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Should You Include Soy in your PCOS Diet?

This is one of the questions that I get again and again. Should soy be a part of your PCOS diet? There is so much conflicting information out there – some touting soy as an essential element to your diet, whilst others steer clear of it completely.

Well. Let’s have a look at the evidence behind soy and whether or not we should be including it in our diets.

What’s the deal with soy?

Let’s have a look at why soy is so controversial. The thing with soy is that it is rich in phytoestrogens (1). These are plant-based estrogens that bind to the estrogen receptor in the body, causing estrogen levels to rise or fall (2).

So, is this a good or bad thing?

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Estrogen in PCOS

Well, before we get into whether or not soy would be helpful as a part of your PCOS diet, we need to understand what our estrogen levels are doing. To do that, we need to know a little bit more about the menstrual cycle.

Should-soy-be-a-part-of-your-pcos-diet-fertilityAt the start of the menstrual cycle, the pituitary gland releases two hormones (follicle-stimulating hormone and luteinizing hormone) which causes the ovary to produce estrogen to stimulate the development of follicles to ultimately release the egg.

If for whatever reason, the egg is not released, as is the case in PCOS, the follicle forms a cyst and more estrogen is released to develop more follicles. This leads to estrogen dominance (3)

So, we tend to have higher levels of estrogen in the body already.

What happens when we add phytoestrogens to the mix? Let’s have a look at the research relating to the impact on soy on various systems.

Soy and your Cholesterol levels

Should soy be a part of your pcos diet soyWe know that women with PCOS tend to have higher cholesterol levels, as part and parcel of the syndrome. So, researchers have studied the effect of soy on cholesterol levels in women with PCOS. You may be surprised by what they found. They found that soy intake reduced levels of low-density lipoproteins (LDL’s). This is the “bad” cholesterol. So, that should be good news, right?  Well, there were no other improvements in any of the other metabolic markers of PCOS so very few of the symptoms that bother us were improved (4)

Soy and your Thyroid

Research has shown that soy has a potentially goitrogenic effect, particularly if you are iodine deficient (5). Now, this is important because many women with PCOS also struggle with thyroid issues and incorporating soy into your diet may make your thyroid symptoms worse.

Soy and Infertility

This one is a big one for me. Researchers have found that soy intake can disrupt ovulation. (6). Now, I want to be clear about something. Researchers were looking at the effects of soy on healthy adult women. Ie: women without PCOS.

So, if soy can disrupt ovulation in healthy women, what will the impact be on someone with PCOS who struggles with ovulation anyway?

Let’s wrap it up and put a pretty bow on this discussion.

How soy affects PCOS:

  • Women with PCOS tend to be estrogen dominant.
  • Soy contains phytoestrogens and can influence estrogen levels in the body.
  • Soy can lower your levels of LDL BUT it can also make your thyroid issues worse and further delay ovulation.

The question for me, then, is: Do the benefits outweigh the possible harm caused by soy? I would say, NO!

You can find other ways to lower your cholesterol levels naturally, by improving your insulin sensitivity and lowering your testosterone levels (but that’s an article for another day).

I really wouldn’t want soy-based products to interfere with my ovulation, especially if I was trying to conceive.

And that is why I DO NOT recommend including soy in your PCOS diet.

I would love to hear from you, whether you agree or disagree. Please leave me a comment below!

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Tarryn Poulton

Tarryn Poulton

Tarryn Poulton is a PN1 Certified Nutrition Coach and PCOS expert who has been a leader in the online PCOS space for over 8 years. Tarryn has the support of leading clinicians from around the world who support her scientific approach to understanding and talking about PCOS this includes all medical journals and ongoing research. You can read more about Tarryn and the team here.

19 Responses

19 Responses

  1. This article couldn’t have come at a better time. I went for blood tests this morning as I have been struggling with breast pain for weeks (I normally get this for just a day or two before my period which was diagnosed as estrogen dominance).
    Recently I have been consuming pretty large quantities of soy beans in order to up my protein without consuming more meat (bad for the environment) or whey protein (trying to cut out dairy)

    Looks like I need to find a different protein source.

  2. My PCOS isn’t traditional in that my estrogens are actually low, so my doctor/nutritionist advised me to eat soy – preferably organic, non-GMO and fermented. I seem to be doing fine with it!

  3. Hello,

    I have to say, I was diagnosed last year with Polycystic ovaries, I went because my periods was all over the place, (I was vegetarian at the time) when my doctor advices me to eat meat, with adding exercise daily. I didnt really want to go back to eating meat., but none the less, I agreed, I lost 8 lbs, yay! I know, but my periods went from 6 weeks to 8 weeks, and more a less no existent.
    Then I came across a program of a plant base diet, and the health benefits of it, (nothing to do with pcos) so over night I switched, 16 Jan this year, My diet consists of soya products in nearly every meal, 7 months down, 7 periods, every 30 days, my periods haven’t been like this for well over a year. Switching to a vegan diet, has changed everything, best decision I ever made…..

