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Updated: May 27


The thyroid is a small butterfly-shaped gland that is found in the front of the base of neck. It has the task of controlling many systems in the body. When this important gland goes haywire, side effects and symptoms like hair loss, weight gain, and severe mood swings can occur. To correct this, thyroid patients take thyroid hormone replacement, but taking this medication also means avoiding certain foods that can prevent the absorption of thyroid medication. One such food is soy, a species of legume that is fat-free but rich in protein.


To Avoid or Not to Avoid Soy, that’s the question!

There answer is Yes, and No! Who can and who cannot? There’s so much information out there regarding the thyroid and soy it almost seems as if we’re darned if we do or darned if we don’t. According to health expert Dr. Tonstad, patients with a normal functioning thyroid can consume soy but for those whose gland is failing, especially women, soy may take them above the threshold to hypothyroidism. This is because the isoflavones of soy can hamper the bodies to synthesize thyroid hormone.


Why Should Some Thyroid Patients Avoid Soy?

Soy naturally falls into the category of foods known as goitrogens, i.e. foods and supplements that prevent the production of thyroid hormone which can lead to an enlarged thyroid. Apart from reducing the absorption of thyroid medications, it may also inhibit the thyroid by reducing the actions of the hormones throughout the body.


Side effects of eating soy

As a matter of fact, Soy is a very good source of protein and it is found in food such as tofu, tempeh, miso, edamame beans, etc. Irrespective of its great benefits, experts believe that it affects the thyroid action in the system. Side effects include:



·       Decreased thyroid hormone

·       Hindering thyroid action

·       Malabsorption of certain minerals

·       Loss of libido

·       Higher risk of certain cancers, such as bladder and breast cancer



What kinds of soy should be avoided?

According to the publication by a medical journal “Thyroid”, natural soy foods like tofu and douchi are actually very healthy for all persons even those with thyroid conditions as long as they have enough iodine in their diet. The problem lies is in the consumption of isolated and genetically modified soy (GMO’s). According to Dr. Weil at Ask Dr. Weil “The issue of genetically modified soy is also controversial and a concern, as the corporations that are farming soy, claim that genetically modified organisms (GMO) in foods, including soy, are safe, while experts on the holistic side of healing say otherwise (me included).” In fact, research shows that GMO’s are said to be endocrine disruptors, so it’s would seem it’s a double whammy when consuming GMO soy.

It’s important to note that 90% of all Soy beans are genetically modified, so look for organic sources when possible. 


List of soy foods to avoid

For those who have thyroid problems the chance of having a high TSH is and since the excessive consumption of soy can lead to it, these are some soy foods to avoid:


·       Edamame

·       Miso

·       Soy nuts and milk

·       Tempeh

·       Tauco

·       Textured soy protein: a product made from textured soy flour

·       Kinako: roasted soybean flour


Soy Alternative

Soy is a rich source of protein cannot be avoided outrightly without any replacement. To complicate matters, soy has been proven to lower the risk of heart diseases, cholesterol and fat level making it an important food source. With this in mind, experts have suggested that soy should be taken cautiously for those who are at risk of thyroid disease or who have the disease already. Another great alternative to soy or soy sauce is coconut amino’s which can replace and serve perfectly well the purpose of soy for all thyroid patients and it’s delicious! Coconut Amino are sold in stores like Trader Joe’s, Whole Food and Fresh Market and are very reasonably priced.



In 2006, the medical journal, “Thyroid”, published findings that revealed that soy foods, in the form of real foods, like tofu and tempeh and not the processed versions of soy, like isolated soy proteins were, in fact healthy for people, including some with thyroid conditions if they had enough iodine in their diets the soy was consumed several hours after their thyroid medication was taken.

So, if you can’t avoid soy foods, try to limit your intake and also consume foods or take a good multivitamin that also contains iodine. Studies have shown that there is a relationship between excessive consumption of soy and thyroid diseases, and therefore, thyroid patients should limit their intake or take other alternatives like coconut amino. According to Dr. Weil we should limit our consumption to 20-30 mg of isoflavones per day if consuming the proper daily amount of iodine. But, on average Americans consume more than 80 mg per day due to processed foods like protein bars, soy milk, soy nuts or cereals enriched with soy and soy supplements.


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