The Dangers of DIM (diindolylmethane)
DIM, or diindolylmethane, is a compound your body naturally produces when you eat cruciferous vegetables like broccoli, kale, cauliflower, cabbage, and Brussels sprouts. It’s best known for supporting healthy estrogen metabolism and helping the body process estrogen down a more favorable detoxification pathway called the 2-OH pathway something you may recognize on a DUTCH hormone test as 2-hydroxyestrone (2-OH).
In a 2024 study, Precision Analytical researchers - who offer the DTUCH hormone test- showed that DIM produces significant alterations across the urinary estrogen profile in a way that lowers total estrogen levels and supports healthier estrogen metabolism in premenopausal women. (¹ Newman et al., 2024)
For example, if you’ve done a DUTCH hormone test, you’d see which pathway you favor when you metabolize estrogen, suggesting whether you’re at an increased risk for cancer-driven diseases or if you’re “metabolizing” these hormones in a more favorable manner. This could bring great comfort to you if cancer runs in your family.
A pilot study published in Thyroid found that DIM supplementation increased the favorable 2-hydroxyestrone to 16α-hydroxyestrone ratio, suggesting that DIM may help support healthier estrogen metabolism and potentially reduce estrogen-driven tissue proliferation (Rajoria et al., 2011). (Michnovicz et al., 1997)
This is why many women notice improvements in:
PMS symptoms
Breast tenderness
Bloating
Heavy periods and blood clots
Hormonal acne
DIM Supplement Side Effects
One thing I’ve noticed with clients — and experienced personally — is that some women feel emotionally “flat,” low, or unmotivated when taking DIM every single day, especially during perimenopause or postmenopause.
Dr. Ben Lynch states, "Estrogen and dopamine are closely connected. When estrogen drops too low, dopamine signaling can also decline.”
Which may affect:
Mood- feeling so sad
Motivation - not wanting to do anything
Focus
Memory - where did I put my keys
Pleasure
Energy
This does not necessarily mean DIM is “bad.” It may simply mean your body needs to cycle this supplement, and don’t take it every day.
When to Take DIM or I3C (Indole-3-Carbinol supplement)
Many women benefit from using DIM or I3C during higher-estrogen phases of the cycle — typically around ovulation, which often falls between days 12–16 of a 28-day cycle.
Estrogen naturally rises before ovulation, and for some women, this can contribute to:
PMS
Breast tenderness
Irritability
Anxiety
Mood swings
Water retention
To summarize: ONLY take DIM when you feel high estrogen, usually on days 12-16 - then STOP.
Supporting Dopamine & Serotonin Naturally
During lower-estrogen phases — after ovulation, during perimenopause, or postmenopause — some women benefit from supporting healthy dopamine and serotonin levels.
===If you took too much DIM and are noticing you're feeling sad, OR it's a time of the month when you have low estrogen, you can take one of these supplements below to raise your serotonin levels.
5-HTP (for serotonin support): 5-HTP is a precursor to serotonin and has been studied for its ability to increase serotonin production in the brain. (Turner et al., 2021)
Some women also use products like Dopamine Nutrients (L-tyrosine and more) or Brain Nutrients (Seeking Health), particularly when experiencing poor focus, low motivation, or brain fog during hormonal fluctuations.
Nutritionist Trudy Scott’s work on amino acids and mood support has also helped many women better understand the connection between neurotransmitters, hormones, anxiety, and PMS.
Important: More DIM Is Not Always Better
If you take too much DIM, or take it continuously without paying attention to your cycle, you may accidentally lower estrogen too much for your body.
This is why blindly taking supplements every single day without tracking symptoms can backfire.
Your body’s hormonal needs change throughout the month.
Instead of forcing the body into the same protocol daily, it’s often more supportive to:
Start Tracking Your Cycle
Even in perimenopause, cycle tracking can reveal powerful patterns.
I recommend using a written calendar — not just an app — so you can physically observe:
Mood changes - are you sad? angry? or crying?
Sleep patterns - insomnia usually occurs days 14-28 with low progesterone
Cravings
Ovulation symptoms
PMS timing
Energy fluctuations
Tracking your cycle helps you learn what your body needs and when.
xo
Tara
P. S. Have you tried DIM? What was your experience? Let me know in the comment area below.
Resources
¹ Newman, M., Smeaton, J. Exploring the impact of 3,3’-diindolylmethane on the urinary estrogen profile of premenopausal women. BMC Complement Med Ther 24, 405 (2024). https://doi.org/10.1186/s12906-024-04708-7 ↩
https://dutchtest.com/articles/dims-effects-on-urinary-estrogen-mht↩
Turner EH, Loftis JM, Blackwell AD. Serotonin a la carte: supplementation with the serotonin precursor 5-hydroxytryptophan. Pharmacol Ther. 2006 ↩ Mar;109(3):325-38. doi: 10.1016/j.pharmthera.2005.06.004. Epub 2005 Jul 14. PMID: 16023217. ↩
Read more about amino acids here: https://www.taragregorio.com/blog/5-amino-acids-for-postpartum-anxiety ↩
