Soy & Hashimoto's Thyroiditis

A doctor talks to her patient about interactions with her medications and eating soy.
Image Credit: KatarzynaBialasiewicz/iStock/Getty Images

The foods you eat can affect the health of many different organs in your body, including your thyroid gland. There are some concerns about the safety of soy products for people with thyroid diseases, including Hashimoto's thyroiditis. If you have this or any other thyroid disease, you do not need to eliminate soy foods from your diet, but you should talk to your doctor about how soy affects your treatment.

Hashimoto's Thyroiditis

Hashimoto's thyroiditis, also known as Hashimoto's disease, is a condition in which the immune system attacks the thyroid gland. The disease progresses slowly and may take months or years to be clinically detectable. This condition prevents the thyroid gland from making enough hormones. Symptoms of Hashimoto's thyroiditis include dry skin, fatigue, constipation, cold intolerance, hair loss, irregular periods, weight gain and the development of a goiter. It can usually be diagnosed by lab tests that measure thyroid hormone levels and detect the presence of antibodies that attack the thyroid gland.

Soy and Thyroid Function

If you consume soy products, you might be concerned that the soy is impairing the function of your thyroid gland. According to a 2006 article in "Thyroid," there are some concerns that consuming soy products can make your thyroid function less effectively. However, there is no evidence that consuming soy affects the health of your thyroid gland as long as it is working properly and you have adequate iodine intake. Thus, soy protein does not cause or exacerbate Hashimoto's thyroiditis.

Soy and Thyroid Hormone Absorption

If you have Hashimoto's thyroiditis, your doctor will probably prescribe synthetic thyroid supplements to treat the low levels of thyroid hormone in your body. Soy products can interfere with the absorption of synthetic thyroid hormone supplements. As a result, you may need to have a higher dose of these hormones if you regularly consume soy. Only your doctor should adjust your synthetic thyroid hormone dosage, so do not self-medicate by taking more synthetic hormone after consuming foods with soy.


If you are concerned that your thyroid is not functioning properly or that your dose of synthetic thyroid hormone is too low, talk to your doctor. If you are taking synthetic thyroid hormone to treat Hashimoto's thyroiditis, you do not need to completely eliminate soy from your diet. However, if you typically eat a high-soy diet, you should tell your doctor about this.