How much DIM (diindolylmethane) should you take a day?

There's no official recommended dose of DIM, unlike vitamins and minerals with a government-set intake range. The one dose we can point to from a general-population human study is about 90.6 mg a day; beyond that, most specific DIM doses in the research literature come from trials in particular health-research populations, not from testing what works best for a general audience.

What's actually been measured in a general population

A 2021 pharmacokinetics study gave 7 healthy adults, on a diet restricted in cruciferous vegetables, two 150-mg capsules of an absorption-enhanced DIM formulation each evening for a week — 45.3 mg of DIM per capsule, 90.6 mg total per day. Researchers tracked DIM and its metabolites in blood and urine for 48 hours after the final dose (PMID 34035125). That study measured how the body processes DIM at that dose; it wasn't designed to test whether 90.6 mg does more or less than another amount for any specific outcome.

For scale, a 2014 trial found that eating 50 g a day of raw Brussels sprouts — a vegetable naturally higher in DIM's dietary precursor — produced significantly more DIM in urine than eating the same amount of cabbage (PMID 24357105). That's a dietary exposure from food, not a supplement dose, but it illustrates that the amount of DIM your body handles from food alone varies quite a bit depending on what you eat, well before a supplement enters the picture.

Why most published doses don't transfer directly

Outside of the study above, most human trials that used a specific, well-documented DIM dose did so in women or men who were part of hormone-related health research — testing DIM's effect on lab and tissue markers in those specific groups, not in the general population and not for the reasons DIM is most often sold. Those doses ranged from about 75 mg to 450 mg a day, over periods from 30 days to a year, and what each trial measured (and found, or didn't) is covered in full in DIM benefits: what the research does and doesn't show. A number that worked, or didn't, in one of those specific research contexts isn't automatically the right number for a different reason for taking DIM.

Is there a maximum, or a dose that's "too much"?

No government body has set an upper intake level for DIM the way one exists for magnesium or vitamin D. No trial we reviewed compared different doses of DIM head-to-head to find a point of diminishing returns or increased risk, so there's no research-based number to point to as a ceiling. A higher milligram number on a label reflects what the manufacturer chose to include, not a tested "more effective" amount. See DIM side effects for what's been reported, including at higher, self-directed doses.

Questions people ask

How much DIM supplement should I take a day?

There's no single research-backed number for a general population. Following the directions on whatever product you're using, and checking with a pharmacist or doctor if you're unsure, is more reliable than a milligram figure pulled from a trial run in a different population for a different reason.

Is 200 mg, 300 mg, or 400 mg of DIM too much?

None of these has been tested against another dose to establish a "right" amount, so there's no research basis to call any of them too much or too little in isolation. They sit within the general range — roughly 75 to 450 mg a day — that's appeared across the human research we reviewed, in specific research contexts covered in DIM benefits: what the research does and doesn't show.

How much DIM supplement is safe to take daily?

No formal safety ceiling has been established in the research we reviewed. See DIM side effects and who should not take DIM? for documented reports, including at higher, self-directed doses — that's a better guide to caution than any single "safe" number.

Can you overdose on DIM?

No formal overdose threshold exists in the research reviewed here. A published case report describes a serious reaction after two months of excessive, self-directed daily use (more in DIM side effects) — a reason to follow a product's own label directions rather than exceed them on your own.

How much DIM for dogs, or by body weight?

This page and its citations cover DIM as a human supplement. None of the research here was conducted in animals, and scaling a human dose down for a pet by body weight isn't something a veterinarian would recommend doing without guidance. Ask a veterinarian before giving any human supplement to an animal.

Related reading: what is DIM (diindolylmethane)? A plain guide, when is the best time to take DIM?, and DIM benefits: what the research does and doesn't show.