DIM (Diindolylmethane): Estrogen Studies and Safety
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DIM (Diindolylmethane): half-life, strengths and approval status

Amounts studied · Approval status · Half-life notes

What is DIM?

DIM (3,3'-diindolylmethane) is a compound formed in the body from indole-3-carbinol, found in cruciferous vegetables. As a supplement it is marketed for estrogen balance, and it has been studied for breast cancer prevention.

Also known as: diindolylmethane, 3,3'-diindolylmethane, BR-DIM.

Amounts studied

DIM has no intake value or upper limit, and there is no NIH fact sheet for it. A single-dose safety study (Reed 2008) tested 50 to 300 mg of an absorption-enhanced form (BR-DIM), and a 12-month trial (Thomson 2017) used 150 mg twice a day. These are study protocols, not a recommendation.

Approval status and how it is used

It is sold in the US as a dietary supplement. Under the 1994 dietary supplement law (DSHEA), FDA does not approve dietary supplements before they are marketed, and the maker, not FDA, is responsible for safety and labeling. There is no FDA-approved DIM drug.

In a 12-month randomized trial of 130 women taking tamoxifen for breast cancer (Thomson 2017), BR-DIM shifted estrogen metabolism (a higher urinary 2/16α-hydroxyestrone ratio) and raised SHBG compared with placebo, but did not change breast density. It also lowered blood levels of tamoxifen's active metabolites, including endoxifen; the authors said more research is needed to know whether that weakens tamoxifen's benefit. The trial abstract notes there is limited evidence of clinically relevant activity or long-term safety for regular DIM use.

In the single-dose study (Reed 2008), BR-DIM was well tolerated up to 200 mg; at 300 mg one of six people had mild nausea and headache and one vomited. The trials cited here were in women. If you take tamoxifen or an aromatase inhibitor, or are on TRT, ask your prescriber before using DIM.

DIM half-life and time to peak

  • Half-lifeNot listed
  • Time to peak (Tmax)Not listed

In a single-dose study (Reed 2008), DIM was detectable in blood in only one person at 50 mg; 100 mg of BR-DIM gave a mean peak of 32 ng/mL and 200 mg a mean peak of 104 ng/mL, while 300 mg did not raise the peak further (108 ng/mL). The abstract does not give a half-life or time to peak, so we do not list them.

How to track DIM in Dose Track

  1. Add DIM as a custom compound. Start typing its name and Dose Track fills in the details from its research library for you to check, and it sits next to everything else you take.
  2. Log each dose when you take it so your history shows exactly what you took and when.
  3. Set reminders on your own schedule, whether that is daily, weekly or every few days.
  4. Your log is stored on your phone and no account is needed. Data only leaves it for features you choose, like AI answers and lab reading.

How Dose Track handles peptides · Reconstitution calculator · Half-life calculator

AnastrozoleArimidex · half-life about 2 days Tamoxifen CitrateNolvadex, Soltamox · half-life about 6 days Testosterone CypionateDepo-Testosterone, Test C · half-life about 8 days

Frequently asked questions

What is the half-life of DIM?+
In a single-dose study (Reed 2008), DIM was detectable in blood in only one person at 50 mg; 100 mg of BR-DIM gave a mean peak of 32 ng/mL and 200 mg a mean peak of 104 ng/mL, while 300 mg did not raise the peak further (108 ng/mL). The abstract does not give a half-life or time to peak, so we do not list them.
Does DIM interact with tamoxifen?+
It may. In a 12-month trial (Thomson 2017), women taking tamoxifen plus DIM had lower blood levels of tamoxifen's active metabolites, including endoxifen, than those on placebo. The authors said further research is needed to know whether this reduces tamoxifen's benefit. Ask your oncologist before taking DIM.
Does DIM lower estrogen in men on TRT?+
The trials cited here were in women, not men on TRT. In those trials DIM changed how estrogen is broken down and raised SHBG. Estradiol on TRT is managed with your prescriber, based on blood tests.
Can I track DIM in Dose Track?+
Yes. DIM is in Dose Track's research library, so when you add it as a custom compound its details are filled in for you to check. You can then log each dose next to your other compounds, set reminders on your own schedule, and see your history next to your lab results. Your log is stored on your phone and no account is needed. Data only leaves it for features you choose, like AI answers and lab reading.

Sources

  1. Reed GA, et al. Single-dose pharmacokinetics and tolerability of absorption-enhanced 3,3'-diindolylmethane in healthy subjects. Cancer Epidemiol Biomarkers Prev. 2008;17(10):2619-2624.
  2. Thomson CA, et al. A randomized, placebo-controlled trial of diindolylmethane for breast cancer biomarker modulation in patients taking tamoxifen. Breast Cancer Res Treat. 2017;165(1):97-107.
  3. FDA. Questions and answers on dietary supplements.

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