What Are the Health Benefits of Soy for PCOS?

Poke bowl
Ivan Solis/Stocksy United

Many women with polycystic ovary syndrome (PCOS) are confused about whether or not soy is good for them. Some women even fear it.

This confusion, however, stems from inaccurate nutrition information on the internet about the health benefits or actions of soy. In fact, the research that is available has indicated that regular intake of small amounts of soy can actually improve female fertility and metabolic aspects of PCOS.

What Is Soy?

Unprocessed fermentable soy has been used as a diet staple by Asian countries for thousands of years. Soy is a plant food which contains all the essential amino acids, making it a complete protein source. Soy is low in fat, contains essential fatty acids, and is packed with vitamins, minerals, flavonoids, and fiber.

Soy is a phytoestrogen, meaning it can very weakly mimic estrogen and does not compare to the full strength of estrogen. Lab tests show that phytoestrogens in soy are approximately 100 to 1000-fold lower than that of estrogen. Soy, especially in small amounts (a few servings a week) has not been found to cause thyroid disorders. Soy is not harmful or evil for that matter, for women with PCOS. 

Health Benefits of Soy

Soy has been shown to provide many health benefits. These include relief of menopausal symptoms like hot flashes, prevention of breast and prostrate cancer, reduction in bone turnover and reducing the risk for osteoporosis, and prevention of heart disease.

In 1998, the FDA issued a food claim stating that "diets low in saturated fat and cholesterol that include 25 grams of soy protein a day may reduce the risk of heart disease." 

Food Sources of Soy

Since the FDA ruling, there has been a large increase in the amount of soy products sold in the U.S. Many of these foods are from processed soy, and not the tradition unprocessed, fermented soy typically used in Asian cultures such as tempeh or miso. 

Health benefits of soy are believed to come from unprocessed soy. Processed types of soy have been associated with negative health implications such as affecting thyroid function.  Soy protein isolate along with hydrogenated soybean oil, for example, is often added to energy and granola bars and meat-alternative products. These forms of soy are processed. Checking the ingredient list on food labels will help you to know what form of soy if any, are in your foods. Here are some examples of processed and unprocessed sources of soy:

Unprocessed Food Sources of Soy

  • tofu
  • natto
  • tempeh
  • miso
  • soy sauce
  • edamame
  • soy nuts

Processed Food Sources of Soy

Health Benefits of Soy for PCOS

While the research about soy intake for women with PCOS is limited, the results are showing soy can improve many metabolic aspects of PCOS. These include reducing total and LDL (the “bad” cholesterol), triglycerides, inflammatory markers, blood pressure, and insulin.

Soy intake has also been shown to reduce testosterone and be protective against oxidative stress.

A study published in Journal of Clinical Endocrinology and Metabolism randomized 70 women with PCOS into two groups to take either 50 mg/d soy isoflavones or a placebo for 12 weeks. Metabolic, endocrine, inflammation, and oxidative stress markers were established at the beginning of the study and at the end of the trial. 

Compared to the placebo group, those who received soy significantly decreased their levels of insulin. Supplementation with soy resulted in significant reductions in free androgen index and triglycerides compared to the placebo group. 

Other studies investigating the use of soy in women with PCOS found that soy improved total and LDL cholesterol.

Soy and Fertility

While there aren’t any studies that look at how soy may impact fertility in women with PCOS, there are studies that have looked at soy use in infertile women. 

A study published in Fertility and Sterility looked at the relation of soy phytoestrogen intake in 315 women undergoing infertility treatment with assisted reproductive technology (ART) at Massachusetts General Hospital. This study found that soy not only improved the fertilization rate, but the rates of pregnancy (52 percent vs. 41 percent) and live births (44 percent vs. 31 percent) were higher in women who ate soy compared with those who did not eat soy. Women with the highest amount of soy intake had significantly higher odds of live births than those with the lowest intake.

Tips for Incorporating Soy Into Your Diet

  • Choose unprocessed, non-GMO soy foods
  • Avoid eating large amount of meat alternative foods
  • Avoid foods that contain soy protein isolate or hydrogenated soybean oil
  • Use firm tofu or tempeh in place of meat in stir-fries
  • Make smoothies using soy milk and silken tofu.
  • Enjoy edamame as a snack or toss into salads or noodle dishes
  • Add grilled tofu to a salad
  • Enjoy soy nuts as a snack
  • Use soy nut butter in place of peanut butter.
  • Add miso or soy sauce to flavor dishes 
  • Add tofu or tempeh into a sandwich or wrap 


Chavarro JE et al. Soy Intake Modifies the Relation Between Urinary Bisphenol A Concentrations and Pregnancy Outcomes Among Women Undergoing Assisted Reproduction. J Clin Endocrinol Metab. 2016 Mar;101(3):1082-90.

Jamilian M. The Effects of Soy Isoflavones on Metabolic Status of Patients with Polycystic Ovary Syndrome. J Clin Endo Metab. 2016;101:0000.

Khani B et al. Effect of Soy Phytoestrogen on Metabolic and Hormonal Disturbance of Women with Polycystic Ovary Syndrome. J Res Med Sci. 2011;16:297–302.

Romualdi D et al, Is There a Role for Soy Isoflavones in the Therapeutic Approach to Polycystic Ovary Syndrome? Results from a pilot study. Fertil Sterility. 2007.

Sathyapalan T. The effect of Soy Phytoestrogen Supplementation on Thyroid Status and Cardiovascular Risk Markers in Patients with Subclinical Hypothyroidism: A Randomized, Double-blind, Crossover Study. J Clin Endocrinol Metab. 2011 May;96(5):1442-9.

Continue Reading