Diindolylmethane (DIM) for Cancer Prevention
There is only weak evidence that diindolylmethane (DIM) supplements help prevent cancer. The mechanism is plausible and DIM shifts estrogen-metabolism markers, but the largest, highest-quality trial showed no real benefit, and no study has measured actual cancer outcomes.
Why this grade7-layer evidence engine
The grade is Weak because all four randomized trials relied on surrogate or biomarker endpoints rather than cancer incidence or mortality, and no Phase 3 trial exists. The decisive signal is negative: the largest, high-quality RCT of oral BR-DIM (PMID 22075942, n=551) found no significant effect on cervical CIN2+ (8.8% vs 12.4%, RR 0.7, p=0.198), undercutting any optimistic read.
Supportive findings are thin and indirect. A small CIN trial (PMID 26693258, n=78) showed regression, but used a vaginal suppository rather than an oral supplement. Biomarker trials in breast (PMID 28560655, n=130) and prostate (PMID 26313229, n=45) confirmed DIM raises the 2/16α-hydroxyestrone ratio and SHBG, yet measured no clinical cancer outcome, and prostate-tissue uptake was inconsistent.
Authorities reinforce caution. The FDA treats BR-DIM as investigational, and the EU has not authorized DIM as a supplement. Mayo Clinic, Harvard, and the American Cancer Society do not recommend supplements for cancer prevention; guideline chemoprevention is limited to drugs like tamoxifen. Cleveland Clinic's positive language applies to DIM in whole cruciferous vegetables, not to pills.
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditable▸View the full decision path (audit trail)
- compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.513
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 無高階證據可裁決
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 1 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status