Free entry from The Complete Supplement Guide
DIM (Diindolylmethane)
Graded Moderate · Hormonal Support & Vitality · free to read
DIM shifts estrogen metabolism toward the 2-hydroxyestrone pathway (considered more favorable) and away from 16-alpha-hydroxyestrone (considered less favorable), and this effect on urinary estrogen metabolite ratios is measurable and consistent across human trials.
The dose range, the form that actually absorbs, the purity red flags and what not to stack it with are in the guide.
Get The Complete Supplement Guide →Last reviewed September 2026
The verdict
Is DIM worth taking?
DIM shifts estrogen metabolism toward the 2-hydroxyestrone pathway (considered more favorable) and away from 16-alpha-hydroxyestrone (considered less favorable), and this effect on urinary estrogen metabolite ratios is measurable and consistent across human trials. What has not been established is whether this metabolite ratio shift translates into meaningful clinical outcomes in otherwise healthy people. DIM combined with tamoxifen reduces endoxifen (tamoxifen’s active metabolite), which is a critical safety flag for anyone using it alongside hormonal cancer treatment.
What it does
What DIM does in the body
Estrogen metabolism modification toward more favorable 2-hydroxy metabolites, aromatase modulation, and indirect testosterone support through reduced estrogen conversion in men. DIM is the primary active metabolite of indole-3-carbinol found in cruciferous vegetables, forming in the stomach during digestion of broccoli, cauliflower, and cabbage. It induces CYP1A1 and CYP1A2 enzymes that metabolize estrogen, shifting the 2-OHE1 to 16-alpha- OHE1 ratio in a direction considered more favorable in estrogen-sensitive tissue contexts.
The evidence
What the research actually shows
Moderate for the estrogen metabolite ratio effect specifically, weaker for downstream clinical outcomes. Multiple human trials confirm DIM supplementation shifts urinary estrogen metabolite profiles. A 2025 observational cohort study specifically found DIM altered estradiol and estrogen metabolite profiles in postmenopausal women on transdermal estradiol HRT, confirming real pharmacological activity. DIM reduced endoxifen levels in women taking tamoxifen in one RCT, a potentially serious drug interaction for that specific population.
Food first
Getting DIM from food
Broccoli, cauliflower, cabbage, Brussels sprouts, and kale are rich in glucosinolates that convert to indole-3- carbinol and subsequently to DIM during digestion. Regular consumption of cruciferous vegetables provides meaningful DIM from food. Lightly cooking rather than boiling preserves more glucosinolate content.
What the guide adds
The part that is not on this page
Everything above is the assessment. What the guide adds for DIM is the protocol:
- Optimal Form
- Dose Range
- Bioavailability
- Purity Red Flags
- Stack With / Avoid
147 entries across nine categories, every one graded against the clinical literature the same way.
About the author
Who graded this
Daniel Edlund is a Le Cordon Bleu-trained private chef in Los Angeles, a certified personal trainer and strength coach, and an internationally licensed massage therapist. Thirty years of strength training and fifteen years cooking in private estate kitchens. He is the author of The Complete Supplement Guide, which grades 147 entries against the clinical literature, and of The EASY Way to Organic Cooking, first published in 2013.
This page is information, not medical advice. Supplements interact with prescription medication and with each other, and the right answer depends on your own bloodwork and history. Talk to your doctor before starting anything, particularly if you are pregnant, nursing, managing a health condition, or already taking medication.
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