The Truth About Soy

Clients often tell me that they're confused about phytoestrogens, and whether it's ok to eat soy or not.

They might have heard claims that 'soy gives men man-boobs' or they're worried about consuming phytoestrogens if they have a condition of estrogen dominance (such as PCOS or endo). 

With so much conflicting information online, it can be hard to know what's true and what's not.

So what does the science say about phytoestrogens, and should you avoid soy?

Let's start by looking at what phytoestrogens are.

Soy is a phytoestrogen. Phytoestrogens are compounds, found in certain plants, that can have estrogenic effects (meaning, they act like estrogen) in the body. 

It's important to note that they are different from xenoestrogens; phytoestrogens are natural (found in plants), whereas xenoestrogens are man-made chemicals that can activate estrogen receptors in the body.

But, if phytoestrogens also act like estrogen in the body, then, aren't they also bad? 

The short answer is: No, because that's not how they work. But first we need to understand more about estrogen.

There are estrogen receptors all over the body (this is one of the reasons we know estrogen must be so important in the body, affecting many different organs and processes). 

These receptors are kind of like a lock, and estrogen is the key that 'stimulates', or activates, them.

There are two types of receptors: alpha and beta. Beta receptors are found in the brain, bones, heart and blood vessels, bladder, breasts, ovaries, and womb, while alpha receptors are only found in the breasts, ovaries, and womb.

We want estrogen 'stimulation' in the heart, bones, and brain, as it has positive health effects, but we don't want too much estrogen activity in the breasts, womb, and ovaries, as this may cause cells to proliferate and mutate, increasing the risk of cancer in these areas.

Ok, so here's the cool part. 

Phytoestrogens stimulate the beta receptors (which we want), but they actually block the alpha receptors (kind of like gum in the lock), preventing xenoestrogens from locking into these receptors. (Incidentally, this mechanism is also how the new class of SERM (selective estrogen receptor modulators) pharmaceutical drugs work, which have been developed for menopausal women. Luckily, we have something in nature that does this exact thing!)

Isn't nature amazing?

So phytoestrogens help to prevent cancers in the breasts, ovaries and womb, whilst providing us with estrogen where we need it (which is especially important when estrogen levels drop, such as in menopause). 

Phytoestrogens also stimulate sex hormone binding globulin (SHBG) which controls and regulates levels of hormones, like estrogen, by binding hormones, stopping them from building up in the body.

So, should we be scared of phytoestrogens? No, not at all! And in fact, they can be extremely beneficial for menopausal women.

What about soy, specifically? 

I believe some of the concerns about soy are specifically about GM soy (which may cause inflammation and other health issues for some people). That's not so much of an issue here in the UK and Europe, where it's very easy to find non-GM soy (but you can always opt for organic soy products if this is a concern for you). Another separate issue is that most of the soy we eat in the West is in a highly processed form (such as soy protein isolate, soy fake meats, and it's an additive in many processed foods). Processed food in general is not good for our health, and may contribute to health problems. It's always best to eat food as close to its natural, whole form as possible. In the case of soy this would be tofu (which is minimally processed), tempeh, miso, edamame beans, and even soy milk (as it's made from whole soybeans).

Soy isn't the only type of phytoestrogen, however.

All pulses contain phytoestrogens - chickpeas, lentils, etc. - and we know that beans and pulses are one of the healthiest foods on the planet, providing a great source of fibre and contributing to good gut health and weight loss/management. Flaxseeds (linseeds) are another great source of phytoestrogens, which also increase our fibre intake.

Each of these foods provides a different type of phytoestrogen (there are three: isoflavones, lignans and coumestans), which each provide different health benefits, as well as in varying amounts. So we want to make sure we're eating a range of different phytoestrogens, and not just relying on one source.

Since legumes and pulses are so important for overall health and longevity, aim to have at least one portion of pulses per day (which includes a good quality form of soy, such as tofu, tempeh, or miso, at least twice a week). In addition, if you're perimenopausal try adding 1-2 tbsp ground flaxseed every day (if you are not yet perimenopausal and still have a cycle, I really recommend 'seed-cycling' - more on this in a future post!).

If you're perimenopausal and looking for more tips on how to navigate this rite of passage using nutrition and other tools, check out my webinar on 'Thriving in the Menopause', where I cover phytoestrogens and more. 

If you're looking for more personalised nutrition advice, book in for a free consultation to discover how coaching could help.

Do you eat soy? Are beans a part of your diet, or do you struggle with them? Let me know in the comments below!