Isn't an AI expected to lower SHBG because of the increase in testosterone and decrease in estradiol? Perhaps DIM's estrogenic effects are responsible for the rise in SHBG.
A separate study shows that DIM's estrogenic effects can be mediated through ERβ but not ERα activation of estrogen response element and DIM selectively activated multiple endogenous genes through ERβ[40]. The possible mechanisms by which DIM induces these effects do not involve binding to ERβ but may involve a ligand-independent mechanism by recruiting coactivators to target genes[40]. It was reported that induction of p21 expression by DIM was independent of estrogen-receptor signaling[21].
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To be clear I have no science behind DIM acting as an AI lol - just a general trend from my (n=1) labs that DIM significantly raises my SHBG while seeming to not effect total E2. I used to have a bunch of bookmarks on SHBG metabolism and was going to make a post here about 6 months ago for the low SHBG guys, but I've had some other health issues, stopped taking DIM, and got a new computer and lost most of those bookmarks. Oops
As far as SHBG - my question boils down to how exactly is DIM raising SHBG? Like as in your link we know DIM can have estrogenic effects - but if DIM was so powerfully acting as an estrogen, enough to significantly increase SHBG, wouldn't people notice those effects while taking it? I mean, how much would you have to increase your E2 levels to increase SHBG by 10 units? I'm guessing enough that you'd notice some negative effects.
Low SHBG is negatively associated with a lot of health issues - for instance, insulin resistance and obesity can lower SHBG, but it appears to be a positive feedback loop - insulin sensitivity lowers SHBG, which lowers insulin sensitivity, etc. etc.
Your link shows DIM activating ERβ, but not ERα. My original thought was that perhaps the liver, where SHBG is mainly produced, has an extremely high density of ERβ, and very little ERα. Now read this link:
Estrogen Receptor beta (ERβ) Regulation of Lipid Homeostasis—Does Sex Matter
Some outtakes:
E2 treatment reduces adiposity in both sexes and improves metabolic adaptation to obesity through the activation of both ERs [3,4]. However, it also mediates cell proliferation through activation of ERα present in target tissues and can thus contribute to malignant growth in these tissues. These detrimental effects render the use of E2- and/or ERα-selective agonists as a treatment for obesity difficult, whereas ERβ is thought to counteract these activities [5]. Recently, selective activation of ERβ has demonstrated beneficial outcomes on metabolic control in obesity [6,7,8,9], probably through feedback mechanisms, since ERβ is expressed at very low levels in metabolic tissues including the liver.
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Indeed, liver cells express very little the ERβ subtype compared to ERα; therefore, the effects observed by the activation of ERβ by a ligand might result from a feedback loop or crosstalk from other tissues.
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More recently, extensive research has demonstrated beneficial metabolic outcomes of ERβ activation and has defined a central role for ERβ in metabolic control. However, further research is needed to elucidate the role of ERβ in lipid homeostasis. Targeting ERβ in order to tackle metabolic disorders associated with obesity without inducing the side effects of ERα activation could be a potential solution
It appears to be the opposite of my original theory - the liver has relatively little ERb compared to ERa. However, "Targeting ERβ in order to tackle metabolic disorders associated with obesity without inducing the side effects of ERα activation" isn't this exactly what DIM does? And is it possible that some of these benefits are due to an increase in SHBG?
As far as DIM acting as an AI - I really wish we had a relatively accurate "Free E2" calculator, like we do with Free Testosterone. That way we could see how much you would expect Total E2 to raise, given an increase in SHBG.