Is Soy Bad for Your Thyroid?

Eating soy foods can be beneficial for your health for many reasons. Aside from being incredibly versatile, soybeans contain fiber and omega-3 fats which can help reduce cholesterol and lower the risk of heart disease. Soy is also a complete protein, which means it has all nine essential amino acids that our bodies need. However, there is some skepticism regarding soy and its effect on the thyroid. The idea that soy can harm the thyroid is a belief held by some people due to misunderstandings. Read on to learn more about soy and your thyroid. 

Who Should Avoid Eating Soy?

Soy is generally safe to consume. The only people who should avoid soy completely are those who are allergic to it. However, soy is also known to alter thyroid function in people who are deficient in iodine. Iodine deficiencies occur if your body does not get enough iodine, which is a mineral your thyroid uses to make hormones. This leads to another condition that is commonly believed to interact with soy called hypothyroidism.


What Is Hypothyroidism?

Hypothyroidism, or underactive thyroid disease, happens when your thyroid cannot make enough thyroid hormones and release them into your body. Without enough thyroid hormones, your metabolism slows down and affects your entire body.

Common symptoms of hypothyroidism include:




Weight Gain




Cold Intolerance


Common Misconceptions About Thyroid Problems and Soy

As mentioned above, soy can affect those with hypothyroidism that is caused by iodine deficiency. However, iodine deficiencies are not very common in the U.S. because iron is included in many foods, most notably in table salt. Instead of avoiding soy altogether, people with iodine deficiencies are advised to increase their iodine intake.

Does Soy Interfere with Thyroid Medication?

Another common connection between soy foods and the thyroid is that soy foods can inhibit the absorption of thyroid medications that are taken by people with hypothyroidism. Although this may be true, soy foods may be singled out in this case but other foods in general can have this effect. For this reason, people who take medications for hypothyroidism are advised to take them on an empty stomach.

Can Soy Cause Thyroid Problems?

Soy foods do not cause problems in people who have normal-functioning thyroids and are not iodine deficient. Even people with thyroid problems can experience the benefits of soy. A study on hypothyroid patients showed that while a small percentage of them were affected by soy, all participants saw reduced blood pressure and found it easier to take their hormone insulin.


Now that you’ve learned more about soy and thyroid function, try one of our many flavorful soy recipes to find ideas for your next meal. You can also check out the Soy Myths and Facts page to learn about other common soy misconceptions.