Skip to main content
Supplement ScienceSupplementScience

Indole-3-Carbinol (I3C) Dosage Guide

Evidence:Moderate
·

This content is for informational purposes only and does not constitute medical advice. Statements about dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease. Individual results may vary — consult your healthcare provider before starting any supplement. Full disclaimer

General Dosage

200-400mg I3C daily in divided doses

Maximum dose: 400mg daily; higher doses may cause GI side effects and unpredictable metabolite formation

Dosage Recommendations

General recommendation: 200-400mg I3C daily in divided doses

Timing: With meals in divided doses (e.g., 200mg twice daily); stomach acid is needed for conversion to active metabolites • Take with food for best absorption.

Dosage by Condition

Estrogen metabolism modulation
200-400mg daily in divided dosesModerate
HPV-related papillomatosis
200mg dailyModerate
Cervical health (CIN)
200-400mg dailyEmerging

Upper limit: 400mg daily; higher doses may cause GI side effects and unpredictable metabolite formation

Timing & Absorption

With meals in divided doses (e.g., 200mg twice daily); stomach acid is needed for conversion to active metabolites

Best taken with food for optimal absorption.

Full Indole-3-Carbinol (I3C) Guide

References

  1. ObservationalRosen CA, Bryson PC (1998). Indole-3-carbinol for recurrent respiratory papillomatosis: long-term results. Journal of Voice. DOI PubMed
  2. RCTBell MC, Crowley-Nowick P, Bradlow HL, et al. (2000). Placebo-controlled trial of indole-3-carbinol in the treatment of CIN. Gynecologic Oncology. DOI PubMed
  3. ObservationalReed GA, Arneson DW, Putnam WC, et al. (2006). Single-dose and multiple-dose administration of indole-3-carbinol to women: pharmacokinetics based on 3,3'-diindolylmethane. Cancer Epidemiology, Biomarkers & Prevention. DOI PubMed
  4. ReviewHigdon JV, Delage B, Williams DE, Dashwood RH (2007). Cruciferous vegetables and human cancer risk: epidemiologic evidence and mechanistic basis.. Pharmacological research. DOI PubMed