  4. For me it’s not an option as I’m allergic to soy. The amount of products that have some form of soy is super high. (Since it’s a protein allergy I don’t avoid the oil and lecithin as much but I do limit the amount of soy oil I consume.)
    I find that I don’t really miss it, there are substitutes that I use like coconut aminos instead of soy sauce (bonus – it’s not very salty!) And I’m avoiding a lot of processed food which is healthier anyway!

  5. I avoid processed soy. I have one serving of either tofu or tempeh. I make sure they are non gmo. My doctor and my naturopath both agree that these two types of soy are ok in moderation. Being vegan, it is an essential source of nutrients.

    1. Hi, I’m vegetarian and am reading about soy and dairy. I am ok with stopping dairy but I’m worried about soy. I feel like I still need it for a balanced diet. Could you explain which soy is ok? Is soy milk out?
      Thanks
      Steph

  6. Hi Tarryn
    Thank you for sharing. I think it will be good to take into consideration that traditionally women in Asia consume a lot of soy products but always in fermented form (like tofu, soy sauce), non GMO and in SMALL amounts. Somehow they don’t have big issues with estrogen dominance. Probably like everything the amount and quality is the key. Definitely Big NO, NO to commercially produced soy milk, soy isolated and non-fermented soy beans etc. I don’t think a little bit of soy in sushi or Tofu once a month will be a big issue as I have tested that so many times and no ‘side effect’. 🙂 I n fact I was eating fermented soy regularly when I got pregnant with policystic ovaries few years ago. Obviously finding a good organic non GMO soy isn’t always easy but possible:) It will be also a good idea to find out about research explaining why fermented soy is different than non-fermented. All best, A

  7. Hi, I’m interested to know where you got your research from. As there is only 5 published studies, investigating soy use in women with PCOS, the research is overwhelming favorable for its use in improving metabolic aspects. None of the studies showed any ill-effects of soy use among women with PCOS.

  8. Hi, I have a question in regards to soya. I don’t have it at all. I know things really aren’t good if they are completely soya based like milk or soya cheese replacements etc. But I am finding so much of the GF DF options contain soya. I will still continue to avoid them but my question is how bad is it in comparison to gluten and dairy. If I were to go to a restaurant do I really need to say soya free too (this is such a headache!! Not chinese of course though!). I’m off on holiday with all the extended family soon and again I can easily managed GF DF but soya just makes it almost depressing…. can I have it in smalls amounts if it is a small part of the ingredients in a product rather then the main ingrendients and if it is on the rare occaion or should I completely avoid it like gluten and dairy. I’ve just noticed a lot of women on the PCOS group still have it whilst maintaing and GF DF diet. PLEASE HELP!!! I just need to be told if its an all out or this is ok on small, rare occasions.

  9. What is your opinion on processed soy vs non-processed soy in the above?

    All the clinical studies done that I am aware of concerning soy and it’s phytoestrogens is based off of processed soy. Which we already know, anything processed is not something good or healthy for our bodies.

    There is no studies however that I have found on non-gmo and/or organic soy products. I personally have never seen a dip or rise in my estrogen levels in the past year of taking in this kind of soy, but I avoid the processed ones like the plague.

    Thoughts?

  10. It depends on your individual PCOS hormone levels. I was testosterone dominant and my specialist adviced a Plant based diet. High in Soy:soya. Since this my acne has gone and periods returned. Plus hair is thicker and no longer have high cholesterol. Also for comparison there is LESS hormones including estrogens in soya than there is on dairy milk. This article is one sided and doesn’t offer a balanced comparisons to alternatives. I advise people to do their own research based on their individual condition and blood levels…. I also recommend coconut milk and coconut milk yogurts less calories and still all nutrition

    1. I completely agree – I’ve read elsewhere that the plant oestrogen *can*help lower our oestrogen. I am also on a plant based diet and my skin has improved no end.

  11. I am so glad I found your website. I was diagnosed with PCOS at 19, given a prescription for birth control, and sent on my way. I came across insulin resistance and PCOS information when I was 25. And cut almost all added sugar from diet. I was able to get off birth control, soon afterwards.
    That diet change has helped me until these last five years. I’m been tried, have no energy. I can barely make it through the work day, much less come home and clean.
    I am 47, and plan on making a lot of changes.
    I was recently diagnosed as a Diabetic, and have hypertension.
    My doctor also found three undiagnosed heart murmurs.
    My cholesterol is very good.
    Buy my weight has increased since I’m not as active.Five years ago, I walked 17 miles a week. I’m hoping that these changes will have me back to walking and a less cluttered house.

  12. I have stopped consuming dairy products in the last 4 months and I had started with soy milk. I stopped that as well as my acne kind of got worse. And my mom continues to use soy flour mixed with wheat flour. So should I avoid soy?

    1. There are many other options for gluten free flours even that don’t include soy. It’s best to avoid it entirely. Even in baked goods. As you said your acne is getting worse. that’s enough reason to omit it. Some people can even be sensitive or allergic to certain foods and cause similar inflammatory reactions so either way best to cut it the food item out.

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