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Benefits of Indole-3-Carbinol (I3C)

Evidence:Moderate
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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

Evidence-Based Benefits

  • Estrogen metabolism — I3C at 300-400mg daily has been shown to significantly increase the urinary 2:16α-OHE1 ratio, indicating enhanced 2-hydroxylation of estrogen; this shift is associated with potentially reduced proliferative signaling
  • Recurrent respiratory papillomatosis — Rosen et al. (1998) found that I3C at 200mg daily stopped or reduced papilloma growth in 33% of patients with HPV-related RRP, one of the few clinical applications with direct evidence
  • CYP1A1 induction — I3C and its metabolites are potent inducers of CYP1A1, a Phase I detoxification enzyme involved in estrogen 2-hydroxylation and xenobiotic metabolism
  • Cervical health — Bell et al. (2000) studied I3C for cervical intraepithelial neoplasia (CIN) and found regression in 50% of patients taking 200mg daily, compared to none in the placebo group

What the Research Says

Indole-3-Carbinol (I3C) is a compound derived from cruciferous vegetables and has been studied for its potential benefits in managing estrogen metabolism, HPV-related conditions, and cancer prevention. Rosen et al. (1998) conducted a study on recurrent respiratory papillomatosis (RRP), where 200mg of I3C daily led to remission or reduced disease progression in 63% of participants, with no worsening of symptoms. Bell et al. (2000) reported that in a randomized, placebo-controlled trial involving 30 women with cervical intraepithelial neoplasia (CIN II-III), I3C at doses of 200 and 400 mg/day significantly increased the rate of complete regression compared to placebo.

In terms of estrogen metabolism, I3C is known to influence the ratio of 2-hydroxyestrone (2-OHE1) to 16α-hydroxyestrone (16α-OHE1), though its effects are less consistent than those of DIM due to pH-dependent conversion kinetics. Reed et al. (2006) found that I3C administration in women resulted in detectable levels of its metabolite, DIM, with increasing doses up to 1,000 mg. However, the field has generally shifted toward recommending DIM over I3C for estrogen modulation due to DIM's more consistent bioavailability and activity as a primary active metabolite (Higdon et al., 2007).

Related Conditions

Hormonal Imbalance
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