# The Impact of Sulforapahane on Sex-Specific Conditions and Hormone Balance: A Comprehensive Review
## 8 Afterword: I3C and DIM  
Cruciferous vegetables contain a wide array of glucosinolates--some 120 different but closely related compounds. Glucoraphanin is the predominant glucosinolate in broccoli sprouts and seeds, but, as the plant develops and matures, the composition of these glucosinolates (defensive compounds for the plants) changes, and in market stage broccoli, there is a preponderance of indole glucosinolates. It may be reasonable to assume that the presence of both glucoraphanin and indole glucosinolates in a plant matrix may be beneficial to humans, because the epidemiologic evidence for the benefit of broccoli to provide protection against disease is very strong [1,185]. Indole glucosinolates are unique among the glucosinolates in that they do not form stable isothicyanates upon enzymatic treatment with myrosinase, but rather, form indole-3-carbonol (I3C) and its biologically active dimer (3,3'-dinidylmethane, di-indolyl methane, or DIM). I3C and DIM are thus often referred to together in both the scientific and general lit erature (e.g., I3C/DIM). As detailed in our earliest work on broccoli sprouts [5], \"hydrolysis of indole glucosinolates by myrosinase gives rise to bifunctional inducers, such as indole-3-carbinol and indole-3-nitrile, and to condensation products, such as 3,3\({}^{\prime}\)-dinindolylmethane and indole-3-carbazole, which bind to the aryl hydrocarbon receptor [186]. I3C is both an inhibitor and an enhancer of tumor formation in animals, depending upon the experimental system and the timing of administration in relation to exposure to carcinogen (see references within [187]). Consequently, there are potential limitations to the use of indole glucosinolates as chemoprotectors in humans because they (i) are weak inducers of phase 2 enzymes, (ii) are bifunctional inducers that activate phase 1 enzymes, (iii) may have estrogen receptor binding activity [188], and (iv) are potential tumor promoters\". Much of this early work on these indole GS metabolites focused on the fact that they can form tetrameric polymerization products that extremely closely resemble dioxin (2,3,7,8-tetrachlorophenoxyzo-\(p\)-dioxin (TCDD)) and have both estrogenic and anti-estrogenic activity. A significant part of our discovery of the cancer preventive effects of broccoli sprouts was that, in addition to being a source of high levels of glucoraphanin, broccoli sprouts had next to no indole glucosinolates, and were therefore not a significant potential source of I3C or DIM [5]. This is in direct contrast to market stage broccoli florets, which are relatively rich in indole glucosinolates. Much work has been conducted with I3C and DIM in subsequent years. Of particular relevance to this review, both additive effects and true synergies in the induction of Nrf2-regulated detoxication enzymes with reduced cytotoxicity have been reported between the SF and these two compounds [189]. Presently, there are 149 clinical studies on DIM and 11 on I3C listed on clinicaltrials.gov, suggesting a good safety profile--potential efficacy and mode of action in humans are a subject of intense current investigation, though definitive answers will not come for some time. Recently published human clinical work is suggestive of a protective effect, since one year of supplementation with DIM led to reduced breast density in BRCA positive women [190]. This is consistent with the many reports of DIM altering estrogen metabolism in healthy post-menopausal women and preventing cancer initiation and tumor development. Other roles of I3C/DIM include, most notably, their effects as negative regulators of estrogen metabolism, favoring a shift from the 16-hydroxy to the 2-hydroxy form of estrone (estrone 2-hydroxylation) [191]. This reduction in estrogen metabolites is known to activate the estrogen receptor, thus changing from a tumor-promoting to a non-tumor-promoting form, and has been long known [192].