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Mythbusting Soy - Part 1: Women’s Health And Hormones

From Switch4Good.org
October 2022

To set the record straight about soy's ability to improve women's health and help stave off breast cancer, we published this new blog post all about myth-busting soy in relation to women's hormones and overall wellness.

soy beans
Soy milk, edamame, and other soy products provide benefits, especially for women’s health.

Women’s Health and Hormones

It’s no secret that women run this world. Especially healthy, strong, energized women who are fueled by soy. Despite the bounty of misinformation out there, soy products like tofu, tempeh, soy milk, and edamame are incredibly beneficial for most people, and especially women. We’re addressing some of the big myths we’ve heard circulating about soy and women’s health, while debunking them with evidence. Soy shouldn’t be feared when its powerful compounds can vastly improve health in multiple ways. Instead, soy should be intentionally incorporated into a balanced diet to reap the many benefits. So grab your mother, sister, friend, etc, and enjoy a tofu taco, tempeh sandwich, or soy latte together- your health will thank you.

Soy beans, soy milk, and edamame
Soy milk, edamame, and other soy products provide benefits, especially for women’s health.

Myth #1: Soy feeds breast cancer.

According to the American Cancer Society, 1 in 8 American women get breast cancer (1). They note that what we choose to eat (and what we choose to avoid) affects this risk, and recommend putting more plants, and fewer animal foods on our plates (2). They specifically mention that “soy foods such as tofu may lower the risk of cancers of the breast” (2), which aligns with research on over 600,000 participants, showing that “a high intake of soy foods exhibits a beneficial role in reducing the risk of breast cancer.” (3)

What about dairy? Back in 2018, the American Cancer Society said that the jury was out on how cow’s milk affects breast cancer risk (2), but two years later, a groundbreaking study shed light on the issue. Research including over 50,000 participants revealed that people who drank more cow’s milk, regardless of the milk’s fat content, increased their risk of getting breast cancer by 50%. Replacing cow’s milk with soy milk, on the other hand, dropped their risk by 32% (4). As you can see, it’s extremely unfortunate that many women opt for cow’s milk over soy milk to lower their risk of getting breast cancer.

Some women who already have breast cancer also steer clear of soy milk out of fear that they’d be fanning the flames. Would they continue this practice if they knew that a leading national or global authority disagreed with them? What two highly reputable organizations agreed that soy is safe for breast cancer survivors? Three? The consensus was actually reached by five titans in this space: The American Cancer Society (5,6), the American Institute for Cancer Research (7), the World Cancer Research Fund International (8), and the Canadian Cancer Society (9). They all agree: Soy is safe for breast cancer survivors.

Not only is soy safe, large scale research shows that it’s protective! And the good news is it doesn’t take much to have an effect. A meta-analysis of 23 studies including more than 300,000 people found that adding the equivalent of ½ cup of tofu or a tall glass of soy milk to our daily diet drops the risk of dying from breast cancer by 24% (10). Given that breast cancer is the second leading cause of cancer death in American women, taking 1 in 39 lives (1), it makes sense to do what we can to protect ourselves and stay healthy. Including more soy in our diets is an excellent way to stack the odds in our favor.

Myth #2: Pregnant women should avoid soy, both for their own health, and for their babies too.

The debate over whether pregnant women should eat or avoid soy foods during pregnancy seems to be a particularly contentious topic. Thankfully, dedicated scientists have put years into studying this very issue, and their findings do a great deal to clear up the confusion.

Several recent studies have explored the connection between soy consumption during pregnancy and their risk of gestational diabetes (11), a condition where non-diabetic women develop high blood sugar during pregnancy, increasing the risk of complications for both mother and child (12). It turns out that, compared to pregnant women who eat less soy, those that have more of it dramatically cut their risk (13,14), and end up with less than half the odds of developing gestational diabetes due to better blood sugar control (15). Randomized controlled clinical research also found that, compared to a more animal-based diet, a soy-rich plant-based diet led to healthier blood sugar levels (16), indicating that replacing animal protein with soy may be responsible. Putting it all together, evidence is mounting that soy can support a healthier pregnancy.

It’s also become clear in recent years that, while soy was once rumored to cause birth defects, this myth has been put to rest. Instead, far more robust evidence now demonstrates that pregnant women who consume soy give birth to children with a lower risk of birth defects (11). Recent evidence also suggests that pregnant women who eat and drink more soy give birth to children with a lower risk of hyperactivity disorders and peer problems (17). In other words, soy intake is linked to benefits for both mother and child.

Edamame in their pods. Edamame is an easy and convenient way to enjoy soy.

Myth #3: Soy estrogens wreak hormonal havoc, disrupting menstrual cycles and causing hot flashes.

The idea that soy prevents ovulation is a mere myth. Though not medically concerning, soy consumption can slightly increase menstrual cycle length though, according to a recent review of over 400 reports (18). The paper, published by a team of international researchers, underscored that soy and its bioactive components don’t disrupt our hormones. They pose no problem to our thyroids, and “Adverse effects are also not seen on breast or endometrial tissue or estrogen levels in women, or testosterone or estrogen levels, or sperm or semen parameters in men.”

Not only is there no evidence of hormonal harm, the use of soy and its biologically active components to treat hot flashes has actually been of interest to scientists for 30 years (19). Consuming miniscule amounts of these components doesn’t have much of an effect (20), but it doesn’t take much to experience significant benefits. Nineteen randomized controlled trials, including over a thousand women, found that getting the equivalent of even half a cup of cooked soybeans per day provides enough of these helpful components to significantly reduce both the frequency and severity of hot flashes (21). In fact, a randomized controlled trial of postmenopausal women published last year found that switching to a healthy plant-based diet, including half a cup of daily soybeans, cut their number of hot flashes by 30% and their number of moderate-to-severe hot flashes by 42%, compared to people who continued with their usual diet (22). After three months of eating this way, the majority of women even reported becoming free from moderate-to-severe hot flashes, while none of the women eating their regular diet experienced this tremendous benefit. As a bonus, women who ate a plant-based diet with daily soybeans also improved their quality of life in the psychosocial, physical, and sexual domains, a true testament to the power of soy and other plant foods.


We hope this helps settle any fears about this powerful superfood. Looking for some meal inspiration? Try this quick Mexican Tofu Scramble. Pro tip: this recipe is an easy way to clean out your fridge and use up various veggies – the combinations are endless and sure to taste great!

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All-Creatures.org Health Position and Disclaimer

We began this archive as a means of assisting our visitors in answering many of their health and diet questions, and in encouraging them to take a pro-active part in their own health. We believe the articles and information contained herein are true, but are not presenting them as advice. We, personally, have found that a whole food vegan diet has helped our own health, and simply wish to share with others the things we have found. Each of us must make our own decisions, for it's our own body. If you have a health problem, see your own physician.