What is DIM (diindolylmethane)? A plain guide

DIM (diindolylmethane) is a compound your body forms from indole-3-carbinol, a substance found in broccoli, cabbage, kale, and Brussels sprouts, when stomach acid breaks that substance down. Supplements skip that food-digestion step and deliver DIM directly, usually as a capsule standardized to a set amount.

What DIM actually is

Cruciferous vegetables contain compounds called glucosinolates. When you chew and digest them, an enzyme called myrosinase converts one of those glucosinolates into indole-3-carbinol (I3C). I3C is unstable in the acidic environment of the stomach, and under those conditions it converts into a handful of related compounds — DIM is the main one, alongside smaller amounts of others (PMID 26651978). So DIM isn't itself present in a raw vegetable in any meaningful amount; it's a downstream product of digestion, or, in a supplement, a compound manufactured and delivered directly so the body doesn't have to make it from I3C first.

Where it comes from

Because DIM depends on how much I3C-precursor you eat and how your digestion handles it, the amount your body produces from food varies by vegetable and by person. A 2014 randomized crossover trial gave 25 people 50 g a day of either raw Brussels sprouts (high in the glucosinolate that becomes I3C) or raw cabbage (lower in it) for three days each, then measured DIM in their urine. Urinary DIM was consistently and significantly higher after the Brussels sprouts (PMID 24357105) — a direct demonstration that how much of this compound your body makes from food depends on which vegetable, and how much of it, you actually eat.

How the body handles it

For years, pharmacokinetic studies reported that DIM passed through the body largely unchanged after oral dosing. A 2021 study complicated that picture: 7 healthy adults took about 90.6 mg of DIM a day (two capsules of an absorption-enhanced formulation) every evening for a week, then had blood and urine tracked for 48 hours after the last dose. Researchers found DIM was extensively metabolized into several other compounds — two single-hydroxylated forms and one double-hydroxylated form, plus sulfate and glucuronide conjugates of each — in both plasma and urine. One of those metabolites was actually more active than DIM itself in a lab test of a specific cell-signaling pathway (PMID 34035125). What that means practically is still being worked out; the point for a supplement label is that "DIM" isn't necessarily the only or even the most active compound circulating after you take it.

Forms it's sold in

Nearly all DIM on the market is a capsule or tablet, standardized to a specific milligram amount of DIM rather than to the whole vegetable extract it could theoretically be derived from. Most commercial DIM is manufactured synthetically to that standardized purity rather than extracted from vegetables — the natural concentration in food is too low to make extraction practical at commercial scale. Because DIM itself absorbs poorly on its own, many products use some kind of absorption-enhancing delivery — a micronized particle size, an emulsified or oil-based capsule, or a paired ingredient like black pepper extract — to improve how much reaches the bloodstream. The 2021 pharmacokinetics study above used exactly this kind of formulation, which is part of why it was able to detect DIM and its metabolites in blood and urine at all (PMID 34035125). See how to choose a good DIM for what to check on a specific label.

Why people take it

DIM is popularly marketed around how the body processes estrogen — the idea that shifting which estrogen-related compounds circulate could support hormone balance, skin, or weight goals. That's a proposed mechanism, and it's a separate question from whether it's actually been shown to do any of those things in people at the doses sold. The honest answer is mixed and, in several areas, thin — covered in full in DIM benefits: what the research does and doesn't show, including what's been tested (and not tested) around fibroids, PCOS, menopause, acne, and men's health specifically.

Questions people ask

Does DIM change urine color, or make your pee orange?

We didn't find a study that measured urine color as an outcome. What is documented is that DIM and several of its metabolites are excreted in urine (PMID 34035125), so it's biologically plausible that a concentrated dose could tint urine, the way some vitamins and foods do — but that's an inference, not a tested finding. A color change alone isn't a known safety signal; new or unexplained urine changes alongside other symptoms are worth mentioning to a doctor.

What is DIM supplement made of?

The active ingredient is manufactured DIM, standardized to a stated milligram amount, usually combined with a capsule shell and, often, an absorption-enhancing ingredient or delivery technology. Check the supplement facts panel and "other ingredients" line on any specific product for the full list — see how to choose a good DIM.

DIM supplement vs indole-3-carbinol (I3C) — what's the difference?

I3C is the compound found more directly in cruciferous vegetables; DIM is what I3C converts into under acidic conditions, including in your stomach. A DIM supplement delivers that end-product directly, skipping the conversion step. The two aren't interchangeable in research either: animal studies have found I3C and DIM affect liver drug-metabolizing enzymes differently, which matters for DIM and medications: what to check.

What is "DIM SGS" or other named DIM blends?

Manufacturers sometimes pair DIM with other ingredients — a soy-derived compound, an absorption enhancer, or a specific delivery technology — and give the combination its own name on the label. A branded blend name doesn't tell you what's inside or how much; use the checklist in how to choose a good DIM to evaluate any specific product on its own label facts.

How does DIM work?

The leading proposed mechanism involves how DIM affects liver enzymes that metabolize estrogen, shifting the balance of estrogen-related compounds your body produces. That's been demonstrated in lab and animal research and, to some extent, in small human trials measuring urinary metabolites — but a shifted metabolite ratio isn't the same as a proven downstream health benefit. See DIM benefits: what the research does and doesn't show for what's actually been tested in people.

Related reading: DIM benefits: what the research does and doesn't show, how much DIM should you take a day?, and how to choose a good DIM.