Pilot study: effect of 3,3'-diindolylmethane supplements on urinary hormone metabolites in postmenopausal women with a history of early-stage breast cancer

Dalessandri KM, Firestone GL, Fitch MD, Bradlow HL, Bjeldanes LF (2005) Nutrition and Cancer
Title and abstract of Pilot study: effect of 3,3'-diindolylmethane supplements on urinary hormone metabolites in postmenopausal women with a history of early-stage breast cancer

Key Takeaway

DIM supplementation significantly increases the 2-hydroxylation pathway of estrogen metabolism, shifting the ratio toward more protective metabolites.

Summary

This study examined the effects of DIM supplementation on estrogen metabolism in postmenopausal women.

Study design:

  • Postmenopausal women participants
  • DIM supplementation trial
  • Measured urinary estrogen metabolites
  • Assessed 2-OH:16-OH ratio changes

Key findings:

  • DIM significantly increased 2-hydroxylation
  • Improved 2-OH:16-OH ratio
  • Dose-dependent response observed
  • Well-tolerated with minimal side effects

Metabolite changes:

MeasureEffect
2-OH estroneIncreased
16-OH estroneDecreased or stable
2:16 ratioImproved

Mechanism:

  • DIM modulates CYP1A1 enzyme activity
  • Shifts estrogen toward 2-hydroxylation pathway
  • 2-OH metabolites are less estrogenic
  • May reduce estrogen-driven proliferation

Clinical implications:

  • DIM can favorably alter estrogen metabolism
  • Potential role in breast health
  • Achievable with supplementation
  • Consistent with cruciferous vegetable benefits

Safety:

  • Well-tolerated at study doses
  • No significant adverse effects
  • Darkened urine noted (expected, harmless)

Clinical significance:

Provides direct evidence that DIM supplementation can shift estrogen metabolism toward pathways associated with reduced estrogen-related disease risk.

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Source

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DOI: 10.1207/s15327914nc5002_5