SupplementsSpecialtyDIM

DIM

Diindolylmethane, from broccoli and similar vegetables

A compound your body makes when you eat broccoli, sold for hormone balance. It clearly shifts how estrogen is processed. Whether that makes you feel better is less clear.

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A DIM capsule
Builds up
Weeks
In your body
Hours
Per 1 capsule
300 mg
30-day supply
$7.20One capsule a day, plus packing and delivery

What is dim?

When you chew broccoli, cabbage, kale or Brussels sprouts, one of their natural compounds breaks down, and your stomach acid then turns part of it into DIM, short for diindolylmethane. A capsule gives you far more than a plate of vegetables would.

DIM is popular for hormone balance, in part because of what it does to estrogen. Your body breaks estrogen down along different routes, and DIM seems to steer more of it toward a route often called the gentler one. Studies can measure this in urine.

Changing a number in urine isn't the same as feeling better or staying healthier, though. That's the gap the research hasn't crossed yet. Ours has 300 mg in each capsule.

What it does

  • Estrogen metabolismSupports how your body processes estrogen, in both men and women.
  • Hormone balanceCommonly used for this, though effects on symptoms are not well shown.
  • Vegetable compoundsProvides a compound your body makes from cruciferous vegetables.

These statements have not been evaluated by the FDA. This product is not intended to diagnose, treat, cure or prevent any disease.

The full guide · 15 min readDIM supplement: what it does, benefits for women and men, side effects and who should avoid itWhich form, how much, when to take it, and whether it's worth it, with the studies behind each answer.

What people take it for

How long it takes

Marker changes were looked for at about a month and later. Marker changes don't tell you whether you'll feel different, and that part hasn't been studied much.

DIM in your blood after a capsuleTypical pattern
Peaks within hours
Mostly cleared
Capsule24 hours
  1. HoursReaches your blood. Dark urine can show up, which is harmless
  2. About 4 weeksWhen studies start to look at estrogen markers
  3. After thatLong-term effects on health aren't well known

How long it stays in your body

In small studies, DIM reached the blood within hours and was mostly gone within about a day, so daily use keeps it around rather than building up.

What's in a capsule

One capsule holds 300 mg of DIM. Studies of estrogen markers used different amounts, and one found 75 mg a day wasn't enough to change the marker it measured. Forms also differ in how well they're absorbed.

What it did to estrogen, and why tamoxifen matters

Your body breaks down estrogen along a few routes. DIM pushes more of it toward one that produces a compound called 2-hydroxyestrone. In a 2024 look at urine tests from premenopausal women, DIM users had clear shifts in this pattern. Those are real, measurable changes, but nobody has shown they translate into fewer symptoms or better health.

The most important point is about tamoxifen, a medicine used for breast cancer. In a careful study of women taking it, DIM improved estrogen markers, but it also lowered tamoxifen's active forms in the blood, including endoxifen, the one that does most of the work. Researchers don't know if this makes tamoxifen work less well, but no one should risk that without their cancer doctor's advice. Please don't take DIM with tamoxifen on your own.

DIM can also affect how your liver clears other medicines, so anyone on regular medication should ask first. And if you have symptoms you put down to hormones, it's worth getting real numbers: estradiol, progesterone and thyroid tests can reveal what's happening.

Read the full guide to dim

What it interacts with

Goes well with

Side effects

  • Darker urine, which is harmless but can be surprising.
  • Headache and stomach upset, especially at higher amounts.
  • Changes in periods have been reported by some people.

Check first if

  • Pregnancy or breastfeeding: the label says not to use it.
  • Taking tamoxifen or a hormone-sensitive cancer history: talk to your cancer doctor first.
  • On birth control or hormone therapy: ask first.
  • Trying to conceive: talk to your doctor first, since it affects estrogen.
  • It's for adults only, as the label says. Check with a healthcare professional if you take any medication.

The blood tests that go with it

Work it out

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Supplementation

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These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure or prevent any disease.

Want it more precise? Get the app.

A page can only tell you about DIM. The app tells you about you: whether it fits, when to take it, and whether it's working.

  • Checked against your blood work and everything you already take
  • On your daily timeline, around your sleep, training and meals
  • Followed over time, so you can see what moved
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Questions

What is DIM good for?

It clearly changes how estrogen is processed. It's commonly used for hormone balance, but research on actual symptoms is thin.

Does DIM lower estrogen?

Not exactly. It's better described as shifting how estrogen is broken down. It can change estrogen markers in blood and urine.

How long does DIM take to work?

Marker changes were looked at from about a month. Whether and when you'd feel different isn't well studied.

What are the side effects?

Darker urine, which is harmless, plus headache and stomach upset in some people. Changes in periods have been reported too.

What does DIM interact with?

Tamoxifen is the big one. Birth control, hormone therapy and medicines cleared by the liver are also worth asking about.

Can men take DIM?

Yes, and men are sometimes interested in it because of estrogen. Research in men is limited, so testing before and after makes more sense than guessing.

Is it better to eat broccoli?

Eating cruciferous vegetables is a great idea for lots of reasons, but it gives much smaller amounts of DIM than a capsule.

Why is my urine dark on DIM?

It's a known and harmless effect of how your body clears it. If it worries you or doesn't go away, check with your doctor.

Sources
  1. Thomson CA et al. A randomized, placebo-controlled trial of diindolylmethane in patients taking tamoxifen. Breast Cancer Res Treat, 2017.
  2. Newman M et al. Exploring the impact of 3,3'-diindolylmethane on the urinary estrogen profile of premenopausal women. BMC Complement Med Ther, 2024.
  3. Godínez-Martínez E et al. Effectiveness of 3,3'-diindolylmethane supplements on the estrogen pathway and body fat. Nutr Cancer, 2023.
  4. Memorial Sloan Kettering Cancer Center. Diindolylmethane.

Written by LifeFrom from these sources, and not yet reviewed by a clinician. Talk to your doctor before starting a supplement.

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