Estrogen blockers are supplements that counter the action of estrogen, the primary female sex hormone.
They're similar to testosterone boosters except they specifically address the blocking of estrogen.
It generally works in opposition to testosterone, meaning high levels of estrogen will cause you to gain fat, lose muscle mass, and, for men, lose their libido and sexual potency.
None of these are good things, especially if you are looking to get stronger and perform better as an athlete. We’ve combed through a huge number of supplements to come up with the best estrogen blockers on the market.
PrimeMale attacks the causes of low androgen levels and high estrogen levels on all fronts. First, it takes care of anything that could impair your testosterone levels with a strong dose of vitamin D, magnesium, and zinc.
Next, it’s got Asian ginseng, a powerful androgen booster, as well as aspartic acid, nettle root, and boron. The bioavailability of all of these ingredients is augmented by BioPerine, a proprietary black pepper extract.
This broad-based strategy to suppress estrogen and boost androgens makes PrimeMale our top pick.
2. MAN Sports Nolvadren XT
MAN Sports Nolvadren XT provides an unusual take on estrogen blocking. It uses diindolylmethane to block estrogen, which is standard practice, but it uses some unconventional compounds to boost testosterone and to control cortisol levels as well.
This is great to see, because as important as testosterone and estrogen are, cortisol is an underappreciated factor when it comes to muscle gains and energy levels.
The testosterone booster and the cortisol blockers are advanced metabolites, and you won’t find them anywhere else. If standard estrogen blockers aren’t cutting it, give Nolvadren XT a try.
3. Genius Estrogen Balance
If you want straight, simple, anti-estrogen power, Genius has got you covered.
Typically known for their cutting-edge supplements that use the latest extracts and compounds, their Estrogen Balance formula goes with just two active ingredients: diindolylmethane and grape seed extract. These come alongside BioPerine for better absorption and bioavailability.
As you’d expect from a company like Genius, there are no artificial ingredients or fillers to worry about.
AndroSurge provides potent anti-estrogen effects thanks to its use of rhodiola root extract, diindolylmethane (DIM), grape seed extract, and eurycoma longifolia extract.
These, along with the traditional testosterone-boosting ingredients zinc and vitamin D, should be enough to give you substantial gains in your strength, power, virility, and energy levels. The fact that it has no extra fillers or artificial ingredients is an added bonus.
5. Muscle Force Estrotase
Estrotase uses a solid blend of estrogen-blocking and androgen-producing ingredients such as zinc, maca root, grape seed extract, diindolylmethane, boron, and kudzu root.
It’s sourced from natural materials and has no extraneous ingredients, making it a solid call for anyone looking for an all-around anti-estrogen supplement.
EstroVoid has a high concentration of estrogen blockers such as diindolylmethane, panax ginseng, and ashwagandha.
The only downside is that it uses a proprietary formulation, so you can’t precisely compare this supplement to others with similar ingredients.
Still, most of the ingredients are solid, and the overall dosage of estrogen blockers is high, making it a pretty solid choice.
7. Reborn Labs Anablox Xtreme
Anablox Xtreme uses a mixture of estrogen blockers and androgen boosters to achieve its desired effect, alongside a selection of supplements to boost liver function.
The consequence of a supplement design strategy like this means that the ingredients are spread fairly thin.
While this supplement has some of the same ingredients as the top-ranked estrogen blockers, the amounts included are much lower.
EstreduxHP is based around a proprietary blend of several ingredients with known anti-estrogen or pro-androgen effects.
These include Panax ginseng, ashwagandha, diindolylmethane, and eurycoma longifolia. However, the fact that the blend is proprietary means that you can’t find out how much of each ingredient is actually in the supplement.
If you trust the nutritionists, this is not such a big deal, but it makes it hard to compare and contrast between other estrogen blockers, which knocks it down somewhat in the rankings.
9. Pride Nutrition E-Block
E-Block from Pride Nutrition is a pretty straightforward formulation, relying on diindolylmethane and chrysin (a compound found in honeycomb) for its anti-estrogen effects.
With chrysin being a little-researched compound, this supplement effectively relies on DIM for all of its anti-estrogen effects. With a design this simple, it’s just straight-up outcompeted by other estrogen blockers on the market.
Estroblock sells well, but it doesn’t quite cut it compared to the top estrogen blocking supplements. It too uses a proprietary blend, making it difficult to identify how much of each active ingredient is used in the formulation.
The overall content of active ingredient is quite low, however, and aside from diindolylmethane, it doesn’t have any of the most effective estrogen blockers. Most people will find better options elsewhere.
Estrogen blocker benefits and side effects
Estrogen blockers are supplements that reduce the production or biological activity of estrogen, the female sex hormone.
Estrogen works more or less in direct opposition to testosterone, so all the benefits of high testosterone (strong sex drive, easy lean muscle gains, high energy levels, and little trouble losing body fat) can be counteracted by high levels of estrogen in your body. Hence the need for an estrogen blocker.
Men who are already pushing the limits of their natural testosterone levels (for example, by using a testosterone booster as part of their regular supplementation routine) might benefit more from trying to reduce estrogen versus trying to increase their testosterone levels even more.
