Have you heard that some herbs and foods contain chemicals called “phytoestrogens” that work like estrogen in the body? Ever seen products being sold over the counter advertised to “feminize naturally” or “prevent hot flashes during menopause”? Or read conversations online about using over the counter products to feminize instead of prescribed hormones? Did you stop and wonder if there was truth to the claims? Let’s do a quick overview and do some debunking!
What are phytoestrogens?
Phytoestrogens are estrogen-like chemicals made by plants. Just like how the tobacco plant makes nicotine to defend itself against insects, phytoestrogens are thought to have a protective effect for the plant. One of the most commonly known phytoestrogen is soy isoflavone, which is found in soy beans and soy products. However other plants produce this compounds too. Red clover is another commonly found herb in herbal products.
As a side note: There are three forms of estrogen in the human body that are commonly talked about. Estradiol is the strongest. The type of estrogen used in modern-day hormone therapy is estradiol. So when you see estradiol in the rest of the article, feel free to mentally substitute “estrogen”.
Is it possible that phytoestrogens can feminize?
All things are possible.
First, let’s talk about dose. Phytoestrogens are found in very small doses in foods, or in slightly higher doses in supplements.
Medical transition requires high doses of hormones. A typical dose of estrogen today, when combined with an anti-androgen is around 4mg a day. Before antiandrogens were introduced, doses equivalent to 12mg of estradiol a day were used*. That’s a lot of hormone.
Phytoestrogen products do not come with an anti-androgen. Is it possible that they’re reaching the equivalent dose of 12mg of estradiol a day? Doses found in Canadian products ranged from 1mg to 35mg of phytoestrogens. So if phytoestrogens are equal in strength to estradiol, perhaps.
But that’s a big assumption. The body absorbs different drugs from the digestive tract in different amounts. Then that drug goes through the liver, where some portion may be activated or deactivated. And then it has to circulate around in the blood stream, find its way into the tissues of the body, and find its target. Pharmaceutical drugs have all these factors measured and calculated, so that the dose you’re given should ensure a certain dose is delivered into your tissues in the end. These herbs have not been studied in that way — so until more research is done, it’s difficult to know how much actually gets to the tissues. And it’s known that phytoestrogens bind to estrogen receptors only weakly, so they’re likely to have a weaker effect than estradiol.
In the doses that are being taken, do they have any effect?
As far as I can tell from the evidence, no. Phytoestrogens are marketed to cis women for relief from hot flashes. A study from 2003 published in JAMA found that they do not provide significant relief from hot flashes. Most of the clinical evidence that I’ve seen agrees with that study.
Worse, one study found that among cis women, those who were taking phytoestrogens had lower levels of estrogen in their blood than women who were not taking phytoestrogens.
While in theory phytoestrogens may possibly help with feminization, I see no medical evidence to suggest that they actually do.
Do phytoestrogens provide a consistent dose? Do the pills contain what they say they contain? Is there any regulation?
No. The dose ranges from company to company, pill to pill, season to season. Companies all have their own special formulations with different sources and types of phytoestrogens.
In the United States, supplements are not regulated by the FDA like drugs are. They’re in a special category. There are no independent checks to make sure the supplement is safe before it goes to market. There are no guarantees that the bottle actually has what it says it has. A Canadian study found wide variation in the amounts of phytoestrogens in various products.
Phytoestrogen supplements may seem to offer an accessible, easy way to feminize. However, there’s little to no evidence behind their use. And since they’re supplements, you’re never sure of what you’ll be getting. If you want to eat foods that are high in phytoestrogen, they’re not likely to do you harm. But from what I can tell of the literature, you’re better off saving that $20 to pay for an estrogen prescription.
If you’re having difficulty finding a physician who’s will prescribe hormone therapy, I urge you to call your local transgender or LGBT center, or visit the WPATH or GLMA website for provider listings.
*: These formulations were often from conjugated estrogens, which use a slightly different dosing. Doses of conjugated estrogens ranged from 7.5 to 10mg/day, and .625mg of conjugated estrogens is roughly equivalent to 1mg of oral estradiol. My figure of 12 mg of estrogen was using the “low” dosage of 7.5mg.