DIM

3,3'-Diindolylmethane is a dimeric indole with the formula C17H14N2. It arises when indole-3-carbinol, the breakdown product of the plant compound glucobrassicin, undergoes acid-catalyzed condensation in the stomach; DIM is the predominant product of this reaction and is used as a urinary marker of dietary cruciferous vegetable intake ^[1][2]. The parent glucosinolate is released when cruciferous vegetables are cut or chewed and the enzyme myrosinase acts on them.

Although DIM originates from ordinary foods, the amounts used in research and supplements far exceed what a normal diet provides; producing supplement-level quantities from food would require eating kilogram amounts of Brussels sprouts, which is why concentrated indole-3-carbinol and DIM preparations are studied instead ^[1]. Both indole-3-carbinol and DIM shift the way the body processes estrogen, increasing 2-hydroxylation and thereby altering the balance among estrogen metabolites, an effect that underlies much of the interest in breast and prostate applications ^[1][2].

At the molecular level, the best-characterized action of DIM is modulation of the aryl hydrocarbon receptor, a transcription factor that regulates drug-metabolizing enzymes and that engages in crosstalk with estrogen receptor and Nrf2 signaling ^[1][3]. In cultured cancer cells DIM has additionally been reported to induce cell cycle arrest and apoptosis and to interfere with epithelial-mesenchymal transition, a process linked to tumor spread, through signaling pathways such as TGF-beta and Notch ^[4].

DIM and its parent compound are under laboratory and early clinical investigation as chemopreventive agents, with most attention directed at breast and prostate cancer; they have shown activity in preclinical models and have been generally well tolerated with few adverse effects in the clinical trials conducted so far ^[1]. DIM is not an approved medicine. It is sold over the counter as capsules and tablets, frequently combined with absorption enhancers because the pure compound is poorly soluble in water.

DIM is generally well tolerated; higher doses can cause headache, GI upset, darker urine, and occasionally changes in menstrual timing. Because it shifts hormone metabolism it should be used cautiously alongside hormonal medications or in hormone-sensitive conditions. Very high doses have been linked to more noticeable side effects, so more isn't better.