soy and pcos diet

Soy and PCOS

Have you heard conflicting information about which foods you need to avoid with polycystic ovarian syndrome (PCOS)? Soy is particularly controversial in the PCOS community with some praising its benefits and others claiming it could be bad for your health. 
This article will review food sources of soy, explain what the research says about soy and PCOS, and share our stance on this topic at Root.

What is Soy?

Soy comes from a soybean plant, which pods produce a type of legume. Like other legumes, soy is a nutrient-dense source of plant protein. In fact, one cup of shelled edamame (immature soybeans) contains 19 grams of protein and 8 grams of fiber! Soybeans are also rich in important nutrients for women like iron, magnesium, folate, and vitamin K (1).

Food Sources of Soy

  • Soybeans
  • Edamame
  • Tofu
  • Soy Milk
  • Tempeh
  • Miso
  • Natto
Soy is eaten in many different forms. The least processed forms of soy include soybeans (brown or tan in color) and edamame (immature soybeans that are green in color). Foods like soy milk and tofu are made by soaking and grinding soybeans into either a liquid or pressed block. Some soy products, like tempeh, miso, and natto, are made by fermenting soybeans. These fermented options are particularly popular in Asian cuisine.

However, manufacturers often use other types of soy-based additives in packaged food products like soybean oil, soy lecithin, and soy protein isolate. These types of foods are less healthy because many of the natural nutrients found in soy have been stripped and processed away. 

Why Do Some Recommend Avoiding Soy?

Like other common foods, some people may develop a food sensitivity to soy. This isn’t necessarily related to the food itself, but rather the health of your gut and overall immune system. We may recommend short-term elimination diets, when indicated, to assist in healing the gut, reducing inflammation, and improving food tolerance.
Growing conditions is another concern for consuming soy. More than 90 percent of the soy grown in the United States is genetically modified (2). These GMO crops are sprayed heavily with a weed-killing chemical called glyphosate (i.e. Roundup) that may affect reproduction, hormone balance, and the gut microbiome (3, 4, 5).  You can easily reduce and/or eliminate glyphosate residue by only choosing organically grown soy.
Lastly, soy contains higher concentrations of isoflavones, a phytoestrogen that has similar functions to human estrogen but with much weaker effects. A diet excessively high in soy may lead to hormonal imbalances in certain cases. However, when combined with a balanced and varied diet, the level of phytoestrogens present in most soy foods is not likely to cause hormonal disruption (6). In fact, many studies suggest that eating unprocessed soy may improve hormonal function in women with PCOS!

Health Benefits of Soy for PCOS

Despite what you may hear on social media, research suggests that eating soy may be beneficial for women with PCOS. 

Improving Metabolic Health

Women with PCOS are more susceptible to metabolic disorders, like high blood pressure, heart disease, and type 2 diabetes. These conditions can further exacerbate your symptoms of PCOS.
Fortunately, studies looking at soy and PCOS found that soy intake reduces metabolic markers for these conditions. For example, soy intake may reduce both LDL cholesterol and triglyceride levels (7, 8, 9).
Insulin resistance is another hallmark feature of PCOS. Insulin is a hormone responsible for lowering your blood sugar levels after a meal. If you have insulin resistance, your cells do not properly respond to insulin signaling, which leads to high levels of both insulin and sugar in your bloodstream. Soy supplementation may reduce free insulin levels and improve the cells’ ability to properly respond to insulin (7, 8). This can make it easier to lose weight, normalize your cycle, and reduce common PCOS symptoms, like acne.

Soy May Lower Androgen Levels

High levels of androgens, like testosterone, are one marker of PCOS. High androgens worsen common PCOS symptoms like acne, facial hair, or hair loss.
Soy has shown to significantly reduce androgen levels in women with PCOS (7, 8, 9). This may be thanks to soy’s favorable effect on insulin levels, as reducing insulin can reduce androgens and associated symptoms.
Furthermore, soy may also beneficially increase the level of sex-hormone-binding globulin (SHBG) in your bloodstream (8). SHBG is a protein that binds tightly to hormones, like testosterone. By binding to testosterone, SHBG reduces the effects of free testosterone in women with PCOS, which then reduces unwanted symptoms, like acne and facial hair. 

Improving Fertility

Improving metabolic health, insulin sensitivity, and lowering high androgen levels can all improve ovulation and overall fertility.
One large study also found that increasing plant proteins, like edamame or tofu, in the diet significantly lowers the risk of infertility due to ovulatory disorders, like PCOS (10). Soy intake may also benefit women undergoing assisted reproductive therapy, like IVF, by improving implantation rates and live birth rates (11). 

Our Stance on Soy and PCOS

We use an individualized approach in helping women treat the root cause of their PCOS in our clinic. As such, we recognize that some people may not tolerate soy products (at first or at all). However, when considering the research and our clinical experience, we believe that many women with PCOS may tolerate, and even benefit, from including occasional whole food sources of soy into their diet. 

When including soy into your diet, keep these things in mind:
  • Choose whole food sources, like soybeans or edamame, to get the most benefit. Avoid processed versions like soy protein isolate or soybean oil.
  • Choose organically grown, non-GMO soy to significantly reduce glyphosate residue.
  • Avoid eating soy every day. We always encourage eating a diverse diet with many different types of foods! If you include soy into your diet, include no more than 2-3 servings per week.

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