What Are Phytoestrogens?

Whenever you take a bite of an apple or grab a salad for lunch, you’re getting more than just fiber and nutrients. You’re getting phytoestrogens. This type of plant-based estrogen is a naturally occurring compound that’s needed for our health.

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

Still, the role of phytoestrogens is often misunderstood.

What are phytoestrogens?

“Phyto-” is a Greek word meaning “plant.” Estrogen is a sex hormone that your body makes. It plays a key role in sexual and reproductive health.

“Phytoestrogen from foods have the same role as estrogen in your body,” says registered dietitian Michelle Dodd, RD, LD. “They’re a type of polyphenol or phytonutrient found in plants.”

Foods that have phytoestrogens

These foods have phytoestrogens:

Dairy milk and dairy products
Fruits, including apples, grapes and pomegranates
Herbs such as chasteberry
Legumes, including beans and lentils
Nuts and seeds, including flaxseeds
Soy and soy-based products, including soy milk, tofu and tempeh
Vegetables, like broccoli, carrots and potatoes
Whole grains

Potential phytoestrogen benefits

Scientists are still learning how phytoestrogens work in the body. Here’s a look at how phytoestrogens in foods may support your health and what the research shows.

1. May boost brain health

When it comes to phytoestrogens and your brain health, researchers are looking at the role they may play in protecting against cognitive decline and Alzheimer’s disease.

For example, one meta-analysis looked at 10 studies on menopausal women. It found that phytoestrogens in soy isoflavone supplements may improve thinking skills. The women also had slight improvements in visual memory. They took 60 to 120 milligrams of soy isoflavones every day for six weeks to 30 months.

And while these findings show some promise, more research is needed in a variety of other populations and age groups to understand how phytoestrogens affect brain health overall.

2. May ease hot flashes and menopause symptoms

Foods high in phytoestrogens, like soy, may help reduce menopausal symptoms. In fact, soy is among the many foods you should eat to reduce hot flashes. That’s because phytoestrogens act like natural estrogen in your body.

In one study, perimenopausal and postmenopausal women took 40 milligrams of soy isoflavone supplements twice a day for 12 weeks. They reported less:

Still, Dodd says more research is needed to fully understand how phytoestrogens affect menopause.

3. May strengthen bones

Low estrogen levels can weaken bones, especially after menopause.

In 2016, researchers reviewed 23 studies and found that phytoestrogen supplements may improve bone density in older women. But in a 2019 article, researchers reviewed 85 studies. They found that while phytoestrogens might be helpful, we need more investigation to understand how safe and effective they truly are.

4. May lower cancer risk

Experts are still trying to determine what role — if any — phytoestrogens play in lowering or increasing cancer risk. We know that high estrogen levels are a risk factor for breast cancer. In the past, researchers questioned whether soy could raise the risk of estrogen-dependent cancers. But more recent studies show that eating soy doesn’t cause breast cancer.

Some older research indicates that a phytoestrogen-rich diet, especially during childhood, may lower breast cancer risk. One study found that participants who got 10 milligrams of soy each day (approximately 1 to 1 1/2 cups of soy milk) had a 12% lower risk of breast cancer. Other research shows that women with breast cancer who eat soy are less likely to have cancer recurrence.

Still, the debate — and research — continue. “There’s much we don’t know,” reiterates Dodd. She recommends talking to your healthcare provider about phytoestrogens if you have or are at risk for estrogen-driven cancers such as:

Phytoestrogen risks

In most cases, phytoestrogens are good for you. But you can overdo a good thing.

“If you eat soy at every meal — tofu for breakfast, edamame for lunch, a soy-based meat substitute for dinner — phytoestrogens may build up in your body over time,” shares Dodd. “That could cause gastrointestinal issues.”

If you have (or are at risk for) estrogen-dependent cancer, talk to your healthcare provider before loading up on phytoestrogen-rich foods or supplements. In addition, people with thyroid issues, like an underactive thyroid (hypothyroidism), may also need to limit soy and other phytoestrogen-rich foods.

“Soy, in particular, can affect your body’s ability to absorb and use thyroid hormone medications,” she continues. “You may develop an iodine deficiency.”

Your healthcare provider may recommend avoiding soy and soy-based foods for a few hours before and after you take the medication.

Bottom line? It’s OK to eat phytoestrogen-rich foods

The small amounts of phytoestrogens in plant-based foods are unlikely to cause health problems, and the benefits of eating fruits and vegetables are far more important for your overall health. “Your body needs fruits, vegetables and whole grains that have phytoestrogens,” reinforces Dodd.

But you should always talk to a provider before taking phytoestrogen supplements. “As long as you eat a healthy variety of foods,” says Dodd, “you’re unlikely to be low in phytoestrogen or need supplements.”