Thyroid Boosters or Busters? The Truth About Thyroid Support Supplements

By Emory Hsu, MD

All-natural herbal thyroid support! Support your hormonal balance! Boost your energy level now with a healthier thyroid! You may have seen such statements online or at drugstore displays suggesting the power of supplements to enhance thyroid function. But do these products really have any effect on your thyroid gland and its function? And what miracle substance do they contain?

Like many things in the world, it’s wise to exercise caution in this matter — what sounds enticing or helpful may not necessarily be so. If you have an actual thyroid disorder such as hypothyroidism (low thyroid hormone level) or hyperthyroidism (too much thyroid hormone), then you should be monitored regularly by your endocrinologist and likely will need treatment with prescription medication. Conversely, if you don’t actually have a thyroid problem, there is no reason whatsoever to take thyroid hormone. Period. Even Consumer Reports recommends steering clear of all over-the-counter supplements marketed for thyroid support.

It’s vitally important to be aware of what these over-thecounter products contain. Some actually incorporate animal parts, including thyroid glands that have thyroid hormone in them. For example, if you see “bovine” (means cow) and/or “porcine” (means pig) in the ingredients list, the supplements usually have ground-up animal thyroids, which will provide varying amounts of thyroid hormone. This can potentially affect your body’s natural thyroid production and certainly will affect hormone levels.

It is also generally recommended to avoid dietary supplements containing bovine tissues because the cattle might have had bovine spongiform encephalopathy (BSE), more commonly known as mad cow disease, a fatal neurodegenerative disease that currently has no cure. Scientists say that those who directly ingest cattle tissue are at a lot more risk for BSE. In fact, the FDA issued warnings in 2000 and 2011 urging consumers to be extremely cautious and to avoid supplements that derive bovine from high-risk countries. Although mad cow disease is very rare in the United States, warnings like this are important to take to heart.

Some thyroid supplements claim to be all-herbal or natural. However, even those that supposedly contain no animal (and, thus, theoretically no thyroid) components have tested positive for thyroid hormone. A recent study showed that “adrenal support” supplements also can contain thyroid hormone – all 12 out of 12 tested brands contained detectable amounts of thyroid hormone and, if taken with label instructions, could lead to too much thyroid hormone in your body.

Also keep in mind that, unlike with prescription medication, there is no way of knowing how much thyroid hormone you will be taking in from a supplement, as the amounts of thyroid hormone may vary significantly even between different bottles of the same brand or manufacturer.

Additionally, many thyroid support pills claim to boost the thyroid gland’s interaction with iodine, a trace element that is essential for thyroid hormone production. However, boosting iodine function is oftentimes unnecessary. Although iodine deficiency is a major issue in other parts of the world, iodine nutrition status in the U.S. population has remained generally adequate for decades. There is little support for most individuals to consume iodine in the form of supplements as this actually could be harmful. Taking iodine supplements over an extended period of time can cause hypothyroidism by blocking thyroid hormone production. Plus, the risk of thyroid cancers such as thyroid papillary cancer or thyroid follicular cancer may also be higher in people taking iodine supplements. And thyrotoxicosis, a life-threatening complication resulting from elevated iodine levels, can also occur if you take iodine supplements. Symptoms include fever, confusion, rapid heartbeat and congestive heart failure. If you have any of these symptoms while taking iodine supplements, you need to seek immediate medical care.

Iodine can also be very irritative to the stomach. An overdose of iodine supplements can cause abdominal pain and, occasionally, bloody diarrhea. Corrosive gastritis (a group of conditions in which the stomach lining is inflamed), nausea, vomiting and bleeding from the intestinal tract has also been reported with high doses of iodine. For additional information about iodine excess, visit:

Adequate iodine intake – and, thus, proper thyroid function – can be achieved easily without taking supplements. As an example, one teaspoon of iodized table salt contains 400 micrograms of iodine, far more than the recommended daily allowance needed to keep thyroid hormone levels in an ideal range. However, keep in mind that not all salt is iodized, so it’s important to check packaging labels carefully for iodine levels. It’s also important to note that sodium (salt) used in processed and packaged foods has no iodine added to it and should not be counted towards one’s daily iodine intake. Iodine is present in many foods. Examples include cheese, cow’s milk, eggs, frozen yogurt, ice cream, saltwater fish, shellfish, soy milk and soy sauce. If you’re eating a lowsodium diet, iodine supplements are available to ensure adequate iodine consumption.

Also, there are foods known as goitrogenic foods that contain a chemical (isothiocyanate) that can affect your thyroid by blocking the enzyme that allows your thyroid to use iodine. Cruciferous vegetables all contain goitrogens, including all types of cabbages (regular cabbage, Napa cabbage, bok choy); Brussels sprouts; broccoli and broccoli rabe; cauliflower; kale; collard, mustard and turnip greens; radishes; and rutabaga. If you have normal thyroid function and your diet contains adequate amounts of iodine, these compounds will have no effect on your thyroid. However, to be safe, cooking these vegetables will ensure that they don’t affect your thyroid, as the goitrogenic compounds in the vegetables are destroyed by heat.

Other foods that contain goitrogens are soy, spinach, strawberries, peaches and peanuts. Fermenting soy disables the goitrogenic isoflavones found in soy foods.

It’s important to note that there is no one special diet or vitamin that has been proven to treat thyroid disease. And while some herbs and remedies may have beneficial effects for certain conditions, this doesn’t seem to be the case with the thyroid. Furthermore, supplements can make claims that are not proven or tested and are not approved by the Food and Drug Administration for treatment of any disease. While it may be fine to seek some forms of complementary and alternative care, be sure to talk to your endocrinologist first to determine if these remedies could safely be added to proven medical therapy.

And if you’re feeling tired or showing other signs of a faulty thyroid? In addition to the old-fashioned but time-tested techniques of getting adequate exercise, enough quality sleep and following a healthy diet, you can ask your primary care physician or endocrinologist to perform a thorough evaluation to screen for thyroid disease or other contributing factors such as depression or sleep apnea. That quick fix of a “thyroid support” pill is simply a fantasy.