From the Guidelines
Diindolylmethane (DIM) supplements should be used cautiously due to potential contraindications and side effects, particularly in individuals with hormone-sensitive conditions or those taking medications metabolized by cytochrome P450 enzymes. DIM is generally contraindicated during pregnancy and breastfeeding due to insufficient safety data. People with hormone-sensitive conditions such as certain breast, uterine, or ovarian cancers should avoid DIM as it may affect estrogen metabolism.
Contraindications
- Pregnancy and breastfeeding: insufficient safety data
- Hormone-sensitive conditions: potential to affect estrogen metabolism
Side Effects
- Digestive issues: nausea, diarrhea, gas, and stomach cramps
- Headaches, dark urine, and increased urination
- Dizziness, skin rashes, and changes in menstrual cycles in women (at higher doses) These side effects typically occur at doses exceeding 200mg daily. The side effect profile relates to DIM's mechanism as a modulator of estrogen metabolism, affecting hormone pathways throughout the body. If side effects occur, reducing the dose or taking DIM with food may help minimize discomfort. Anyone experiencing severe reactions should discontinue use and consult a healthcare provider. According to the NCCN guidelines 1, close monitoring for signs of toxicity is recommended when co-administering DIM with other medications, particularly those metabolized by cytochrome P450 enzymes.
From the Research
Contraindications of DIM
- There are no direct contraindications mentioned in the provided studies, but it is suggested that postmenopausal women using a transdermal estradiol patch who choose to concurrently use a DIM supplement may have unexpected changes in their urinary estrogen profiles 2.
- The interaction between DIM and menopausal hormone therapy (MHT) may lead to changes in estrogen metabolism, which could potentially affect the effectiveness of MHT 2.
Side Effects of DIM
- The studies do not report any significant side effects of DIM, but it is noted that DIM may alter estrogen metabolism, which could lead to changes in urinary estrogen profiles 2, 3.
- One study found that DIM-treated subjects had a significant increase in levels of 2-hydroxyestrone (2-OHE1) and a nonsignificant increase of 47% in the 2-OHE1/16alpha-OHE1 ratio 4.
- Another study found that DIM supplementation was ineffective in increasing the Estrogen Metabolites (2-hydroxyestrogens: 16α-hydroxyestrone) Urine Ratio (EMUR) in premenopausal women, but it did lead to a significant decrease in body fat percentage 5.
- DIM has been found to undergo significant metabolism after oral dosing in humans, resulting in the formation of monohydroxylated and dihydroxylated metabolites, which may exhibit pharmacological activity 6.
Potential Interactions
- DIM may interact with menopausal hormone therapy (MHT), leading to changes in estrogen metabolism and potentially affecting the effectiveness of MHT 2.
- The metabolism of DIM may lead to the formation of metabolites that exhibit pharmacological activity, which could potentially interact with other drugs or supplements 6.