833. From broccoli to red wine, certain foods are promoted as natural estrogen blockers. Is there any science to support the claims?
833. From broccoli to red wine, certain foods are promoted as natural estrogen blockers. Is there any science to support the claims?
References
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The internet is pitching aromatase-blocking diets and supplements as a way to fight estrogen dominance in men. So, do they work? And is this even a real problem? Today, we’re separating the fact from the fiction
Hello, I’m Monica Reinagel and you are listening to the Nutrition Diva podcast, a show where we take a closer look at nutrition news, research, and trends and answer your food and nutrition questions.
Today’s episode was inspired by an email from a listener who stumbled across some online advice warning about an enzyme called aromatase. This enzyme, the source claimed, turns testosterone into estrogen and might be to blame for all sorts of problems which they, of course, had a plan to fix with diet and supplements.
The listener dismissed it as hokum at first, but then saw some more reputable sources suggesting that foods like cruciferous vegetables, mushrooms, and red grapes might help keep aromatase in check. And now he’s wondering: is there anything to this? And, as is so often the case, there is actually a kernel of truth here. However, it’s been wrapped in several layers of misinterpretation or distortion. So, let’s get in there and sort fact from fiction.
Aromatase is an enzyme that converts testosterone into estrogen. It’s produced by both men and women by a variety of organs and tissues—including the ovaries (in women), the testes (in men), as well as the brain and fat tissue. In fact, after menopause, fat tissue becomes the primary site of aromatase activity (and estrogen production) in women. (Tuck that fact away for now; it’ll be important later.)
The ability to aromatize testosterone into estrogen is important for both men and women. Estrogen is central to women’s reproductive health, of course. But estrogen also supports healthy bones, brain function, and even libido–in both men and women.
Although some aromatase activity is generally desirable, there are a few medical situations where aromatase-blocking drugs are used. The most common of these is hormone-sensitive breast cancer. They may also be prescribed in very specific cases of male infertility or estrogen excess. But very high aromatase activity in men is quite rare.
It is true, however, that testosterone levels can dip as men get older, which can contribute to issues like low libido, reduced energy, or declining muscle mass. And I think it’s that very common concern that online “estrogen-lowering” protocols are tapping into.
Taking an aromatase inhibiting drug because your testosterone level isn’t quite what it was when you were 25 would be like bringing brass knuckles to a game of patty-cake—total overkill. And the side effects are no joke: these drugs can cause bone loss, joint pain, even hot flashes. But what about these foods that are said to reduce aromatase activity? Might they be useful in this situation?
Some foods do contain natural compounds that can, at least in a test tube, reduce aromatase activity. These include parsley, celery, red grapes, green tea, cocoa, cruciferous vegetables and mushrooms. And then there’s soy, which deserves a special mention.
Soy contains phytoestrogens—plant compounds that can bind to estrogen receptors. For a long time, soy was described simply as an “estrogen mimic,” which fueled concerns about feminizing effects in men. But research has shown the story is much more complicated. Although soy may have a modest impact on aromatase activity, eating soy foods does not appear to meaningfully affect hormone levels or activity in men or women.
So, there is a scientific basis for saying that certain foods may influence aromatase activity. But before we all start loading up on broccoli and mushrooms in a bid to boost testosterone levels, let’s look at what the human studies show.
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So far, most of what we know about foods and aromatase comes from laboratory studies or animal experiments. In humans, the picture is much less clear.
Observational studies have found that people who follow a more Mediterranean-style diet—lots of fruits and vegetables, fish, whole grains, olive oil, small amounts of dairy, meat, and alcohol, and not so much sugar or fried food—tend to have lower estrogen levels. This has been especially noted in postmenopausal women. But these studies can’t tell us exactly which foods or nutrients are responsible, or even whether the effect has anything to do with aromatase activity. It may just be that a high-fiber, nutrient-rich diet supports healthier hormone metabolism in general.
Intervention studies, where people are assigned to a specific diet or supplement, are rarer. In women with breast cancer, some small trials suggest that soy isoflavones or omega-3 fatty acids might modestly influence estrogen pathways. But direct effects on aromatase activity in humans are hard to document, and results are inconsistent.
All in all, any direct effect of foods or diet on aromatase activity (and estrogen levels) appears to be very minimal. That said, even if cruciferous vegetables, mushrooms, or red grapes aren’t dramatically blocking aromatase in your body, that doesn’t mean they’re useless. Most of the foods promoted as aromatase-inhibitors are super-nutritious foods with well-established health benefits. And when people adopt these protocols, they’re usually also doing other things that improve the nutritional quality of their diet—like cutting out fried foods, reducing added sugars, limiting empty calories, and adding resistance training. These steps can reduce excess body fat, improve metabolic health, and build lean muscle, all of which can have a positive impact on hormone balance.
In terms of the supplements that are sometimes recommended, a lot of the products are plant compounds extracted from the foods I mentioned earlier. And while some do show anti-aromatase activity in lab models or animals, the leap is assuming that taking them as pills produces meaningful changes in humans. Unfortunately, the few human studies we have tend to be quite small and they are usually tracking surrogate markers (such as circulating hormones) rather than aromatase activity itself. The effects, when they are seen, tend to be quite modest. But that doesn’t mean that there’s nothing you can do to impact hormone health.
Remember earlier I mentioned that once women go through menopause, fat tissue is the primary source of aromatase activity and estrogen production. Well, fat tissue also contributes to aromatase activity in in men. Which is why excess body fat tends to increase estrogen production–in both men and women. In fact, if you’re concerned about high estrogen levels or low testosterone, losing excess body fat may be the most direct path to improved hormone balance. A study using pharmaceutical aromatase inhibitors provides a useful illustration of this reality.
A clinical trial involving men with obesity put all of the subjects on a structured weight-loss program. Half also received a prescription aromatase inhibitor, while the other half got a placebo. As expected, the group using the drug saw testosterone rise and estrogen fall more than the placebo group. But when it came to outcomes that really matter—muscle strength, sexual function, energy, quality of life—the drug added nothing beyond what weight loss alone delivered.
So, let’s sort fact from fiction:
The real benefits of these diets come not from tinkering with aromatase but from improving overall diet quality, reducing excess body fat, and supporting metabolic health. Those changes can, in turn, help maintain a healthier balance of testosterone and estrogen. So, if you enjoy mushrooms, cruciferous vegetables, or red grapes, go for it! They’re good for you in lots of ways. Just don’t expect them to be a magic fix for testosterone levels—or fall for expensive supplement regimens that play on fears about “estrogen dominance.”
If you’re worried that your hormone levels might truly be out of whack—whether that’s unusually low testosterone, or symptoms that don’t seem typical of normal aging—your best bet is to talk to your doctor and get properly evaluated. That way you’ll know whether there’s really an issue and, if so, what safe and effective treatments are available. And please, if you have a history of hormone-sensitive cancer, please check with your oncology team before using any supplement marketed for hormone effects. Even though the marketing claims are often exaggerated, better safe than sorry.
If you have a question you’d like me to answer, you can email me at nutrition@quickanddirtytips.com. If you’d like to find out about having me speak at your next live or virtual event, you can learn more at wellnessworkshere.com
Nutrition Diva is a Quick and Dirty Tips podcast. Holly Hutchings is our Director of Podcasts. Steve Riekeberg is our audio engineer, Morgan Christianson heads up Podcast Operations & Advertising. Rebekah Sebastian is our new Manager of Marketing and Publicity Thanks also to Nat Hoopes for his support and most of all thanks to you for listening!