tuneTypical Dose
Small neoplasia trials used 200 to 400 mg daily
Compound
Indole-3-Carbinol
Indole-3-carbinol
Evidence TierCWADA NOT PROHIBITED
watchEffect Window
Studied effects were assessed after 12 weeks to 6 months.
check_circleCompliance
WADA NOT PROHIBITED
Overview
Clinical Summary
Indole-3-carbinol has niche evidence in cervical and vulvar intraepithelial neoplasia, but it should not be marketed as a general estrogen-metabolism or cancer-prevention supplement.
Indole-3-carbinol is usually sold as a hormone-metabolism supplement, but its meaningful human evidence is much narrower. Small older trials found regression or symptom-improvement signals in cervical and vulvar intraepithelial neoplasia. Those studies are interesting but small, condition specific, and have not been followed by modern confirmatory randomized trials. They are not a basis for broad self-treatment or generalized cancer-prevention claims.
I3C and its downstream metabolites are usually discussed for effects on estrogen metabolism and aryl-hydrocarbon-receptor signaling. Those mechanisms are plausible but should not be overextended beyond the limited human interventional data.
Outcomes
What This Is Expected To Influence
Primary Outcomes
- Possible regression signal in cervical intraepithelial neoplasia
Secondary Outcomes
- Possible symptom and lesion-size improvement in vulvar intraepithelial neoplasia
Safety
Contraindications and Interactions
Contraindications
- Pregnancy
Side effects
- GI upset
Interactions
- Hormone-directed therapy
Avoid if
- You are self-treating suspected dysplasia instead of using standard care
Evidence
Study-level References
i3c-SRC-001Randomized controlled trial
Sourceopen_in_newBell MC, et al. Placebo-controlled trial of indole-3-carbinol in the treatment of CIN. Gynecol Oncol. 2000. PMID:10926790.
Population: Women with biopsy-proven CIN II-III.
Dose protocol: 200 or 400 mg daily for 12 weeks
Key findings: Some complete regression versus none on placebo.
Notes: Best direct CIN trial.
Paper content
This small trial is the strongest direct human efficacy signal for I3C. It showed histologic regression in some women with CIN II-III compared with none on placebo.
i3c-SRC-002Randomized phase II trial
Sourceopen_in_newNaik R, et al. A randomized phase II trial of indole-3-carbinol in the treatment of vulvar intraepithelial neoplasia. Int J Gynecol Cancer. 2006. doi:10.1111/j.1525-1438.2006.00398.x. PMID:16681761.
Population: Women with high-grade vulvar intraepithelial neoplasia.
Dose protocol: 200 or 400 mg daily for 6 months
Key findings: Improved symptoms and lesion size in high-grade VIN.
Notes: Useful secondary condition-specific evidence.
Paper content
This small VIN trial supports a limited signal for symptom and lesion-size improvement with I3C, but it does not show clear histologic reversal.