Indole-3-carbinol (I3C) and estrogen metabolism

What 2 graded rows on indole-3-carbinol (i3c) agree on for estrogen metabolism, and where they differ. Counted side by side, never averaged.

Consensus finder Rows from the Indole-3-carbinol (I3C) page, reviewed Oct 21, 2026 How it decides

What the rows agree on

Each block and row is one graded row from the Indole-3-carbinol (I3C) page, with its PubMed record.

Supplement

Indole-3-carbinol (I3C) Choose another

2 rows · 117 people

They agree: both rows found an improvement.

No difference

Improved

Each block is one evidence row, sized by how many people it enrolled, with its grade inside.

From the rows

The best-graded row, grade C, is a randomized trial of 60 people (1994) and found an improvement.

The rows run from 57 to 60 people, published from 1994 to 1997: 2 single studies.

2 improved

Grade CUrinary estrogen-metabolite ratio · Improved
RCT · n 60 · 1994 · Women (three arms of 20)
400 mg/day (vs 20 g/day cellulose fibre or placebo) · 3 months
The urinary 2-hydroxyestrone:estriol ratio rose substantially by month 1 and stayed up for 3 months with I3C, but not with fibre or placebo; 3 of 20 women on I3C showed no change.
Row on the Indole-3-carbinol (I3C) page · PubMed 7827590 (opens PubMed)
Grade DUrinary estrogen-metabolite ratio by dose · Improved
RCT · n 57 · 1997 · Women at increased risk of breast cancer, mean age 47
50, 100, 200, 300 or 400 mg/day, or placebo · 4 weeks
The 2-hydroxyestrone:16-alpha-hydroxyestrone ratio rose more at 300 to 400 mg than with placebo or 50 to 200 mg (difference 0.48; 95% CI 0.30 to 0.67 at the median baseline ratio). No significant toxicity.
Row on the Indole-3-carbinol (I3C) page · PubMed 9589355 (opens PubMed)