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What is the Truth About Anastrozole (Estrogen Blockers)?

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Many physicians and their patients know very little about the effect of estrogen blockers such as anastrozole. It's all too common for doctors to give these drugs to guys undertaking testosterone replacement therapy. Anastrozole (Arimidex ®), exemestane (Aromasin ®), and letrozole (Femara ®) are popular drugs that men take to stop the production of estrogen with a misguided belief that it's beneficial to their health. 

When our hormone experts talk to our patients for the first time, many ask if we prescribe estrogen blockers. The simple answer is no. Most guys find this unusual and expect us to throw a box of anastrozole in with their prescription. When we explain the reality of what estrogen does, the benefits it has, and how dangerous it is to block, they never look back.

Why Don't We Prescribe Anastrozole?

Estrogen is a byproduct of testosterone via an enzyme called aromatase. It, therefore, makes sense that administering testosterone will also increase estrogen levels. Testosterone has many benefits that are the result of its conversion to estrogen. However, most people are unaware of this fact.

If estrogen was so bad, why are no studies in the past 40 years exhibiting the adverse effects it supposedly has on the body? Compare that to the numerous studies showing the harm caused to the body when estrogen is blocked. 

When you give estrogen, you see an increase in bone density, a reduction in cholesterol, and reduced cardiovascular disease. Men treated with blockers like Anastrozole experience bone density loss (fractures), elevated cholesterol, and an increased risk of heart disease. 

In one report (1) it states:

"Osteoporosis and low bone mass are currently estimated to be a major public health threat for almost 54 million U.S. women and men aged 50 and older (2010 data). Among the 54 million, 10.2 million adults are estimated to have osteoporosis."

As men age, testosterone production slows, as does estrogen production. Along with that, the protection it offers the body reduces as well. By blocking estrogen with medication, you risk losing those benefits.

  • Erectile function and libido
  • Increased bone density
  • Regulation of fat mass vs. lean mass
  • Brain function
  • Lipid metabolism 
  • Skin health

We now know that testosterone's health benefits come from estrogen. That's why we don't prescribe anastrozole or other blockers. Estrogen is prescribed to women to help them maintain bone density and support brain function, heart health, immune system, sexual function, and libido. These benefits are the same for men, so why on earth would you take drugs to block them?

There are a few cases when estrogen blockers such as anastrozole are justified in small doses, such as increased estrogen sensitivity, which causes sore nipples and breast swelling. But, for the most part, you should never prescribe anastrozole with testosterone.

We often see patients who have been given estrogen blockers from traditional TRT clinics. These patients often have dangerously low estrogen levels. These guys are completely unaware that they run a higher risk of heart disease, bone density loss, Alzheimer's disease, high cholesterol, and memory loss.

A few clinicians also claim that raised estrogen in men causes an increased risk of prostate cancer. Again there is no medical literature to back this up, and this is purely speculation. One of Male Excel's lead doctors, Dr. Rouzier, states

''I am not aware of any studies in the last 50 years that have demonstrated an increased risk of prostate cancer is due to elevated estrogen levels.' If estrogen does indeed cause cancer, then the standard practice would be to block it in women too, which of course isn't the case."

Why Do Guys Take Anastrozole?

Testosterone therapy increases estrogen; there is no hiding this, but think about this fact. Why didn't doctors block estrogen when you were younger, when your testosterone levels were at their peak? Because it is good for you!

Estrogen is well known as a female hormone, which they produce in far more significant amounts than men. Contrary to popular opinion, as a man, estrogen will not make you 'womanly' or grow moobs (gynecomastia). It certainly won't make you more manly if you medically stop estrogen production!

Estrogen is Not the Enemy!

Many people who take testosterone to lose weight or build muscle see estrogen as an enemy. They believe that the more testosterone they take, the more is converted to estrogen and therefore wasted. So they assume taking anastrozole is their answer, thereby increasing testosterone. This approach is wrong for numerous reasons. 

Many fail to understand that fat is the issue, not estradiol (a form of estrogen). Excess fat, especially visceral fat around your belly and internal organs produce an enzyme that converts testosterone from fat into estradiol. The increased level of estradiol sends a signal to the brain to reduce testosterone production. The brain interprets this as there being too much testosterone in the body.

So, fat cells increase aromatase activity, creating more estradiol. Generally, men with excess fat have low testosterone. Through this aromatase cycle, you can conclude that estradiol is made from fat, not testosterone. It is not estradiol that is an issue; it is the fat.

So one would then assume that the next logical step is to block the estradiol with aromatase inhibitors – this is the wrong approach.

Studies show that if you do, you increase the chance of a heart attack. Yes, blocking estrogen can increase testosterone. However, your body needs estrogen, and blocking it can cause a variety of health problems such as:

  • Sexual dysfunction (ED, low desire, low libido, and reduced satisfaction).   
  • Poor cardiovascular health.  
  • Altered cholesterol levels (good and bad). 
  • Prostate issues
  • Decreased bone mineral density (osteoporosis)  
  • Poor insulin resistance (decreased lean muscle mass, increased belly fat, and diabetes risk).  
  • Compromised brain health and cognition issues. 

Being overweight is dangerous. Fat kills; it causes heart disease, diabetes, and often an early exit from this world. Many believe you can increase testosterone by blocking estradiol and use that to help burn fat and increase muscle. This concept sounds great, but unfortunately, testosterone relies on estradiol to sensitize your muscles to testosterone.

The answer is not to stop the estrogen. The answer is to give testosterone. Testosterone helps your body combat all the negatives that lead to visceral fat and help you lose this fat. We should be screaming the long-term health benefits of optimizing testosterone from the rooftops along with its close relationship with estrogen.

To sum up, blocking estrogen (estradiol) is 100% wrong, especially when undertaking testosterone replacement therapy. In particular, for overweight people, the answer is funnily enough to give estradiol in the form of testosterone.

Testosterone replacement therapy increases muscle and reduces fat. Testosterone, DHT, and estradiol all work together to protect you against all manner of age-related diseases. Next time someone tells you you should be on anastrozole, you can now correct them with confidence!

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Disclaimer: The information provided on this page is not a substitute for professional medical advice, diagnosis, or treatment. If you have any questions or concerns about your health, don't hesitate to contact us or consult your doctor.