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How Do Anti-Estrogens Work?

The average male has a testosterone level that is between 300 and 700 nano-grams per deca-liter of blood (ng/dl).  This broad range is affected by a variety of factors and aromatase is one of them.  Most AI’s have shown the ability to raise testosterone to levels approaching 1200ng/dl but this has never translated into muscle growth.  You may have heard the term PCT on many of the steroid forums. After a cycle of pro-hormones and steroids, the male testes tend to shrink and lower natural production and the use of anti-estrogens helps reverse this effect faster than natural recovery alone.  With anti-estrogens, there are two basic technologies that have similar effects.

The first are anti-aromatase agents, which limit the aromatase enzyme that converts testosterone to estrogen.  The body has a feedback mechanism for estrogen that senses when estrogen levels get too low (the male body DOES need estrogen to function).  If the estrogen levels get too low, then the body responds by making more testosterone which in theory converts to estrogen and corrects the problem.  Estrogen (or lack of) is sensed by the pituitary gland and the testes are instructed via Luteinizing hormone to make more or less testosterone. So, by lowering estrogen artificially, the body is told to make more via increasing testosterone.Anti-aromatase agents temporarily lower estrogen to trick the body into producing more testosterone.  This actually works really well, but there can be negative effects.  Prescription Anti-Aromatase products are Arimidex(R), Letrozol(R) and Exemestane(R).  These ingredients are illegal to sell to males except for special circumstances like breast cancer, but we have many natural agents that do the same thing which is great for the bodybuilder who is trying to increase natural testosterone levels or recover from a cycle of steroids.

Aromatase Inhibitors:
These limit the conversion of testosterone to estrogen by binding and inactivating the aromatase enzyme, which has the downstream effect of raising testosterone via a feedback loop that is dependent on estrogen (estrogen is reduced, so the body creates more testosterone as a raw material)  AI’s have two methods of reduction.  First, there is a suicide inhibitor, which locks up and deactivates the enzyme. The other method, competitive inhibition only temporarily blocks the enzyme from having activity.  The items on the bodybuilding market are suicide inhibitors, which still work well enough to cause a major increase in testosterone for most males however these will not really work in females unless via some other pathway such as DHEA. Sadly in the current studies, this reduction in estrogen and the boost in testosterone doesn’t translate into muscle gain, which is puzzling.  I think if properly stacked with other items this could be a very good way to increase testosterone, but it seems that the body has many ways of reducing excess testosterone or the lab is seeing cross reaction which is the AI itself “looks” like testosterone on the test.  The debate of whether to use AI’s as a valid means to boost testosterone is one that is heated.  Many experts and honestly most pharmaceutical steroid recovery agents are competitive ER inhibitors like Tamoxifen (NolvadexTM) which is interesting.  The problem with any of the competitive receptor blockers on the market is that they suffer from rapid metabolic clearing via sulfation and glucoronidation.

This process is how the body removes anything that isn’t food and there is a ton of it in the liver, making oral products very difficult design with any positive effect due to the rapid clearing of the ingredient.  Ways around these metabolism routes are sublingual delivery (under the tongue), transdermal delivery (on the skin) or by blocking them with additional items that compete for the enzyme.