Soy food

Is soy bad for endometriosis?

Endometriosis affects 1 in 9 Australian women, in fact, this may be an underestimate as many women remain undiagnosed. It can be extremely painful and debilitating and can lead to infertility. It is no wonder women with endometriosis are looking at all management strategies to assist their symptoms.


Soy foods are one of the most talked about foods when it comes to endo management and it’s not as simple as you may think! Read on and we’ll help explain the link between soy and endo.



Soy food



What is endometriosis?

Endometriosis is when tissue that is found lining the uterus, grows in other areas of the body such as the fallopian tubes, ovaries, abdominal cavity etc. Just like the the tissue that lines the uterus, endometriosis tissues also respond to hormones released in the body, resulting in bleeding. In time this leads to inflammation, scarring and painful adhesions.


Is there a cure?

There is currently no cure for endometriosis and management may be a mix of pain management, medication, surgery to remove the endometriosis and hormonal therapy (Dunselman et al. 2014). However, dietary management is gaining traction. There is now a significant and growing body or research looking at how diet may impact the symptoms of endometriosis. Soy is often a topic of discussion when it comes to diet. So why?



What is soy?

Soy foods come from the soy bean (aka edamame). Soy foods include tofu, tempeh, soy sauce, miso, soy milk, soy-based yoghurts and more recently, the wide variety of soy-based meat alternatives e.g. soy burger patties.


Soy foods are actually quite nutritious! They are a complete protein, meaning that they contain all amino acids (rare for plant-based proteins!). They are also a great source of fibre, iron, magnesium, potassium and sometimes calcium (depending on how the product is made).


What about soy and endo?

What’s the problem?

Soy contains a type of antioxidant called phytoestrogens. Due to the structure of phytoestrogens, some propose that they can mince the effect of oestrogen in the body and have been linked to many oestrogen-depended conditions (such as endometriosis). Oestrogen-dependent just means that oestrogen must be present for the condition to develop.


So is soy good or bad for endo?

Some animal-based studies and case reports (smaller and low quality studies) have found that oestrogen supplementation may lead to worsening for symptoms (Chandrareddy A, 2008).


However, more recent, higher quality research is finding the opposite effect. In humans soy products may actually help to improve symptoms of endometriosis (Youseflu S, 2020 & Tsuchiya M et al, 2007)


It seems that there are lower rates of endometriosis in countries that consume the highest amounts of soy foods (Tsuchiya M et al, 2007). It seems that the phytoestrogens in soy actually has an anti-oestrogen effect, meaning that they block the oestrogen from binding to it’s receptors.


So rather than reducing soy for endo management, we recommend increasing your intake!



How to include more soy into your diet


  • Try scrambled tofu rather than scrambled eggs

  • Add edamame to your avo on toast


  • Steamed edamame with soy sauce

  • Marinated tofu skewers

Main meals:




Chandrareddy A, Muneyyirici-Delale O, McFarlane S, Murad O. 2008. Adverse effects of phytoestrogens on reproductive health: a report of three cases. Complement There Clin Pract.


Dunselman G, Vermeulen N, Becker C, Calhaz-Jorge C, D’Hooghe T, De Bie B et al. 2014. ESHRE guideline: management of women with endometriosis. Human Reproduction 29:400–12.


Tsuchiya M, Miura T, Hanaoka T, Iwasaki M, Sasaki H et al. 2007. Effect of soy isoflavones on endometriosis: interaction with oestrogen receptor 2 gene polymorphism. Epidemiology. doi: 10.1097/01.ede.0000257571.01358.f9.


Youseflu S, Sadatmahalleh S, Mottaghi A, Kazemnejad A. 2020. Dietary Phytoestrogen Intake and The Risk of Endometriosis in Iranian Women: A Case-Control Study. Internation Journal of Fertility and sterility.

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