, and the registry record does not report numerical values for any of them.

What does a confidence interval communicate?

In general, a confidence interval expresses uncertainty around an estimate under the analysis assumptions. It can help readers judge how precisely a mean or contrast has been estimated. It is not a range containing most individual measurements, and it does not replace the estimate itself. To interpret an interval for this trial, readers would need to know which quantity it accompanies, how it was calculated, and whether it describes a group mean or a comparison between groups. Although the registry specifies a 95% Confidence Interval as the dispersion measure, its numerical limits are not reported in the registry record.

Why do repeated measurements matter?

The outcome lists baseline, Week 17, and Week 26. In general, repeated measurements from the same participant are related rather than independent. An analysis that accounts for this relationship can use the measurements together, while a separate comparison at each time answers a more time-specific question and may create multiple opportunities to find an apparently notable result. The analysis method used for this endpoint, the handling of within-participant correlation, and the target contrast are not reported in the registry record. It is therefore not possible to determine whether the reported analysis, if any, addressed the repeated-measure structure.

Why can over-dispersion matter?

General explanation: over-dispersion occurs when observed variability is greater than a model assumes. If a model underestimates variability, uncertainty intervals may be too narrow and tests may overstate how much evidence the data provide. This concern is relevant only when the chosen model and data structure make it applicable. The registry record does not report the primary outcome model or a diagnostic assessment, so it does not establish whether over-dispersion was relevant to this continuous endpoint.

What can a planning calculation show?

General explanation: sample-size planning estimates the number of participants needed to detect a specified effect under chosen assumptions. Such calculations are prospective planning tools; they are not evidence that a completed trial had a particular probability of detecting an effect. The registry’s planning assumptions describe a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the effect to detect stated as a fraction of the observed effect. They also distinguish participants per arm for non-time-to-event outcomes from total events for time-to-event outcomes. The record does not report the trial’s own design justification. Planning illustrations should therefore be treated as assumption-dependent, not as observed power or as a substitute for outcome estimates.

What is not available for statistical review?

The record does not report the primary analysis model, a prespecified contrast, an adjustment strategy, p-values, or numerical Nf-L estimates. It does not describe handling of missing measurements, analysis populations, or sensitivity analyses. No recalculated estimates are included in the record. Without posted summary statistics, an independent unadjusted recalculation cannot be made, and there is no sponsor estimate in the registry record to compare with such a calculation. The absent details prevent a fuller assessment of the analysis assumptions and the robustness of the result.

10. Multiplicity, Missing Data and Analysis Populations

The primary biomarker is measured at baseline, Week 17, and Week 26, and the registry lists 3 outcome measures. Testing several outcomes or several time-specific contrasts can increase the chance of at least one apparently notable result by chance. General statistical practice may address this through a prespecified primary contrast, an adjustment for multiple comparisons, or a clear distinction between confirmatory and exploratory outcomes. The registry record does not report whether multiplicity was addressed or which outcome comparisons were prespecified.

The record reports 0 analyses and does not provide numerical outcome estimates. It also does not specify an analysis population, such as whether all randomized participants were included, or report the number with evaluable Nf-L measurements at each time. The number of participants analyzed is not reported in the registry record.

Missing data can affect estimates when participants lack measurements, particularly if missingness is related to outcome values or differs between groups. General approaches include analyzing available observations under explicit assumptions or using methods designed for incomplete repeated measurements. The appropriate approach depends on why observations are missing and on the analysis plan. The registry record does not report the extent, reasons, or handling of missing primary outcome data. It also does not describe imputation, sensitivity analyses, or deviations from an intention-to-treat analysis. These gaps make it impossible to assess how missingness or multiplicity may have affected the reported evidence.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent non-serious adverse event terms

The adverse-event record lists 12 participants at risk for serious adverse events in the fish oil group and 17 in the safflower oil group. It reports 0 affected by serious adverse events in each group. Deaths are recorded as 0 in both groups, and no top serious adverse-event terms are listed.

For other adverse events, the record lists 12 at risk and 12 affected in the fish oil group, and 17 at risk and 11 affected in the safflower oil group. These are group-level counts as recorded; they do not describe event severity, duration, recurrence, or whether events were considered related to the capsules. The record does not provide further detail about the other adverse events.

Counts of affected participants should be interpreted alongside the listed group denominators and the completeness of event reporting. The adverse-event figures alone do not establish that an intervention caused or prevented an event. The registry record does not explain why the adverse-event denominators differ from the stated enrollment, or whether all enrolled participants contributed to these safety counts.

