DIM and Testosterone: Does the Indole-3-Carbinol Lower Estrogen?

DIM (3,3′-diindonylmethane) is a naturally occurring byproduct of indole-3-carbinol (IC3), and IC3 itself is a byproduct of glucosinolate glucobrassicin, which is a compound found in all crusiferous vegetables, such as: broccoli, cauliflower, cabbage, brussel sprouts, kale, and the like.

There has been much discussion about DIM and its effects on the reproductive system. It’s claimed to work by reducing estrogen, while also promoting optimal free-testosterone levels via reduced SHBG (Sex Hormone Binding Globulin). Hence, why many bodybuilders and health conscious men do consume cruciferous vegetables in hopes of raising T and reducing estrogen.

If you’re active on the “natural hormone optimization” circles, you must have seen recommendations about DIM or IC3 multiple times already.

But the big question is – does DIM or straight on IC3 work as claimed – or are they both just two farts in the wind?

Indole-3-Carbinol, DIM, Estrogen and the Big T

indole-3-carbinol and testosterone levelsThe reason why most people use IC3 or DIM supplements, is to reduce their estrogen levels. There’s also some evidence that this could happen.

In particular, IC3 seems to help the liver to metabolize estrogen more efficiently (via upregulating the CYP1A2 enzyme)…

While also simultaneously converting strong estrogen molecules into less potent kind (via downregulation of the CYPB1B enzyme and upregulation of CYP1A2 enzyme). This should result in reduced estrogen levels and a more favorable estradiol/estrone ratio.

In a human study conducted nearly 20 years ago, 6-7 mg/kg of IC3 per day was able to significantly increase the clearance of estrogens via urine in both, men and women.

The supplement industry seems to have accepted the fact that it’s DIM (again DIM is just one of the many metabolites of IC3) that is responsible of these effects, and thus, extracted DIM would work just as well as IC3 or consumption of crusiferous vegetables…

…However, one animal study challenges this claim: The researchers from The University of Kansas Medical Center, found out that IC3 and tamoxifen (prescription estrogen receptor antagonist) both blocked estrogen (via different mechanisms), whereas extracted DIM had – even at the highest dose – ” no significant effects on any of the endpoints studied”.

Another study found out that isolated DIM might actually have some anti-androgenic effects in prostate cells, whereas IC3 isn’t known of having such effects.

All-in-all, the evidence points to the direction that IC3 supplements (affiliate link) or consumption of crusiferous vegetables, would be more beneficial for ones estrogen balance than supplementation with the metabolite, DIM.


I have used DIM supplements in the past and I think I have even recommended extracted DIM in this blog before. However, now that I have seen more studies about IC3, isolated DIM, and their effects, I must say that I’m more or less convinced that IC3 and cruciferous veggies are much better of a choice than DIM.

Given that DIM was noted of having anti-androgenic effects in one in-vitro study (only in tumor cells though), it’s possible that IC3 could have similar effects too, which is why you should be monitoring your hormones when taking it.

NOTE: The effective dose of IC3 when used for blocking estrogen in average sized male would land in between 400-800 mg’s of IC3 (see preferred supplement above), or about 2-3 pounds of raw broccoli.

DIM and Testosterone: Does the Indole-3-Carbinol Lower Estrogen? was last modified: January 25th, 2018 by Ali Kuoppala

Ali Kuoppala

Ali Kuoppala is the founder of Anabolic Men, and an Independent Researcher that has been credited with organizing the findings that have helped thousands of men reach hormonal balance.
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  1. Mindy Gugenheimer on 06/08/2015 at 01:05

    Hey Ali quick question, can I use hydrogen peroxide 3% percent as a mouthwash or is that bad for nitrines, also I eat a very clean diet, but I get morning breath thanks man

  2. William Lebek on 02/01/2016 at 03:02

    I’ve heard that consumption of raw cruciferous vegetables may suppress thyroid function, while common sense is that boiled vegetables are much less nutritious. What you think about it? Or what way would you prefer if you’d consume them on a daily basis?

    • Eli Zìháo on 22/01/2016 at 23:02

      Cruciferous vegetables contain goiterens that somewhat interfere with iodine absorbtion in the thyroid. I would just make sure youre getting more than enough iodine in your diet if your eating a good amount of these vegetables.

    • Gone Fishin on 25/06/2017 at 12:16

      You can reduce goitrogens by boiling or cooking.

    • KissedByPixies on 22/09/2017 at 13:53

      Goitrogens are also reduced by fermentation, consuming sauerkruat is safe for your thyroid and still gives you more raw nutrition, with the added benefit of good bacteria for your gut.

  3. William Lebek on 18/01/2016 at 16:12

    The supplement of IC-3 you recommend contains japanese knotweed, which itself have estrogenic effects on human body.

    Just a friendy tip so you can change it.

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