Can a Broccoli Supplement Change How Estrogen Works After Menopause?

Study name: “The impact of 3,3′-diindolylmethane on estradiol and estrogen metabolism in postmenopausal women”. (Newman M.S, & Smeaton J., 2025)

What’s this about?
“3,3′-diindolylmethane,” or DIM, is a compound formed in the body after you eat cruciferous vegetables (think broccoli, cabbage, kale). Some alternative medicine and “wellness” practitioners promote DIM as a supplement, claiming benefits for hormone balance or even cancer prevention. This study asked if postmenopausal women are already using menopausal hormone therapy (MHT), specifically an estradiol patch, does taking DIM change how their estrogen is metabolized?

When and who?

The data came from laboratory results collected between January 1, 2016 and December 9, 2019 involving 1,458 lab results from postmenopausal women using a transdermal estradiol patch. Among those, 108 women reported that they were also taking a DIM supplement concurrently. 

As such, we have two groups: those on estradiol alone, and those on estradiol + DIM.

What Did They Find?

When comparing the two groups, the researchers saw that the women taking DIM had statistically significant changes in their urinary estrogen metabolite profiles. In other words, taking DIM altered how estrogen was being broken down and processed in the body. 

Specifically:

• DIM was linked to significant effects on 6 out of the 10 estrogen metabolites measured. 
• These included estrone (E1), estriol (E3), 2-hydroxyestrone (2-OHE1), 2-hydroxyestradiol (2-OHE2), 4-hydroxyestradiol (4-OHE2), and 16-hydroxyestrone (16-OHE1). 
• One metric often discussed in “estrogen metabolism balance” is the 2-OHE1/16-OHE1 ratio (a possible marker of more “protective” vs more “harmful” estrogen metabolites). DIM significantly changed that ratio.

Because estrogen (and its metabolites) influences many tissues including bones, experts caution that these changes might influence the clinical effects of hormone therapy: e.g. symptom relief, bone health, cardiovascular risk, etc.

Why Does This Matter?

Let’s pull back and see why this is important in real life:

1. Hormone therapy is delicate chemistry.
If you are on estrogen therapy, the way your body processes estrogen is key to its benefits, and its risks. Changing the metabolism (via supplements or other drugs) can theoretically blunt benefits or increase side effects.

2. Bone health hinges on estrogen.
After menopause, estrogen drops, and this accelerates bone loss and raises the risk of osteoporosis.This is one major reason some postmenopausal women use MHT, to help protect bones (in addition to alleviating symptoms). If DIM changes estrogen metabolism, it could alter how much “active estrogen effect” bone and other tissues actually see.

3. Supplements aren’t always benign when combined with medications.
Many women take “natural” or over-the-counter supplements without considering drug–supplement interactions. This study is a red flag, a supplement (DIM) shifted hormone metabolism in people already on MHT. But with important caveats:

• We don’t yet know whether these changes in estrogen metabolites are clinically meaningful (i.e., do they change outcomes like bone mineral density, symptom relief, fracture risk, or side effects?). Experts explicitly call for more research.
  
• This is observational / retrospective as it looks at existing lab data, not a prospective randomized trial. That limits conclusions about cause and effect.
  

What am I doing about it?

For now, I’m treating this study as an early signal rather than a final verdict. It’s fascinating to see how something as simple as a supplement derived from broccoli could shift estrogen metabolism, but we don’t yet know what that means for women’s health in the long run. Personally, I’m taking it as a reminder to be cautious about combining “natural” products with prescribed hormone therapy. I plan to keep an eye on future research to see if these metabolic changes translate into real-world effect on bone health, menopausal symptoms, or overall safety. And most importantly, I’m using this insight as motivation to have more open conversations with healthcare providers about supplements, medications, and the ways they can silently influence each other.

I have had doctors in the past recommend DIM to control estrogen metabolism, but I saw that it also drove my much needed estrogen down as well, so other doctors have pulled it off. In the meantime, I eat broccoli, broccoli sprouts, cauliflower and other cruciferous vegetables every day. If you’re not a fan of these vegetables, speak to your doctor about supplements that contain sulforaphane (the active component in broccoli), one popular brand is BroccoMax by Jarrows. 

Practical tips you can use now:

Here’s what women and clinicians might keep in mind:

• Always disclose supplements to your doctor.
  If you are taking (or thinking of taking) DIM or any supplement, tell your provider, especially if you’re on hormone therapy or medications.
• Be cautious about combining supplements with hormone therapy until more is known.
  Until there is stronger evidence, avoid layering on DIM (or similar compounds) without medical supervision.

• Focus on proven ways to support bone health.
  Supplements and hormone metabolism are interesting, but the basics matter:
  

• Calcium + Vitamin D – I am currently taking AlgaeCal* that includes all vitamins and minerals necessary for healthy bones.
• Weight-bearing and resistance exercise
  Healthy nutrition, limiting smoking, limiting excess alcohol
  Bone density screening (DEXA or REMS) when indicated
• Discuss hormone therapy (risks and benefits) with a specialist if you are considering or already using it
  

• If you do use DIM, monitor closely.
  • Get periodic lab checks (if your doctor agrees) for hormone/metabolite levels
  • Watch for changes in menopausal symptoms
  • Watch bone density over time
    
• Stay updated.
  As newer studies come out, the understanding might change. What’s cautious today might be better understood tomorrow.

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Reference: Newman M.S, & Smeaton J., (2025). The impact of 3,3′-diindolylmethane on estradiol and estrogen metabolism in postmenopausal women. PMC.