DIM
TL;DR
Natural compound formed when you digest broccoli, cauliflower, and other cruciferous vegetables
Supports healthy estrogen metabolism by promoting 'good' vs 'bad' estrogen metabolites
May help with hormonal acne, PMS symptoms, and estrogen dominance issues
Can affect thyroid function - avoid if you have thyroid problems or iodine deficiency
Limited human studies - mostly mechanistic research and small trials
Best for: hormonal balance support, those who don't eat cruciferous vegetables regularly
What it is
DIM (diindolylmethane) is a compound naturally formed in your stomach when you eat cruciferous vegetables like broccoli, Brussels sprouts, and cabbage. When these vegetables are chewed and exposed to stomach acid, their indole-3-carbinol converts to DIM and related compounds.
DIM influences estrogen metabolism by promoting the production of 2-hydroxyestrone (considered a 'good' estrogen metabolite) over 16-alpha-hydroxyestrone (potentially problematic). This shift in estrogen metabolism is thought to support hormonal balance and may reduce risks associated with estrogen dominance.
What the research says
DIM on Amazon
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Safety
DIM is generally safe for most people at typical doses of 100-300mg daily, as it's derived from common food sources. However, some people experience side effects including headaches, nausea, gas, and changes in urine color (darkening).
The main concern is thyroid function. Cruciferous compounds can interfere with iodine uptake and thyroid hormone production, particularly in people with existing thyroid conditions or iodine deficiency. High doses may worsen hypothyroidism or interfere with thyroid medications.
Interactions
• Estrogen-based medications - May alter estrogen levels and effects • Tamoxifen - Could theoretically interfere with this breast cancer treatment • Thyroid medications - Cruciferous compounds may affect absorption and thyroid function • Blood thinners - Limited data suggests possible interaction • CYP1A1/1A2 enzymes - DIM may induce these liver enzymes, affecting drug metabolism
Dosing
General Hormonal Support 100-200mg daily with meals. Start with lower doses to assess tolerance.
Hormonal Acne/PMS 200-300mg daily, often taken cyclically (e.g., second half of menstrual cycle for PMS).
Enhanced Absorption Look for formulations with piperine (black pepper extract) or phosphatidylcholine for better absorption. Take with fat-containing meals.
Cost
DIM supplements typically cost $20-35 per month for quality products. Enhanced absorption formulations and higher potency products are at the upper end of this range. While more expensive than basic vitamins, it's reasonably priced compared to other specialty hormonal support supplements.
The bottom line
DIM has a plausible mechanism for supporting healthy estrogen metabolism, but human research is still limited. It's worth considering if you have signs of estrogen dominance (irregular periods, hormonal acne, PMS) and don't regularly eat cruciferous vegetables. However, avoid if you have thyroid issues, and start with lower doses to gauge tolerance. The effects are subtle and take time to manifest - this isn't a quick fix for hormonal problems.
References
- Banerjee S, Kong D, Wang Z, et al. 3,3'-Diindolylmethane enhances chemosensitivity of multiple chemotherapeutic agents in pancreatic cancer. Cancer Res. 2009;69(13):5592-600.
- Thomson CA, Ho E, Strom MB. Chemopreventive properties of 3,3'-diindolylmethane in breast cancer: evidence from experimental and human studies. Nutr Rev. 2016;74(7):432-43.
Sources for this page include published meta-analyses, systematic reviews, and NIH dietary supplement fact sheets. All claims reflect the evidence as of early 2026.
This is not medical advice. Consult your healthcare provider before starting any supplement, especially if you take medications.