Is soy bad for PCOS?
I see many women, especially with PCOS, fear soy due to phytoestrogens, thinking it will raise their estrogen levels or even increase their risk for cancer.
There is a lot of misinformation and generalization going on out there, so today I want to clear things up!
What are phytoestrogens?
Phytoestrogens are plant compounds that act as modulators in the body, meaning they have both estrogenic & anti-estrogenic effects.
They are not the same as our own estrogen.
Where do we find phytoestrogens?
Soy is a rich source of phytoestrogens however these plant compounds are also found in other foods such as flaxseeds, dried fruits, sesame seeds, garlic, peaches, berries, oats, alfalfa, apples, carrots, wheat bran, coffee, tea, cruciferous vegetables….
What about external sources of estrogens?
All animal products contain traces of estrogen because even male animals produce the hormone. Many farms give female animals, especially cows, high doses of estrogen to increase the amount of milk they produce. Eating these products may increase a person's estrogen levels, particularly dairy products.
In addition, the majority of soy (over 70% in the U.S) is used to feed livestock, especially poultry and pigs. Not only is this impacting the planet but it is also impacting our health. What the animal we are eating ate before us matters.
Soy, and particularly GMO soy, is not the natural food for these animals and this increases the omega 6 fats in the meat we then buy which raises inflammation by creating an imbalance between omega 3 fatty acids and omega 6 fatty acids.
Many of these animals get sick and then need high doses of antibiotics, which we are also exposed to. This has a major impact on our gut which can deplete our good microbiome, so essential for keeping us healthy.
Then we have xenoestrogens from the chemicals in our cosmetics, body products, cleaners, pharmaceuticals, packaging, food…
These are are estrogen-mimicking compounds that are not produced by our body and commonly defined as endocrine-disrupting chemicals (EDCs). EDCs pose a serious health concern since they may cause a wide range of health problems, starting from pre-birth till adult lifelong exposure.
According to the World Health Organization (WHO), EDCs are suspected to be associated with altered reproductive function in males and females, increased incidence of breast cancer, abnormal growth patterns and neurodevelopmental delays in children, as well as changes in immune function. EDCs may include chemicals like BPA, BPS, parabens, and more.
Benefits of phytoestrogens
Phytoestrogens buffer estrogen levels in the body and they can promote the healthy metabolism of estrogen in the body.
As modulators of estrogen, this means they can either raise estrogen levels (commonly seen in menopause when estrogen levels drop) or lower estrogen levels (most often in premenopausal women when estrogen levels are higher) (1).
The effects of phytoestrogens in the body will largely depend on the person and different factors such as age, quality and quantity consumed, health status, and even the state of your microbiome.
In women of reproductive age, phytoestrogens have more of an anti-estrogen effect because they out-compete our own stronger estrogen known as estradiol.
This is why they can help to improve symptoms such as PMS and making periods lighter by improving estrogen levels in the body.
In post-menopausal women, phytoestrogens can have more of a pro-estrogen effect because estrogen levels naturally decline once the ovaries have shut down. This can promote a mild estrogenic effect in menopausal women which can help to improve symptoms of low estrogen such as hot flashes, insomnia, and vaginal dryness.
Benefits of soy for PCOS and fertility
Phytoestrogens can have many potential health benefits including lowering cholesterol, regulating the menstrual cycle and ovulation, improving menopausal symptoms, and decreasing the risk of osteoporosis, heart disease, and even breast cancer.
And what about PCOS?
A study showed soy intake in PCOS women to decrease markers of LH, TGs, LDL, DHEA-S and testosterone after 3 months (2).
Another study showed the administration of soy isoflavones to significantly improve markers of insulin resistance, BMI, hormonal status, triglycerides and biomarkers of oxidative stress after 12 weeks (3).
And another study in over 200 women who were receiving IVF treatments showed that those who took 1,500 mg of soy phytoestrogen a day had higher rates of implantation and pregnancy compared to those who did not take soy (4).
Soy is a complete source of plant-based protein and can provide many health benefits, especially if eaten as an alternative to foods like red meat and processed animal products.
The benefits seem to outweigh the risks when it comes to soy consumption however this is if you choose quality soy products and moderate consumption.
Soy is a common allergen thus not everyone does well with it but if you do tolerate soy stick to moderate amounts and always choose organic and fermented soy. My favourite ways to consume soy are organic tofu, edamame, tempeh, miso, and tamari.
But what about breast cancer?
Many studies have shown that soy and isoflavones intakes can have a protective effect on postmenopausal breast cancer (5).
In addition, several reports indicate that the occurrence of breast cancer is lower in Asian individuals compared with other populations due to the inclusion of isoflavones as a regular part of their diet. This also may be influenced with early exposure to soy starting as early as childhood in Asian cultures (6)(7).
However, it’s important to remember that the quantity and quality of soy intake matters, and can greatly influence the effects of phytoestrogens on the body.
What to look for
Always buy organic! Soy is the number one genetically modified crop in the world -90% of soy sold in the US is GMO and at least 60% of the soybeans grown in Canada are GMO. You can avoid GMOs by buying certified organic food.
Choose fermented - this reduces the phytic acid and lectin levels in soy helping to improve absorption, increase nutrient availability, and reduce irritation in the gut. As it is fermented it also provides beneficial bacteria for our gut microbiome. Fermented soy products include tamari, miso, natto, and tempeh.
What to avoid
Avoid conventional animal products (opt for grass-fed/pasture-raised/free-range), soybean oil, soy flour, soy protein, soy isolate, soy milk, soy concentrate, and vegan junk food made from soy. These are all highly processed and genetically modified and so are not healthy forms of soy.
Disclaimer: Information on this site is intended only for informational purposes and is not a substitute for medical advice. Always consult with a healthcare provider before implementing changes. Read additional disclaimer info here.
Resources
https://academic.oup.com/jcem/article/=Phytoestrogens%20are%20a%20group%20of,polycystic%20ovary%20syndrome%20(PCOS).
https://www.ncbi.nlm.nih.gov/pubmed/29468748
https://www.ncbi.nlm.nih.gov/pubmed/27490918
https://www.ncbi.nlm.nih.gov/pubmed/22091248
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3214337/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3214337/#:~:text
https://www.usda.gov/sites/default/files/documents/coexistence-soybeans-factsheet.pdf