Soy products have gotten a bad rap in the past decade. There is a ton of misinformation surrounding soy products (like tofu and soy milk), especially regarding how this food affects hormones in both men and women. I’m here to debunk some common myths about soy products!

This post will cover:

Soy’s reputation and why people think it’s bad for you
What the research actually shows us
Health benefits of soy (for both men and women!)

What is soy and where can I find it?

Soybeans are legumes that have been cultivated for thousands of years, particularly in Asian cultures. Today, they’re found in a variety of forms, including:

Whole soy foods: Edamame, tofu, and soy milk.
Fermented soy: Miso, natto, tempeh, and soy sauce.
Processed soy products: Soy protein isolate (often used in protein bars and shakes) and soy-based meat alternatives.

Whole foods and fermented sources of soy are amazing sources of quality protein, fiber, and micronutrients. They’re also rich in isoflavones, which are phytoestrogens. A phytoestrogen is a plant compound that mimics estrogen in the body, but at a much weaker level than true estrogen. This is where much of the fear around soy products comes from. Because of its rich isoflavones, soy has been mislabeled as an endocrine-disrupting food. People read the word “phytoestrogen” and start to think it’s going to mess with their hormones.

Here’s how isoflavones in soy actually function and what it means for both men and women:

1. Soy isoflavones are weaker than human estrogen

Phytoestrogens are far less potent than your body’s own estrogen. Their estrogenic effects are about 1/1,000th the strength of human estrogen. So yes, they “act like estrogen”, but at a much weaker level.

2. Soy isoflavones have dual actions

Phytoestrogens can bind to estrogen receptors in the body, but they don’t always act like estrogen. Depending on the tissue and hormonal environment, they may:

Mimic estrogen when levels are low (e.g., during menopause or in other cases of low estrogen), or
Block stronger, potentially harmful estrogens when levels are high (e.g., in estrogen-dominant conditions, like endometriosis).

How does soy affect women?

Basically, phytoestrogens have this funny way of helping to even out estrogen levels when they’re either too high or too low. They bind to our estrogen receptors to create a small estrogenic effect when we need it (i.e. when we have super low estrogen) and they also block the effects of other harmful estrogens that can lead to cancerous conditions or other issues.

Here’s a quick summary below:

Hormone Balance: Phytoestrogens can help regulate estrogen activity, making them useful for managing estrogen-dominant conditions like PMS, PCOS, or endometriosis.
Breast Cancer Protection: By blocking stronger estrogens, soy’s phytoestrogens have been shown to reduce the risk of hormone-sensitive cancers.
Menopause Relief: During menopause, phytoestrogens offer mild estrogen-like support, alleviating symptoms such as hot flashes and preserving bone health.

Have more questions about how what you eat affects your hormone health? Book a free, 15-minute connection call with me and let’s chat.

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How does soy affect men?

One of the most common myths is that soy’s phytoestrogens might “feminize” men or lower their testosterone levels. The latest research shows this is not the case:

No Testosterone Impact: Large-scale studies and meta-analyses consistently demonstrate that soy consumption has no adverse effect on testosterone levels or sperm quality in men.
No Feminizing Effects: The weak estrogenic effects of phytoestrogens are not strong enough to impact male hormones or cause physical changes.

So relax boys — soy milk will not give you boobs! It’s estimated that a man would need to eat around 14-20 servings of tofu every day even to approach the estrogen levels that could theoretically cause changes in hormone activity. And I say theoretically because this has never been scientifically shown in humans. You would need to eat over 2 kilograms (4.5 pounds) of tofu daily to potentially see these changes. If you’re including soy as part of a balanced whole-foods diet, then you’re not even close to that amount (one healthy serving is about 0.19 pounds of tofu).

FAQ: “How can soy have a positive effect on women’s hormones, but not have a negative effect on men’s hormones?”

The key here is understanding how phytoestrogens interact with the body.

Phytoestrogens are selective estrogen receptor modulators (SERMs). This means they can bind to estrogen receptors in the body, but their effects depend on the existing hormonal environment and the type of tissue they interact with.

For women, phytoestrogens can help balance hormones by either mimicking estrogen when levels are low (e.g., during menopause) or blocking stronger estrogens when levels are high (e.g., estrogen dominance). This balancing effect supports overall hormone health without overwhelming the body in either direction.

For men, soy’s weak estrogenic activity isn’t strong enough to override testosterone. The body’s natural hormone regulation ensures testosterone levels remain stable, and phytoestrogens don’t compete effectively enough with male hormones to cause negative changes.

Soy adapts to the body’s needs, and this adaptability is why its effects differ between men and women. Duality, my friends! Two things can be true at the same time.

Science-backed benefits of soy

Soy is actually an incredibly versatile and nutrient-dense food that should be rotated into a balanced diet, whether you’re eating meat or not. Here’s a summary of the benefits of soy:

High-Quality Protein: Soy is a complete plant protein, containing all nine essential amino acids, making it excellent for creating enzymes to fuel your metabolism, building muscle, and creating neurotransmitters and hormones for good brain/mental health.

Heart Health: Soy protein can help lower LDL (“bad”) cholesterol and support cardiovascular health, especially for those at risk for cardiovascular disease. Some studies have shown that regular consumption of soy products can help lower cholesterol by up to 30%.

Bone Support: The isoflavones in soy promote bone density and reduce the risk of osteoporosis. This is especially important for women going through menopause.

Rich in Nutrients: Packed with fiber, iron, calcium, magnesium, and potassium to support energy, the nervous system, immunity, and strong bones.

Anti-Inflammatory Properties: Whole soy foods can reduce markers of inflammation, benefiting cellular health and preventing chronic diseases. It’s important to choose organic and non-GMO sources of soy to reduce potential inflammatory risks from chemical exposures (like glyphosate and other herbicides — these are often sprayed on GMO soy crops).

Hormone Health: For women, soy’s phytoestrogens can help regulate estrogen levels and ease menopause symptoms. For men, soy provides the above benefits without impacting testosterone or fertility. Win-win.

The bottom line

Stop listening to people who tell you soy is bad for your hormones. If they were reading the current research and valued evidence-based care, they wouldn’t be telling you this. They’re likely just following a trend or stuck in their narrow view of thinking! At first glance, I can completely understand why the word “phytoestrogen” would raise concerns. But the research tells a different story, so let’s leave those myths behind and enjoy soy products for all their amazing benefits.

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