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?
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.
At 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
We 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!