Recently, there has been much talk about soy and how it affects the thyroid gland. Some people say that eating soy is harmful to the thyroid and can cause hypothyroidism. First, we need to understand what the thyroid is and what the difference is between hyperthyroidism and hypothyroidism.
Your thyroid is really a gland in your neck and it produces hormones that help to regulate your body’s metabolism, as well as the amount of Calcium in your blood.
Hyperthyroidism is when the thyroid gland is overactive and produces too much thyroid hormone. The most common cause of hyperthyroidism is autoimmune; it’s when the body’s immune system attacks its own thyroid gland tissue, causing it to produce large amounts of hormone. This is most common in women between age 20-40 years. One of the most noticeable physical signs is a goiter, or an enlarged thyroid. Some of the other physical signs of hyperthyroidism include tremors, moist skin, and patchy hair loss.
If the thyroid gland is underactive and not enough hormones are produced, we are diagnosed with hypothyroidism. The most common cause of hypothyroidism is iodine deficiency. Hypothyroidism can also occur if the thyroid gland is damaged and not able to make enough of the hormone. This is called Hashimoto’s Thyroiditis. Some of the physical signs of hypothyroidism are: increased tiredness, muscle weakness, loss of body hair, especially the eyebrows, weight gain and depression.
Now that we have our definitions of Thyroiditis, or Thyroid Disease, let’s talk about hypothyroidism and why some people say that eating soy can cause hypothyroidism.
What these people may be talking about is this: If you already have hypothyroidism and you are taking a thyroid hormone medication as a treatment, then eating soy can interfere with the absorption of thyroid medication. Most doctors recommend taking thyroid medication on an empty stomach and to wait one hour before eating. And this advice is given because there are many foods and supplements that can interfere with the thyroid medication. Other foods/supplements that can impair the absorption of thyroid medication are: calcium, iron, and cholesterol drugs. Many doctors will advise patients to take the medication before eating anything to avoid any interference with the thyroid medication.
There is no evidence out there to suggest that soy can directly cause thyroid disease, or that soy directly affects the thyroid in any way. On the other hand, in the Journal, Nutrients 2013, (5(11):4642-4652); Tonstad S, Nathan E, Oda K, Fraser G. Vegan Diets and Hypothyroidism), research was done to show that a “Vegan diet tended to be associated with lower, not higher risk of hypothyroid disease.”
Since the most common cause of hypothyroidism is iodine deficiency, an iodine-rich diet, like sea-vegetables, i.e. seaweed such as kelp, nori, wakame and arame are perfect. They are all rich in iodine, protein, calcium, Vitamin A, some B Vitamins, and lignans. Lignans are known protect against cancer. Sea-vegetables are often used to treat a goiter. In Okinawa, Japan, the life expectancy is the longest in the world. This is mostly due to a diet rich in seaweed.
Once again, research shows that a vegan diet is beneficial in more ways than one. Cheers to all the Vegans out there!