Ultra-Processed Food Consumption and Colorectal Cancer Risk: A Systematic Review and Two-Stage Mediation Meta-analysis
Bibliographic record
Abstract
Abstract Objective To evaluate the association between ultra-processed food (UPF) consumption and colorectal cancer (CRC) risk and to assess whether inflammatory bowel disease (IBD) mediates this relationship using a two-stage mediation meta-analysis. Design We conducted a systematic review and meta-analysis of cohort studies on (i) UPF intake and CRC, (ii) UPF intake and IBD, and (iii) IBD and CRC. Two reviewers independently screened records, extracted hazard ratios (HRs) or relative risks, and assessed study quality with the Newcastle–Ottawa Scale (NOS). Random-effects pooling (DerSimonian–Laird) generated summary HRs. A two-stage product-of-coefficients approach combined the pooled HR for UPF → IBD with that for IBD → CRC to estimate an indirect (mediated) effect; the direct effect was calculated by dividing the total UPF → CRC HR by the indirect HR. Heterogeneity, publication bias, risk of bias, and overall certainty (GRADE) were evaluated. Results Of 7,152 records screened, three comparisons from two prospective cohorts (≈ 404 000 participants) met criteria for the UPF → CRC analysis. High UPF consumption was not significantly associated with CRC risk (pooled HR = 1.14; 95 % CI 0.96–1.35; I 2 ≈ 45 %; Egger p = 0.60). Five cohorts informed the UPF → IBD analysis (pooled HR = 1.33; 95 % CI 1.13– 1.57; I 2 ≈ 76 %), and four comparisons from two registry-based studies informed the IBD → CRC analysis (pooled HR = 1.23; 95 % CI 0.96–1.57; I 2 ≈ 96 %). The two-stage mediation yielded an indirect HR of ≈ 1.64, but because both the IBD → CRC and the total UPF → CRC estimates included unity, mediation could not be confirmed; the implied direct effect (≈ 0.70) was also statistically uncertain. NOS scores ranged 6 – 9, indicating generally good quality. Under GRADE, certainty was low for UPF → CRC, moderate for UPF → IBD, and low for IBD → CRC; certainty for the mediation analysis was very low. Conclusion Current cohort evidence shows no statistically significant overall association between high ultra-processed food intake and colorectal cancer risk, although UPF consumption is consistently linked to higher IBD incidence. Any IBD-mediated CRC risk appears to be small and uncertain, and residual confounding cannot be excluded. Large prospective studies and intervention trials are needed to clarify the direct pathways through which UPFs may influence colorectal carcinogenesis.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.034 | 0.058 |
| Meta-epidemiology (narrow) | 0.004 | 0.002 |
| Meta-epidemiology (broad) | 0.021 | 0.059 |
| Bibliometrics | 0.006 | 0.006 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.003 |
| Open science | 0.004 | 0.002 |
| Research integrity | 0.003 | 0.002 |
| Insufficient payload (model declined to judge) | 0.004 | 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 source (direct Gemma or distilled Codex), 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".