The Facts on Phytoestrogens and Hot Flashes

“Phytoestrogen” has become a nutritional buzzword during perimenopause.

Researchers are interested in learning more about phytoestrogens and menopause because Asian women (who typically eat a diet rich in phytoestrogens) have far fewer hot flashes than American or European women.

These efforts have generated data to help better understand the role of these plant compounds in helping manage menopause symptoms. Read on to learn if phytoestrogens are right for you.

Phyto-what?

“Phyto-” means “from or related to plants.” Phytoestrogens are plant molecules that have a similar chemical structure to estrogen. They act similarly to estrogen in the bodies, so they bind to estrogen receptors on cells.

Estrogen is one of the two main hormones that significantly decline during the transition through menopause. This estrogen decrease is responsible for the uncomfortable symptoms that many women experience, like hot flashes, night sweats, insomnia, and vaginal dryness.

Foods vs. Supplements

Phytoestrogens can be divided into two major categories: isoflavones and lignans.

Isoflavones

• Soy is the most popularly studied and richest source of isoflavones. You can eat soy in the form of soybeans (edamame), miso, soy nuts, tempeh, tofu, soy flour, soymilk, and soy-based meat substitutes (like veggie burgers).
• Chickpeas and green peas contain isoflavones, but in far lesser amounts than soy.
• Red clover is a legume rich in isoflavones. It is typically taken in supplement form, like capsules, powder, or liquid.

Lignans

Lignans are found in berries, seeds (especially flaxseeds), grains, nuts, and fruits. They are not studied in connection to menopause nearly as frequently as isoflavones are.

Do Phytoestrogens Help with Symptoms?

Many studies have tried for decades to determine if phytoestrogens help with menopause symptoms, but the results are varied.

Hot flashes

A 2015 meta-analysis of 10 clinical studies found that postmenopausal women who took phytoestrogen supplements had significantly fewer hot flashes.

A systematic review found that phytoestrogens significantly reduced hot flashes and co-occurring symptoms like depression, anxiety, and insomnia. These authors said these results look promising, but they urged that we need more studies with larger numbers of women.

Vaginal dryness & pain

Another meta-analysis of 10 clinical trials found that postmenopausal women who took phytoestrogen supplements had a small but statistically insignificant improvement in vaginal atrophy symptoms compared to women who took a placebo.

Overall takeaways

The largest and most comprehensive review (including 43 studies with over 4,000 total women) concluded that while there was some evidence that phytoestrogens improved hot flash and night sweats, many of these studies were too small and too short to produce solid results. These authors concluded that the evidence is not strong enough to recommend phytoestrogens.

It is difficult for researchers to decide whether phytoestrogens work because the clinical trials are so varied in their methods. Studies test different types of plants in different dosages and don’t control for other factors (e.g., how much phytoestrogens women might be consuming through foods outside of the study).

Overall, there is evidence that phytoestrogens may be helpful for perimenopausal women. It’s a therapy that may be worth a try, but there are no guarantees.

Side Effects, Safety, & Cancer Risk

Phytoestrogens are considered generally safe and do not pose side effects for most people.

Scientists have raised concerns that phytoestrogens could impact breast cancer risk by stimulating growth in estrogen-sensitive breast tumors.

Some research shows that phytoestrogens’ effects are not strong enough to have any real impact on breast cancer. Other research says this effect is still largely unknown for women with active breast cancer or a history of breast cancer.

In general, it appears safe for women with higher breast cancer risk to eat phytoestrogens at levels they would normally get in their diet. However, they should refrain from supplementing in higher doses until more research is available.

The Right Dose of Phytoestrogens

Most studies of phytoestrogens deliver the compound via supplements. While there is no official dosage recommendation, some researchers have recommended 40-50 mg of isoflavones per day to help with symptoms.

While taking phytoestrogens in a supplement form might seem easier, getting phytoestrogens through food has other benefits. Foods rich in phytoestrogens usually contain other powerful plant nutrients like omega-3 fatty acids, fiber, and antioxidants. The lower rates of hot flashes in Asian cultures are also linked to dietary phytoestrogens, not supplements.

Trying Out Phytoestrogens

Eating more phytoestrogens can be a fun way to rotate in new, healthy ingredients.

If you do start incorporating more phytoestrogens into your diet, make sure you give it some time. One study found that it took over 13 weeks for soy isoflavones to reach half of their maximum effect.

• Stir Fry or Bowl. Sauté extra-firm tofu with veggies, garlic, ginger, and soy sauce, or add noodles and make it a bowl.
• Baking. Substitute soy flour for wheat flour next time you make muffins. Add berries for a dose of lignans!
• Smoothies. Silken tofu can be added to smoothies instead of yogurt for a creamy texture. Add ground flaxseeds, too, for even more phytoestrogens.
• Snacks. Edamame (buy frozen, then steam) and hummus are easy isoflavone-rich bites.
• Beverages. Enjoy naturally sweet soy milk as a base for hot chocolate, café au lait, or golden milk.