DIM (diindolylmethane) shifts estrogen metabolism in human studies, mostly in women. What it does, the doses studied (100-300 mg), the evidence in men and the cautions.
DIM (diindolylmethane) forms when you digest cruciferous vegetables. At 100 to 300 mg a day it shifts estrogen metabolism toward 2-hydroxyestrone in human studies, mostly in women. We found no human trial showing DIM raises testosterone or improves symptoms in men, and it can raise SHBG, a protein that binds testosterone.
DIM (diindolylmethane) is a compound formed in the gut from indole-3-carbinol (I3C), which is found in cruciferous vegetables including broccoli, Brussels sprouts and cauliflower. At supplement doses, DIM affects liver enzymes involved in breaking down estrogen.
The liver processes estrogen through several pathways. Two of the resulting metabolites are 2-hydroxyestrone, often described as the more favorable one, and 16α-hydroxyestrone. In human studies, mostly in women, DIM raised the ratio of 2-hydroxyestrone to 16α-hydroxyestrone. Whether this changes health outcomes hasn't been established.
As men age and gain body fat, more testosterone is converted to estrogen by the aromatase enzyme. DIM is marketed to men on the idea that it helps clear estrogen, but we found no human trial showing it raises testosterone or improves symptoms in men. In the largest DIM trial (130 women taking tamoxifen, 150 mg twice daily for a year), DIM also raised SHBG, which binds testosterone and can lower the free fraction, and it lowered levels of active tamoxifen metabolites.
Human DIM studies have mostly used 100 to 300 mg a day, and more isn't necessarily better. In a 2008 dose study, single doses up to 200 mg were well tolerated, while 300 mg added side effects such as nausea and headache without raising blood levels. DIM3X provides 200 mg a day, within the studied range and similar to many competitors.