Diindolylmethane: A Registered Dietitian Explains

Diindolylmethane (DIM) is a compound derived from the chemical indole-3-carbinol found in cruciferous vegetables like broccoli and Brussels sprouts. 

DIM plays a role in estrogen metabolism and has been studied for its role in reducing the risk of certain hormone-related cancers.

However, there is growing interest in DIM for its potential role in supporting hormone balance, and more DIM-containing supplements are becoming available. Still, additional research is needed to fully understand its role in hormonal balance. 

Does Diindolylmethane (DIM) Balance Hormones?

Some research indicates DIM influences estrogen metabolism. While the effects of that shift may have implications for cancer risk, its ability to address hormonal changes associated with perimenopause or menopause is unclear.  

• DIM and estrogen metabolism: DIM may influence estrogen metabolism, increasing the production of anti-inflammatory, anticancer-causing (anticarcinogenic) molecules. Specifically, DIM boosts levels of the weak estrogen, 2-hydroxyestrone, which may help prevent cancer. It also reduces 4- and 16a-hydroxyestrone, stronger estrogen byproducts that may promote cancer. This shift in the 2- and 16a-hydroxyestrone ratio due to DIM may be associated with lower cancer risk.
• DIM and sex hormone–binding globulin (SHBG): According to one study of women taking DIM and the anticancer medication tamoxifen, DIM increased sex hormone–binding globulin (SHBG) and improved estrogen metabolism. SHBG is a protein that influences how much sex hormone the body produces. High levels of SHBG are associated with a lower risk of breast cancer and death from breast cancer.

Further research is needed to fully understand DIM’s effects on estrogen metabolism and hormonal balance. However, its potential role in enhancing SHBG levels and shifting estrogen ratios may offer promising avenues for reducing cancer risk.

What Is DIM?

DIM is a plant compound with potential health benefits (phytonutrient).  

Cruciferous vegetables like cabbage, cauliflower, broccoli, and Brussels sprouts contain indole glucosinolates (also known as glucobrassicins). These are chemicals with potential health benefits. Once eaten, indole glucosinolates break down into indole-3-carbinol (I3C).  

Another series of reactions in the body converts I3C to DIM. Your gastrointestinal (GI) tract’s acidity facilitates this conversion. I3C is an unstable molecule, so the conversion to DIM happens relatively quickly.

Other Health Benefits of DIM

Researchers are still trying to fully understand DIM’s health benefits. Most research on DIM focuses on its potential anticancer benefits. However, as research evolves, more benefits of DIM may emerge. 

• Cancer prevention: DIM may protect against cancer by preventing the spread and growth of cancer cells. Emerging research points to a potential role of DIM in protecting against hormone-sensitive cancers like breast and prostate cancer. 
• Breast cancer recurrence: Some research shows a reduced risk of breast cancer recurrence with tamoxifen and a diet high in cruciferous vegetables. However, consuming enough cruciferous vegetables to get enough DIM through diet alone may be challenging.
• Metabolic health: Preliminary research in mice suggests that DIM may prevent fat cell accumulation. One human study observed slightly more weight and fat loss among women taking DIM than those taking a placebo. Still, more research is necessary to understand DIM’s role in weight loss and metabolic health.
• Endometriosis symptoms: DIM affects estrogen receptors, which play an important role in endometriosis. One study observed reduced pelvic pain and bleeding with DIM supplementation alongside the medication dienogest, a standard treatment for endometriosis.

Where Can I Find DIM?

DIM naturally exists in cruciferous vegetables. Cruciferous vegetables are rich in glucobrassicins, which can convert to DIM. 

The following cruciferous foods contain DIM:

Cooking cruciferous vegetables increases the amount of DIM in the food. 

DIM can also be found in supplements. Supplements contain DIM or I3C, which is converted to DIM once ingested. Encapsulated supplements may be more effective. Encapsulation protects the supplement until it reaches the stomach, where the acidic environment helps convert I3C to DIM.

How Much DIM Is Good for Me?

Dosages up to 300 milligrams (mg) appear safe and well tolerated among females. However, 200 mg is a more commonly recommended dosage.

DIM dosages may be larger for males than females. 

One preliminary clinical trial used 900 mg of DIM to improve prostatic intraepithelial neoplasia (PIN), a precursor to prostate cancer. Study participants taking 900 mg of DIM exhibited improved markers of PIN, leading researchers to suggest that DIM may be beneficial for reducing prostate cancer. Still, additional research is necessary.

Some supplements contain only DIM, while others use a proprietary blend that includes DIM. Studies evaluating DIM use 150 mg of DIM, so look for a supplement close to this amount. Many supplements do come in 200 mg doses.

Precautions

Few studies on DIM exist outside of cancer research. As always, and due to limited research, exercise caution when starting a DIM supplement.  

• Safety profile: Limited research exists on the safety of DIM, but so far, no serious adverse side effects have been found. Most research on DIM focuses on people currently with or who have a history of cancer, so it is unclear whether the safety of DIM would be different among healthy individuals. Use DIM with caution and under the guidance of a healthcare provider.
• Potential side effects: Commonly reported side effects include nausea, headache, and vomiting. Side effects may worsen with higher doses of DIM. Other side effects are possible. One study reported urine discoloration with DIM. Although DIM may interact with other medications, there are no known interactions currently.
• Considerations: Little is known about DIM’s effects on pregnancy. People who are pregnant, trying to become pregnant, or breastfeeding should avoid DIM. Individuals with hormone-related health conditions such as endometriosis or polycystic ovary syndrome (PCOS) should consult a healthcare provider before starting DIM.

Summary

Diindolylmethane is a compound derived from cruciferous vegetables that has potential health benefits. Although DIM influences estrogen metabolism and appears to have a role in reducing the risk of certain hormone-sensitive cancers, it does not balance hormones. 

Adding cruciferous vegetables to your diet provides numerous health benefits, including any associated with DIM. However, before starting a DIM supplement, please consult your healthcare provider to ensure it will be safe and effective for you.