Some people think soy is a great plant-based protein option, but what are the dangers of eating soy? Learn about the risks and benefits, plus some ways to consume soy safely.

soy beans and soy milk

With the rise in popularity of vegetarian and vegan diets, soy has stepped onto the scene as a source of plant-based protein. Those who don’t eat meat praise the protein content of soy.

One cup of boiled soybeans contains about 29 grams of protein which is comparable to the protein found in a serving of meat. Soy also contains vitamins and minerals such as copper and phosphorus.

There are some health concerns around soy consumption, though. The Paleo diet movement in particular, has helped highlight the potential dangers of eating soy, ranging from the phytoestrogens present in soy to the high levels of antinutrients in soy.

Where is soy in food?

In the United States, soy is most commonly consumed as a replacement for animal products, as an emulsifier in processed foods, or in soy sauce. You’ll also find soy in these common products:

  • Soy-based infant formula, as a replacement for breast milk or milk-based formula
  • Chocolate bars, processed foods, and some supplements as soy lecithin used to preserve shelf life and improve texture
  • Tempeh and tofu, as a replacement for meat
  • Soy milk, as a replacement for dairy milk
  • Condiments such as soy sauce or miso paste used to add flavor to traditional Asian dishes
  • Natto and edamame, as snacks or side dishes
  • Soy protein isolate, as plant-based protein powder, either used alone as a powder supplement or used in protein bars/bites/etc.
  • Processed and conventional meat: even though soy is used as a meat alternative, it has also been used as a filler in processed meat and the diets of conventionally-raised animals are often supplemented with GMO soy feed.
tofu veggie bowl

Dangers of Eating Soy

Soy is controversial for a few different reasons, the most common being the isoflavones present in soy (see below for more information). Soy is also one of the top 8 allergens in the United States–such a highly allergenic food invites controversy, whether founded or not, unto itself.

Other controversial characteristics of soy include GMOs, antinutrients, and goitrogens. Here is some more in-depth information about each controversial characteristic of soy.

1. Isoflavones (phytoestrogens)

Isoflavones, also known as phytoestrogens, are particularly concentrated in soy. These natural compounds have a chemical structure similar to the human hormone known as estrogen; thus, they can attach to estrogen receptor sites in the human body and affect natural estrogen production and metabolism.

The possible manipulation of estrogen as a result of eating soy or soy products is a big potential danger of eating soy. The harmful effects may be exacerbated with non-organic, highly processed forms of soy.

Having excess estrogen in the body can have an array of health consequences. These include, but are not limited to: breast cancer (though some research indicates a lower risk of breast cancer in women who consume soy), estrogen dominance, acne due to imbalanced hormones, endometriosis, male infertility (though more research is needed), and–in rare cases–gynecomastia (male breast growth).

2. GMOs

As much as 80% of soybean production in the United States comes from genetically modified soybeans. GMOs were only introduced to the public food supply in 1994 and there has been no opportunity to conduct long-lasting studies of the effects of GMO-containing diets.

3. Antinutrients

Soy, like other legumes, is high in phytic acid. Phytic acid is an antinutrient, meaning it is the plant’s natural protective system that impedes the absorption of nutrients when consumed.

If you’re eating soy for the high levels of nutrients, some of them are bound to antinutrients and are therefore unavailable to your body. Antinutrients can even bind to other minerals and vitamins present in your body, leaching them from you.

Soy also contains protease inhibitors, which inhibit the metabolism of certain types of proteins.

4. Goitrogens

Soy contains naturally higher levels of goitrogens, which can interfere with proper thyroid function when consumed in excess.

Benefits of Eating Soy

Some health experts encourage the consumption of soy for its health benefits. Like most foods, there are both downsides and upsides to consuming soy. Keep in mind that when consuming soy, you’ll get the most nutrient density from organic, non-GMO soy in its whole form.

And, or course, please do consult your healthcare provider to help determine whether soy is safe for you.

Here are some commonly perceived benefits of eating soy and the associated research.

tofu veggie soup bowl

1. Possible Lower Risk of Breast Cancer

Some research has shown that females who consume soy prior to and during pre-adolescent breast development have a lower risk for breast cancer later in life.

2. Lower LDL (“bad” cholesterol)

Though soy has been touted as beneficial for lowering high levels of Low-density lipoprotein (LDL), the amount is indirect and not significant. The FDA has revoked the claim that soy is beneficial for lowering LDL levels.

3. High in nutrients

Soy is particularly high in iron, calcium, potassium, phosphorus, and copper.

4. Lowers blood pressure

There is data to suggest that soy is hypotensive, meaning it helps lower blood pressure, and therefore can reduce the risk of cardiovascular disease.

Safer soy consumption

If you choose to incorporate soy into your diet, it’s best to be sure you’re consuming it in moderation and that you’re getting high quality, properly prepared soy.

Ideally, the soy you consume should be:

  • Organic: at least 80% of soy in the United States is genetically modified, but you can avoid both GMOs and heavy pesticide use by choosing certified organic soy
  • Soaked/sprouted: like all legumes and beans, the digestibility of soy can be improved through soaking and/or sprouting. This traditional method of preparation lowers antinutrients and makes it easier to digest (though a significant amount of the antinutrients still remain.)
  • Fermented: fermented soy products like tempeh and natto offer an impressive nutrient profile, probiotics, and increased digestibility.
  • Whole: avoid soy protein isolates, which contain all of the isoflavones and antinutrients with none of the vitamins and minerals. Soy protein isolate is notoriously difficult to digest.
human being in wood with gray background


Is soy really bad for you?

Soy has a variety of benefits and risks. Its macronutrient profile is more desirable than other beans or legumes as it is higher in protein and fats and lower in carbohydrates. Soy also contains a relatively high level of vitamins and minerals.
On the other hand, soy’s isoflavones and antinutrients may have detrimental effects on hormones, digestion, and nutrient absorption.

What are the negative effects of soy and what impact can it have on the female body?

Some believe the negative impacts of soy outweigh the potential benefits. Soy is particularly high in isoflavones–these naturally occurring phytoestrogens can mimic estrogen in the body, attaching to estrogen receptor sites and contributing to excess levels of estrogen in the body.

We’re already exposed to higher levels of estrogen than ever before due to xenoestrogens, which are environmental estrogens found in plastic, personal care products, and medications such as birth control. High xenoestrogen exposure, poor diet, and lifestyle (which inhibits proper estrogen metabolism and overall hormonal balance), and excess consumption of phytoestrogens can all contribute to estrogen dominance in women.

Considering that estrogen dominance is a relatively new phenomenon, coming about with the advent of hormonal birth control, increased plastic use, and worsening diets/stress levels, we cannot say for certain that estrogen dominance does not contribute to poor health later in life, or even shortened life spans.

While we cannot control all of the xenoestrogens we’re exposed to as they’re simply too prevalent now, we can control our diets. Choosing to avoid phytoestrogenic foods such as soy may help reduce your risk of estrogen dominance.


There are some potential dangers of eating soy, especially processed forms. However, if you still wish to include soy in your diet, consume properly prepared, high-quality soy in moderation. Speak with your healthcare provider if you have questions about whether or not unprocessed soy products are appropriate for you.

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Note: this post is for informational purposes only and is not intended as medical advice. Please consult your healthcare provider for recommendations related to your individual situation.