To understand why you might need an anti-estrogen supplement, it is crucial to understand aromatization. This is the natural bodily process by which the enzyme aromatase converts testosterones to estrogens. Since the human body always wants to maintain homeostasis, an influx of testosterone from performance enhancers triggers aromatization. This causes more estrogen to be produced, resulting in those estrogenic side effects that no bodybuilder wants to experience. (Gynecomastia, anyone?)
Estrogen does plenty of good things in the body, like increasing bone mass and even muscle mass when combined with testosterone. But hormones are tricky things, especially when they are out of balance. Excess estrogen poses more risks than giving male athletes “man boobs.” High levels can cause water retention, elevated blood pressure, reduced immunity, and high cholesterol.
Both AIs and SERMs are used to control a new, high volume of estrogen in response to steroids or testosterone supplements.
Aromatase Inhibitors (AIs)
AIs inhibit aromatase, the conversion enzyme. They lower serum estrogen, but they only affect conversion; they do not stop the ovaries from producing estrogen.
This can be a good thing for women because estrogen is essential for both sexes; the only problematic estrogen in this case is the excess converted from the supplement-elevated testosterone.
Pros: Because AIs have a direct effect on aromatization, they are highly effective.
Cons: They can negatively impact cholesterol. This is exacerbated when AIs are taken with exogenous testosterone.
Selective Estrogen Receptor Modulators (SERMs)
SERMs do not directly affect serum estrogen levels. Instead, they fill the estrogen receptors of cells and keep estrogen from attaching. When estrogen does not attach, it cannot affect the cell.
There are estrogen receptors in other cells in the body, but they do not all have the same structure. This is why SERMs are called “selective.” Additionally, if a SERM blocks estrogenic activity in one tissue, it may exacerbate it in another.
That is not necessarily a bad thing; in the liver, estrogen-like activity can promote good cholesterol. This may be why the main benefit of SERMs over AIs is the lack of damage to lipid profiles.
Pros: SERMs have no negative impact on cholesterol. They often combat gynecomastia successfully.
Cons: They may not prevent water retention for men.
Both aromatase inhibitors ais vs selective estrogen receptor modulators serms have a place in estrogen control. Despite the cholesterol concern of AIs, they are very effective at lowering excess estrogen, which has health risks of its own. SERMs might not be as effective as AIs, but they present lower health risks.