Limited evidenceWomen's health

DIM (Diindolylmethane)

DIM reliably shifts estrogen metabolite ratios in the lab, but the largest clinical trial — 551 women with abnormal cervical cytology — found no effect on any real outcome. "Estrogen detox" marketing is far ahead of the data.

What the science says

Improves low-grade cervical cytological abnormalities Limited evidence
A double-blind randomized controlled trial gave 551 women with low-grade cervical cytological abnormalities 150 mg/day of DIM or placebo for 6 months and found no significant difference in cytology, colposcopic findings, or HPV clearance. This is the largest and cleanest DIM trial run, and it was flatly negative.
Benefits prostate cancer or prostatic intraepithelial neoplasia Limited evidence
A phase Ib placebo-controlled tissue biomarker trial of BR-DIM in men undergoing prostatectomy was designed to test tissue biomarker effects, not clinical outcomes, and its small size precludes efficacy conclusions. Other PIN studies were single-arm or open-label. Nothing here supports DIM as a cancer prevention or treatment agent.
Balances estrogen or clears "bad estrogen" Limited evidence
DIM does shift the urinary 2-hydroxyestrone to 16-alpha-hydroxyestrone ratio, which is the entire basis of the marketing story. That ratio is a biomarker whose prognostic meaning is contested, and no trial has shown that shifting it improves any clinical outcome — not breast cancer risk, not symptoms, not hormone-related complaints.
Treats hormonal acne, PMS or estrogen dominance Limited evidence
These high-volume marketing claims have no randomized controlled trial support at all. "Estrogen dominance" is not a recognized clinical diagnosis, and no DIM trial has used acne or PMS as an endpoint.

Dosage & safety

Studied doseThe main clinical trial used 150 mg/day of absorption-enhanced DIM for 6 months. Prostate biomarker studies have used considerably higher doses of BR-DIM. Commercial products typically supply 100-300 mg/day, often with black pepper extract or phosphatidylcholine for absorption — plain DIM is poorly absorbed, so dose comparisons across products are unreliable.

SafetyCommon effects are harmless but alarming-looking: dark or orange-brown urine, headache, nausea and gas. DIM induces CYP1A2 and modulates other cytochrome enzymes, so it can lower levels of drugs metabolized that way — clozapine, olanzapine, theophylline, tizanidine, and caffeine among them; it may also interact with tamoxifen metabolism, which matters for the population most likely to be sold it. Case reports describe hyponatremia and, at high doses, headache with vomiting. Avoid in pregnancy and breastfeeding. Anyone with a hormone-sensitive cancer should not self-prescribe DIM as an "estrogen detox" — talk to your oncologist first.

Scientific references

Effect of diindolylmethane supplementation on low-grade cervical cytological abnormalities: double-blind, randomised, controlled trial
Castañon A, Tristram A, Mesher D, Powell N, Beer H, Ashman S, Rieck G, Fielder H, Fiander A, Sasieni P — British Journal of Cancer, 2012
Phase Ib placebo-controlled, tissue biomarker trial of diindolylmethane (BR-DIMNG) in patients with prostate cancer who are undergoing prostatectomy
Gee JR, Saltzstein DR, Messing E, Kim K, Kolesar J, Huang W, Havighurst TC, Harris L, Wollmer BW, Jarrard D, House M, Parnes H, Bailey HH — European Journal of Cancer Prevention, 2016

Where to buy

Primaforce, DIM, 60 Capsules

View on iHerb

Referral link — this site may earn a commission on purchases.

Related in Women's health

Folic Acid (Vitamin B9) Strong evidence
Inositol (Myo-Inositol) Moderate evidence
Strontium Limited evidence
Soy Isoflavones Moderate evidence
Ipriflavone Limited evidence
Evening Primrose Oil Limited evidence