Does Soy Slow Your Thyroid

Soy and your thyroid may not be a match made in heaven, and for some, it may seem to be more like a dive into hell. Especially, if that soy slows your thyroid to a crawl.

Eating large amounts of soy foods may not be good for some women’s thyroid functioning, according to new research from Loma Linda University in California.

However, another thyroid expert not involved in the study says the caution about not overdoing soy protein probably applies only to a minority of women and it should not cause concern for most.

In the new study, researchers tracked the diets of more than 800 men and women and then looked at their TSH (thyroid stimulating hormone) levels. Abnormally high TSH levels reflect a failing thyroid.

It may be that those with normal thyroid functioning will do OK eating soy foods, Dr. Tonstad says, “but in those who are borderline, it may take them above the threshold to give them hypothyroidism.” The thyroid gland is crucial to regulate metabolism and other bodily functions.

Of the 43 women with high TSH levels, she found, 13 had reported a diagnosis of hypothyroidism within three years of starting the study, but weren’t on thyroid pills now.

Overall, the men and women’s average TSH levels was 2.6 mIU/l (under 5 is ”normal”). Those with high TSH levels averaged nearly 8.

Here is where I disagree with this study. They are saying that a TSH reading under 5 is “normal”.  Many doctors who treat thyroid disease state that for patients to feel good, their TSH should be under 3 mIU/l. That tells me that most of the participants are still hypothyroid.

You can read about the study here:


Thyroid Gland: 12 Signs You May Be Facing Health Issues

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