There is an ongoing debate on whether soy is harmful or beneficial for those suffering from PCOS. The proposed benefits 
of soy include improved cholesterol, decreased risk of cancer and 
improved menopausal symptoms among others. Yet, if you do an 
internet search for PCOS and soy and you will see many people
 confused about it, with some saying that soy is terrible for PCOS and
 should be avoided at all costs.

Soy is a plant food that is also a complete protein, meaning it has all the 
required amino acids. It is also low in fat, contains essential fatty 
acids, numerous vitamins, minerals, and fibre. Soy foods include soy
 milk and cheese, tofu, tempeh, miso, soy sauce, and edamame. Another form of soy, soy protein isolate, is often added to energy and 
granola bars and meat-alternative products. Soy protein isolate may 
contribute to oestrogen dominance commonly seen in PCOS.

More studies need to be conducted on soy
Soy in the form of soy protein isolate should be avoided for all women with PCOS. 
Women with PCOS who struggle with infertility, hypothyroidism, consume few calories
 or eat a poor diet may want to avoid or limit soy products.