B vitamins, fiber, and Bacteroides as predictors of anxiety and depression in ALS: structural model in a cross-sectional sample
A nutritional latent factor comprising vitamins B1, B2, B9, C, and fiber showed an inverse association with anxiety and depression in 48 ALS patients, accounting for only 19% of the variance in psychological distress.
| Population | 48 adult patients with ALS (bulbar or spinal onset) recruited across multiple regions of Spain |
|---|---|
| Exposure | Latent nutritional factor: intake of vitamins B1, B2, B9, C, and dietary fiber (assessed by 24-h dietary recall and food frequency questionnaire) |
| Comparator | No control group; path analysis within a cross-sectional predictive model |
| Outcome | Emotional distress (anxiety + depression — latent factor); Bacteroides abundance (mediator); Stool consistency — Bristol Stool Scale (mediator); Latent nutritional factor (B1, B2, B9, C and fiber) |
Summary of findings
| Outcome | Effect | 95% CI | Certainty | Clinical relevance | Notes |
|---|---|---|---|---|---|
| Emotional distress (anxiety + depression — latent factor) | R2=0.19; path coefficients not reported with 95% CI | — | Low | — | 1 studies |
| Bacteroides abundance (mediator) | indirect mediation path; coefficients not reported with 95% CI | — | Low | — | 1 studies |
| Stool consistency — Bristol Stool Scale (mediator) | indirect mediation path; coefficients not reported with 95% CI | — | Low | — | 1 studies |
| Latent nutritional factor (B1, B2, B9, C and fiber) | CFA loadings significant; exact values and 95% CI not reported | — | Low | — | 1 studies |
Context
ALS involves gastrointestinal and emotional disturbances beyond motor dysfunction. Gut microbiota and diet are plausible mechanistic candidates, but causal evidence is absent in this population. With incidence of 1.4/100,000 in Spain and survival of 2–5 years, quality-of-life strategies carry clinical relevance.
What the study showed
Confirmatory factor analysis identified a single nutritional factor (B1, B2, B9, C, and fiber) with a significant inverse association with emotional distress. The structural equation model demonstrated direct and indirect effects of this factor on anxiety/depression, mediated by Bacteroides abundance and stool consistency. The model explained 19% of the variance in psychological distress (R²=0.19). Absolute effect sizes (path coefficients, 95% CI) were not reported in the available text.
How it was done
Cross-sectional study with 48 ALS patients from multiple Spanish regions. Dietary intake assessed by 24-h recall and food frequency questionnaire; anxiety and depression by validated scales aggregated into a latent factor via CFA; stool consistency by Bristol Scale; microbiota by fecal bacterial abundance quantification. No follow-up period (single time point).
Effect magnitude
The model explained 19% of the variance in emotional distress (R²=0.19). Individual effect sizes (standardized path coefficients, 95% CI) were not available in the provided text.
Risk of bias
Cross-sectional design precludes causal inference; a sample of 48 is insufficient for stable structural equation models (minimum rule: 10–20 observations per free parameter). No healthy control group. No risk-of-bias tool was applied (observational study; ROBINS-I would be appropriate). Reverse causality is uncontrolled: disease itself may alter diet and microbiota simultaneously.
What this study does NOT prove
This study does not prove causality between B vitamin/fiber intake and improvement of anxiety or depression in ALS. It is not generalizable to ALS populations outside Spain or to other disease stages and phenotypes.
In clinical practice
The data do not support recommending B vitamin or fiber supplementation as an intervention for anxiety/depression in ALS. Clinicians may incorporate structured nutritional assessment (B vitamins and fiber) and stool consistency monitoring as part of comprehensive care, without established therapeutic expectation for emotional outcomes.
Limitations
Cross-sectional design precludes causal inference; a sample of 48 is insufficient for stable structural equation models (minimum rule: 10–20 observations per free parameter). No healthy control group. No risk-of-bias tool was applied (observational study; ROBINS-I would be appropriate). Reverse causality is uncontrolled: disease itself may alter diet and microbiota simultaneously.
What is still missing
Randomized clinical trials with dietary intervention (or B vitamin + fiber supplementation) in ALS patients, using anxiety/depression and microbiota as pre-registered primary outcomes.
Technical appendix
Version history
- 1.0 · 2026-06-30 — Auto-generated under Evidence Standard v1.0