Diindolylmethane (DIM) is a compound formed in the body during the digestion of indole-3-carbinol, which is found in cruciferous vegetables such as broccoli and Brussels sprouts. DIM is commonly used in dietary supplements marketed for "estrogen balance" or "hormonal health." Scientific interest in DIM is primarily due to its effects on estrogen metabolism. Specifically, DIM is believed to favor the production of 2-hydroxyestrone, a less potent estrogen metabolite, over 16α-hydroxyestrone, which is considered to have stronger estrogenic activity and has been linked to certain hormone-related cancers.

Several small-scale clinical trials and numerous animal and in vitro studies suggest that DIM can modulate estrogen metabolism and may have anti-proliferative effects on estrogen-sensitive tissues. Some research in women shows altered urinary estrogen metabolite ratios after DIM supplementation, and there is preliminary evidence for possible benefits in conditions like cervical dysplasia and recurrent respiratory papillomatosis. However, large, high-quality human studies in healthy populations are lacking, and the clinical significance of modifying estrogen metabolite ratios remains uncertain.

Overall, while there is a scientific rationale and early evidence for DIM's influence on estrogen metabolism, more robust clinical data are needed to confirm its efficacy and safety for supporting the estrogen body system.