There’s just more headroom to improve in that direction for many men. But what’s it take to decrease your estrogen levels?
One supplement that’s on the cutting edge of estrogen blocking research is diindolylmethane, also known as DIM. The utility of DIM in reducing estrogen levels was discovered initially by cancer researchers.
Some cancers, such as thyroid cancer, are many times more common in women than men. Given that one of the most significant metabolic differences between men and women is estrogen levels, estrogen and cancer is an area of active research.
DIM can block estrogen. One scientific paper published in 2011 flagged DIM as a potent anti-estrogen compound while researching it as a treatment for thyroid cancer (1).
The researchers discovered that DIM resulted in a strong anti-estrogen effect. Later research published in 2016 in the journal Anti-inflammatory Nutraceuticals and Chronic Diseases showed that DIM has strong anti-estrogen and anti-inflammatory effects.
While this paper focused specifically on using DIM to treat or prevent cancer and heart disease, this is good news for people who want to reap the benefits of higher androgen levels too (2).
Grape seed extract works well too. A similar mechanism is at play in other anti-estrogen compounds, such as grape seed extract. Research (again focused on cancer cell metabolism) published in 2003 found that grape seed extract contains biologically active compounds that inhibit estrogen production (3).
This indicates that, in addition to DIM, you should be on the lookout for estrogen blocking supplements that contain grape seed extract.
What are the consequences of high estrogen levels? Observational studies give some indication of the negative consequences.
Estrogen is linked to obesity. One natural experiment that demonstrates what happens when testosterone levels drop and estrogen levels increase is the metabolic changes that take place in obesity. According to research published in 1999 by P.G. Cohen, people with morbid obesity experience a progressive shut-down in testosterone production and an increase in estrogen production (4).
Since one of the primary consequences of low testosterone and high estrogen is gaining fat mass and losing muscle mass, this sets off a positive feedback loop, making it very difficult to stop gaining fat.
The same double-whammy of low testosterone and high estrogen is observed in elderly men. A large cohort study of elderly men published in the Journal of Clinical Endocrinology & Metabolism found marked health risks associated with low testosterone and high estrogen levels (5).
Men with both low testosterone and high estrogen were more likely to be overweight, have diabetes, frailty, and cardiovascular disease. All of these outcomes appear to be connected with low muscle mass and high body fat content.
The effects of estrogen and testosterone appear to be substantially worse in men above age 60. Men over this threshold have a 20% chance of having testosterone levels that are below the healthy range for young men, according to a 2005 study in the journal Endocrine Reviews (6).
This means that estrogen blockers aren’t just for young guys looking for muscle gains—older men should consider an estrogen blocker too, if they feel they are suffering from the negative effects of low testosterone and high estrogen, namely, decreasing muscle mass, increasing fat mass, low energy levels, and a low libido.
The benefits of higher testosterone and low estrogen seem to extend beyond the physical, too. One study suggests that cognitive abilities could be enhanced in older men who keep their testosterone levels high and their estrogen levels low.
The study, published in 1999 by researchers at the University of California San Diego, looked at testosterone and estrogen levels among a group of over 500 men age 59 and up (7).
The men had standard blood tests done to check their hormone levels, then underwent a series of tests of cognitive ability, including tests for memory, visual reasoning, and overall mental state.
Low estrogen means better cognitive performance. Even after adjusting for potentially confounding factors like age, smoking status, and body weight, the men with high testosterone and low estrogen performed better on the cognitive tests compared to the men with low testosterone and high estrogen.
This indicates that older men who are feeling “foggy” or a little less mentally sharp than they used to be might not be just getting old—they might have low testosterone and high estrogen levels.
Fortunately, the most effective estrogen blocking supplements appear quite safe.
Even after six years of a commercial DIM supplement being used in clinical research, no serious adverse effects have been reported (8).
In the case of grape seed extract, it’s been used in clinical research with no major adverse effects in studies up to 14 weeks in duration, but you shouldn’t use it if you are on blood thinners like warfarin, or if you have an allergy to grapes (9).
The safety profile of other estrogen blockers is less clear, as they have ingredients that haven’t been tested in rigorous clinical trials.
Since many of the most effective estrogen blockers, such as diindolylmethane and grape seed extract, are fairly new, details on optimal doses are still a little sketchy.
As for grape seed extract, recommendations vary as well, from 100 to 400 mg per day. Beyond this, the top-ranked estrogen blockers all do a great job balancing out active ingredients, so it’s hard to go wrong following the dosage recommendations of a quality estrogen blocker.
Estrogen blockers aren’t just for super-athletes. Men looking to get out of the destructive positive-feedback loop of weight gain, increased estrogen, and decreased testosterone can benefit greatly from an estrogen blocker, as can men who are getting older and are feeling the effects of decreasing testosterone with age.
High estrogen and low testosterone isn’t just for physical benefits, either; older men can gain cognitive benefits from increasing their testosterone levels and decreasing their estrogen levels.
When you’re looking for an estrogen blocking supplement, look for one that includes diindolylmethane, and preferably grape seed extract too.
These are two of the best-researched estrogen blocking compounds, and they have a strong track record of inhibiting the activity of estrogen in your body. Other compounds that boost androgen production, such as zinc and magnesium, can be helpful too.