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What is: Aromatase and Aromatase Inhibitors

Aromatase and Aromatase Inhibitors Aromatase is an enzyme found in the liver, responsible for the conversion of the androgens androstenedione and testosterone into the estrogens estrone and estradiol. Inhibiting aromatase can cause the body to produce less estrogen and maintain a higher testosterone state. The main side effect in men from too much estrogen is gynecomastia (bitch tits). In order to prevent gynecomastia, you hear bodybuilders talking about using anti-aromatase supplements to suppress aromatase and therefore prevent more estrogen from being produced.

Other factors known to increase aromatase activity include age, being overweight, insulin production and levels, gonadotropins, and alcohol consumption. Aromatase activity can be decreased by prolactin, anti-müllerian hormone, and smoking (but don't take that to mean you're supposed to start smoking!).

Clinically, aromatase inhibitors are in the management of patients with breast cancer whose cancer has been found to be estrogen receptor positive. In such a case, inhibiting aromatase and slow down or stop the growth of the cancer and enable more effective treatment. Aromatase inhibitors are also being prescribed to men on testosterone replacement therapy (TRT) as a way to keep estrogen levels from increasing when testosterone is introduced.

Letrozole is an aromatase inhibitor marketed originally as Femara. Extracts of certain (white button variety: Agaricus bisporus) mushrooms can inhibit aromatase. (Anti-aromatase activity of phytochemicals in white button mushrooms (Agaricus bisporus))

Increasing your testosterone results in aromatase working to convert some of that testosterone to estrogen, which in turn will shut off some of the testosterone effects. Aromatase is primarily concentrated in the skin, especially over adipose, in the scrotum, and around the nipples. Excess fat cells can contribute to an increased amount of aromatase, and nutrient deficiencies can also produce higher levels. Inhibiting the production and function of aromatase will preserve and stimulate more testosterone induced activity (which is what most lifters want).

Some common causes of increase aromatase activity:
  • Aging
  • Zinc deficiency
  • Obesity
  • Carbohydrate intolerance and insulin sensitivity
  • Overuse of alcohol
  • Liver function changes
  • Prescription drug side effects, especially diuretics and liver activity drugs
There's a recent opinion developing that prostate cancer has more to do with estrogen than with dihydrotestosterone, the theory being that many men, as they age, convert too much testosterone to estrogen and that this excessive estrogen is the cause of prostate enlargement or prostate cancer.

So, from reading all the above, it sounds as though inhibiting aromatase and/or blocking the production and effects of estrogen can be a good thing. That's where aromatase inhibitors come in.

Indole-3-Carbinols are found in cruciferous vegetables like cabbage, brussel sprouts, cauliflower, collards and broccoli can help transform estrogen. The activity of Indole-3-Carbinols is recognized by the National Cancer Institute and have also been shown to stop the growth of breast-cancer cells by inhibiting the action of a specific enzyme.

Chrysin is a flavone compound found in the herb Passiflora incarnata and is a potent natural aromatase inhibitor. In a 1993 study, chrysin and 10 other flavonoids were compared to an the aromatase-inhibiting drug aminoglutethimide. Chrysin probed to be the most potent aromatase-inhibitor, similar in potency and effectiveness to the aromatase-inhibiting drug. Chrysin is also a potent antioxidantthat can provide an anti-inflammatory effect.

Apigenin, a flavone found in most species of Chamomile, is another safe and effective aromatase inhibitor with an inhibitory effectiveness about equal to chrysin.

The isoflavones in soy, most notably genistein and diadzein, were shown in studies to be potent aromatase inhibitors.

So that begs the questions: Do you want to inhibit the production of estrogen? Or is the effects of excess estrogen that we want to inhibit?

Opinions online vary. Some advanced lifters don't recommend aromatase inhibitors, the reasoning being that the body is too smart for us. When we increase testosterone, the natural response of our body - on an attempt to maintain proper hormone balance - is to signal for the production of more estrogen.

The theory behind using an aromatase inhibitors in relation to prohormones or steroids is to keep the body from producing more estrogen while testosterone levels are increased. As part of post-cycle-therapy (recovery after a steroid cycle), an aromatase inhibitor is used until testosterone levels return to normal and the body is no longer signaling for more estrogen to be produced.

But by using an aromatase inhibitor, estrogen levels still remain low, as we are actively preventing the body from doing what it's trying to do. That means the body will keep signaling for more estrogen while waiting for the testosterone levels to reduce. There's some suspicion that aromatase inhibitors make the body want to produce MORE aromatase, since it's not seeing the estrogen production increase that it's looking for. There's also potential for ending up with too little estrogen. Both of these scenarios can result in a rebound type effect where once the aromatase inhibitor is stopped, the body stays in overdrive trying to make estrogen, cause levels to spike.

Many advanced bodybuilders are foregoing aromatase inhibitors and use a SERM (selective estrogen receptor modulators). Instead of blocking the production of estrogen, SERMs block the effects of estrogen by preventing it from binding to estrogen receptors. Now the body doesn't know the activity of the estrogen is being blocked, so it's happy, thinking the balance between testosterone and estrogen is a-OK. IN theory, this provide for a more rapid return to stasis between the two hormones, since the body will naturally lower aromatase as testosterone levels return to normal.

So should you or shouldn't you use an aromatase inhibitor? Personally, I say no. Use a SERM if you can get it. If you can't get a SERM, or are convinced an aromatase inhibitor is needed, I recommend you have your estrogen level tested an monitored by a physician while you're using. The effects of too little estrogen can be as bad as, or even worse, than too much.
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