
DIM
Diindolylmethane (DIM) is a metabolite of Indole-3-carbinol (I3C), a compound found in cruciferous vegetables including broccoli, cabbage and cauliflower. It is the most studied of all I3C metabolites and is thought to be superior to IC3 as a chemoprotective compound for breast cancer and prostate cancer (3). DIM demonstrated anti-proliferative effects in animal and cancer cell models through various mechanisms.
In contrast to I3C which has been used in over a dozen clinical trials, few studies have been published using DIM. In one study, daily supplementation with DIM led to changes in estrogen metabolism in post menopausal women with a history of early stage breast cancer (4); DIM supplementation, did not, however, have any effects in women with cervical cell abnormalities (13).
DIM's effects have not been confirmed in cancer patients. Further studies are warranted.
Vegetables including broccoli, Brussels sprouts, cauliflower and cabbage (1)
Diindolylmethane (DIM), a metabolite of I3C, can induce apoptosis by modulating the expression of the Bax/Bcl-2. It demonstrated antiproliferative effects in animal and cancer cell models (1). It was also shown to inhibit invasion of normal tissue by cancer cells and to inhibit angiogenesis in cell culture models (5). Both DIM and I3C induce the activity of phase I and phase II enzymes involved in biotransformation and elimination of steroid hormones and carcinogens in vitro. Physiological concentrations of I3C and DIM induce cytochrome P450 enzymes in cancer cells in vitro. The increased CYP450 activity of these enzymes leads to increased metabolism of estrogen and degradation of estradiol needed for the growth of estrogen receptor-alpha positive cancer cells. DIM induces apoptosis in pancreatic cancer cells (6)and enhances the effect of erlotinib (7). In colon cancer and prostate cancer cells, DIM inhibits CDK activities (8) (9) and induces apoptosis by down regulating survivin (10) (11). DIM supplementation alters estrogen urinary metabolite profiles in women (4). DIM has androgen antagonistic effect (14). It inhibits prostate cancer cells proliferation and induces apoptosis through Akt activation, NF-KB DNA binding, and androgen receptor phosphorylation (15).
Diindolylmethane is a metabolic byproduct of I3C resulting from gastric acid conversion. On average 10-20% of I3C is metabolized to DIM (1). Following oral administration of I3C in mice, both I3C and DIM were detectable at mmol/L concentrations in organs and blood. I3C was quickly absorbed and cleared from tissues and blood in one hour while DIM had a slightly later peak concentration and was more persistent (2). An absorption-enhanced form of DIM was absorbed in a linear dose-dependent manner up to 200mg and a serum level of 104ng/ml was achieved. Higher doses did not result in increased serum concentration (12).
Theoretically, DIM and I3C can induce cytochrome P450 1 enzyme and may reduce serum concentration of medications that it metabolizes.
DIM supplementation has been shown to alter estrogen urinary metabolites in women (4).
Dalessandri KM, Firestone GL, Fitch MD, Bradlow HL, Bjeldanes LF. Pilot study: effect of 3,3'-diindolylmethane supplements on urinary hormone metabolites in postmenopausal women with a history of early-stage breast cancer. Nutr Cancer. 2004;50(2):161-167.
In a prospective placebo-controlled pilot study 19 post-menopausal women with a history of early stage breast cancer were randomized to receive 108mg DIM or placebo for thirty days. Urinary metabolite analysis was conducted for 2-hydroxyestrone (2OHE-1), 16-alpha hydroxyestrone (16alpha=OHE-1), DIM, estrone (E1), estradiol (E2), estriol (E3), 6beta-hydroxycortisol (6betaOHC) and cortisol. The treatment group demonstrated significant increases in levels of 2-OHE1 (P=0.020), DIM (P=0.045), and cortisol (P=0.039) and a non-significant increase in the 2-OHE1/16alpha-OHE1 ratio from 1.46 to2.14 (P=0.059). The results of this study demonstrate that DIM supplementation increases 2-hydroxylation of urinary estrogen metabolites. But whether this translates to reduced cancer risk has not been confirmed.
Bottomline: Diindolylmethane (DIM) may have anticancer effects, but this has not been studied in humans.
Diindolylmethane is a compound found in cruciferous vegetables including broccoli, cabbage, and cauliflower. It showed anticancer effects in laboratory and animal studies. However, human studies are limited.
In a prospective placebo-controlled study, 19 post-menopausal women with a history of early stage breast cancer were randomized to receive 108mg DIM or placebo for thirty days. Urinary metabolite analysis was conducted for 2-hydroxyestrone (2OHE-1), 16-alpha hydroxyestrone (16alpha=OHE-1), DIM, estrone (E1), estradiol (E2), estriol (E3), 6beta-hydroxycortisol (6betaOHC) and cortisol. The treatment group demonstrated significant increases in levels of 2-OHE1, DIM, and cortisol and a non-significant increase in the 2-OHE1/16alpha-OHE1 ratio. These results demonstrate that DIM supplementation increases 2-hydroxylation of urinary estrogen metabolites.
Although DIM (and I3C) were shown to alter estrogen urinary metabolite profiles in women, their effects on breast cancer risk are unknown.
Rash, arthralgia, nausea, vomiting, headache and hot flashes have been reported.