Reported Side Effects
While DIM is generally considered safe, some individuals may experience side effects, particularly when taking higher doses 1. Here's a breakdown of the reported side effects:
Gastrointestinal Issues:
The most common side effects are gastrointestinal in nature, including headache, nausea, vomiting, gas, and diarrhea 1. These issues may be more pronounced with higher doses of DIM 4. One study found that while doses up to 200 mg were generally well-tolerated, one participant experienced nausea, headache, and vomiting after taking a 300 mg dose 4.
Changes in Urine:
Some individuals taking DIM have reported darkening of the urine and changes in urine odor 5. Increasing water intake may help alleviate these effects 5.
Hormonal Effects:
DIM can influence estrogen levels, potentially leading to changes in the menstrual cycle. Some women using DIM have reported shorter menstrual cycles, longer periods, or more frequent periods 5.
Anti-androgen Effects:
Research on DIM's effects on testosterone levels has yielded conflicting findings. In some individuals, DIM appears to have an anti-testosterone effect, while bodybuilders have used it to try to boost testosterone levels 5. More research is needed to fully understand DIM's impact on testosterone.
Visual Impairment:
In one case report, a healthy female patient experienced visual impairment after taking excessive amounts of DIM daily for two months 6. The specific type of visual impairment reported was central serous chorioretinopathy, an idiopathic disease. Fortunately, the symptoms resolved eight weeks after discontinuing DIM use 6.
Other Side Effects:
Less common side effects associated with DIM include skin rashes 4.
Clinical Trials on DIM Side Effects
Several clinical trials have investigated the safety and side effects of DIM. Here are some key findings:
General Safety and Tolerability:
- A study involving 24 healthy individuals found that DIM doses up to 200 mg were well-tolerated, with only one person experiencing adverse effects at 300 mg 4.
Effects on Estrogen Metabolism:
- A trial involving postmenopausal women with a history of early-stage breast cancer found that 108 mg of DIM daily resulted in beneficial changes in estrogen levels without significant side effects 4.
- A study on women taking tamoxifen for breast cancer found that DIM increased the ratio of "good" to "bad" estrogen metabolites and increased sex hormone-binding globulin (SHBG) levels. However, it also reduced tamoxifen metabolites, raising concerns about potential interactions and reduced effectiveness of the medication 7. This interaction highlights the importance of consulting with a healthcare professional before taking DIM, especially if you are on any medications.
DIM and Thyroid Health:
- A pilot study on patients with thyroid proliferative disease (TPD) found that DIM modulated estrogen metabolism in a way consistent with anti-estrogenic activity 8. This suggests that DIM may have a protective effect against TPD by influencing estrogen's effects on the thyroid gland. The study also found that DIM was detectable in thyroid tissue, indicating that it can act directly on the thyroid gland 8.