12. What the Result Does, and Does Not, Mean

This record documents a randomized comparison of fish oil and high-oleic safflower oil capsules in collegiate football athletes, with plasma Nf-L as the primary biomarker outcome. It describes the intervention schedules, masking, study status, and measurement times. It also reports group counts for serious and other adverse events.

It does not report numerical primary outcome results or an analysis estimate. The record therefore cannot establish whether Nf-L changed over the season, whether changes differed between groups, or how precise any estimated difference might be. The absence of posted estimates is not evidence that the groups had identical outcomes; it leaves the size and direction of any difference unknown from this registry record.

The outcome is a biomarker measure, described as associated with injury to neurons and axons. A biomarker result would not by itself establish a diagnosis, long-term health outcome, or clinical benefit. The record does not report clinical outcome findings that would address those questions.

The serious adverse-event counts are zero in both groups, with deaths also recorded as zero. Those counts are descriptive and do not determine whether either supplement caused or prevented harm. The other adverse-event counts are reported without detailed event descriptions or attribution. Overall, the registry record supports a description of the study design and recorded safety counts, but does not provide enough outcome data to judge the primary comparison or its uncertainty.

13. Why This Trial Matters Statistically

This trial addresses a question about measuring a brain-related biomarker over a football season, rather than relying only on clinical diagnoses. The registry describes Nf-L as a neuron-specific protein released upon injury to neurons and axons, and identifies collegiate football athletes as the study population. The comparison of fish oil with high-oleic safflower oil gives the study a randomized parallel-group structure.

Statistically, the design raises useful questions about how to compare repeated biomarker measurements and how to report uncertainty around a group difference. Measurements at baseline, Week 17, and Week 26 can support different estimands depending on whether the focus is change at a particular time or the pattern across the season. Clear reporting of the target comparison, analysis population, missing data, and uncertainty is needed to interpret such an endpoint. Those analysis details and the numerical results are not reported in the registry record.

The registry record also illustrates why a completed status and a description of study procedures are not substitutes for outcome estimates. Without numerical results, readers cannot assess the size, direction, or precision of the primary comparison. The stated enrollment of 38 and the recorded adverse-event counts provide context, but they do not resolve that central evidence gap.

The statistical importance of the study record is therefore in the questions it makes visible: what a biomarker can capture, how repeated observations should be analyzed, and what information is needed for transparent interpretation. The record gives the study framework but not the numerical evidence needed to answer its primary question.

14. 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.

The most important trial-specific limitation for interpretation is that the registry record does not report numerical primary outcome results. It gives no Nf-L means, changes, between-group estimates, confidence limits, or p-values. Consequently, the primary comparison’s direction, magnitude, and precision cannot be assessed.

The primary outcome spans baseline, Week 17, and Week 26, but the registry does not identify a single primary contrast among these times or describe the repeated-measures analysis. It lists 3 outcome measures and reports 0 analyses, without describing whether multiplicity was considered. The analysis population, participant flow, and number with measurements at each time are not reported in the registry record.

The stated enrollment is 38, but the record does not provide a sample-size justification or explain how the enrollment target was chosen. It does not report adherence, withdrawals, missing data, or sensitivity analyses. These omissions prevent assessment of whether the planned and analyzed populations matched or whether incomplete follow-up could have influenced the findings.

The registry describes a population of collegiate football athletes and an intervention schedule during the regular football season. It does not report participant characteristics or further eligibility criteria. The findings’ applicability to other populations or settings therefore cannot be evaluated from this record. The safety information is limited to event counts; detailed descriptions and attribution are not reported in the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: The Effects of Fish Oil Supplementation on the Brain Health of Collegiate Football Athletes — NCT04796207.
• Registry record last updated 2025-05-09; status last verified 2025-04.
• Results first posted 2025-05-09.
• 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.

18. Record Summary

The study, NCT04796207, is titled The Effects of Fish Oil Supplementation on the Brain Health of Collegiate Football Athletes. It is listed as completed, randomized, quadruple-masked, and parallel-group, with enrollment of 38. University of Arizona is the sponsor. The record lists a start date of 2019-05-28 and primary completion date of 2020-01-28.

The comparison is fish oil capsules containing DHA and EPA versus high-oleic safflower oil capsules, taken 5 times a week for 25-weeks during the regular football season. The primary outcome is change in plasma Nf-L, measured in pg/ml at baseline, Week 17, and Week 26. The record reports 0 analyses and does not report numerical primary outcome results.

For serious adverse events, 0 affected participants and 0 deaths are listed in each group. Other adverse events are reported as affecting 12 participants in the fish oil group and 11 in the safflower oil group. The record does not provide additional outcome estimates or detailed event descriptions.