Non-linear association between dietary fiber intake and cognitive function mediated by vitamin E: a cross-sectional study in older adults
Bibliographic record
Abstract
Background Emerging evidence suggests dietary fiber may prevent cognitive decline, but its dose-response relationship and underlying mechanisms remain unclear. This study investigates the non-linear association between dietary fiber intake and cognitive function in older adults and explores the mediating role of vitamin E. Methods This cross-sectional analysis of nationally representative National Health and Nutrition Examination Survey (NHANES) Data from 2011 to 2014 included 2,713 adults aged ≥60 years. Dietary fiber intake was assessed using two 24-h dietary recalls. Cognitive function was evaluated using a comprehensive battery comprising three standardized assessments: the Digit Symbol Substitution Test (DSST) to measure processing speed, the Animal Fluency Test (AFT) to assess executive function, and a Consortium to Establish a Registry for Alzheimer's Disease (CERAD) subtest to evaluate memory performance. Composite z -scores were calculated for each individual test and combined to generate a global cognition composite score. Generalized additive models (GAM) were applied to model non-linear relationships, and threshold effects were evaluated using two-piece-wise linear regression. Mediation analysis quantified the mediating role of vitamin E in the dietary fiber-cognitive function association, with effects assessed via the non-parametric percentile bootstrap method. Subgroup-specific sensitivity analyses demonstrated consistent findings. Results A J-shaped relationship between cognitive function and dietary fiber intake was identified using a two-piece-wise linear regression model. DSST scores reached a plateau at 29.65 g/day of fiber intake (likelihood ratio test P < 0.001), while composite z -scores reached a plateau at 22.65 g/day (likelihood ratio test P = 0.018). Below the inflection point, dietary fiber intake demonstrated a positive association with DSST scores (β: 0.18, 95% CI: 0.01–0.26, P < 0.0001), whereas above this threshold, the relationship became negative (β: −0.15, 95% CI: −0.29 to −0.02, P = 0.0265). Similarly, for composite z -scores, a positive association was observed below the inflection point (β: 0.01, 95% CI: 0.00–0.01, P = 0.0004), while the relationship appeared to saturate above this threshold (β: −0.00, 95% CI: −0.01–0.00, P = 0.9043). Mediation analysis revealed that vitamin E intake significantly mediated 85.0% ( P < 0.0001) of the association between dietary fiber intake and composite z -scores, and 86.8% ( P < 0.0001) of the association between dietary fiber intake and DSST scores. Conclusion Moderate dietary fiber intake is associated with optimal cognitive performance, largely mediated by vitamin E.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".