Is Soy Bad For Your Thyroid?

When people try to eat better, the first word of advice tends to be eliminating either saturated fats or sugars. And there is good reason for this: Excessive saturated fat consumption, particularly in the form of highly processed meats, has been linked to heart disease, and sugar is known to wreak havoc on the body’s blood sugar levels and insulin response.

However, there’s one sneaky ingredient you may not have thought to give up: soy. While unrefined soybeans in their purest form may have some demonstrable health benefits, the huge majority of soy that you’ll find here in the U.S. is potentially harmful to your health—especially your thyroid.

Soy and Processed Foods

First, let’s get one thing out of the way: Pick up a processed food product, and it’s almost guaranteed to contain soy, whether in the form of soybeans, soybean oil, soy protein isolate or soy lecithin. The U.S., Brazil, Argentina, China and India are the main producers of soy, and within the United States, much of that production goes toward processed foods, according to Very Well.

Actress Blake Lively told People magazine that, in order to lose her baby weight after giving birth to daughter, she gave up soy. 

“Once you remove soy, you realize you’re eating no processed foods,” she said. “So that’s basically what I did. No processed foods and then working out.”

The Effect of Soy on Your Thyroid

However, it isn’t just processed foods containing soy that could be bad for your health. Even so-called heath foods like tofu could do some damage to your body.

Holistic Nutritionist, CPT, CES and author of the wellness blog Fit Women for Life, Nick Garcia explains some of the dangers of soy:

“Soy contains goitrogens, which are substances that block the synthesis of thyroid hormones and interfere with iodine metabolism, thereby interfering with your thyroid function,” he explains.

Synthetic estrogens are linked to a great number of health problems in modern society. Plastics, for example, are a deeply feared source of xenoestrogens. These synthetic estrogens mimic estrogen in the body, and have been suspected to lead not only to decreased thyroid function, but also hormonal imbalance and certain cancers.

Other Harmful Effects of Processed Soy

The suspected dangers of soy don’t end there.

“Soy contains phytates (phytic acid), which bind to metal ions, preventing the absorption of certain minerals, including calcium, magnesium, iron, and zinc — all of which are co-factors for optimal biochemistry in your body,” says Garcia. “This is particularly problematic for vegetarians, because eating meat reduces the mineral-blocking effects of these phytates (so it is helpful—if you do eat soy—to also eat meat).”

So, Should You Give Up Soy?

It’s not quite as simple as stating that everyone should give up soy. After all, Chinese populations have been eating tofu for more than 5,000 years, using it as both a medicinal solution and a food source.

According to Very Well, many nutritionists suspect that it’s modern civilizations’ overconsumption of soy that’s to blame for much of these issues. After all, when people eat processed foods regularly, they’re going to get huge quantities of soy in their systems.

“(Some experts) argue that soy that is not genetically modified, and consumed in food forms — like tofu, tempeh and miso — can be safely incorporated into the diet when used in moderation…as a condiment, and not as a primary protein source,” says Very Well.

So, consider using non-GMO soy sauce or snacking on edamame, but perhaps not using tofu as a daily substitute for meat.