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Woman holding various vitamins and supplements in one hand and glass of water in the other


The thyroid, a small gland located at the front of your neck, produces hormones that help control breathing, heart rate, digestion, and body temperature. When thyroid activity is low, a condition called hypothyroidism develops. Hypothyroidism can result from an autoimmune condition known as Hashimoto's disease, a disease in which the immune system attacks the thyroid gland and prevents it from making enough hormones. On the other hand, thyroid activity can be high — a condition known as hyperthyroidism. Hyperthyroidism can result from an autoimmune condition known as Grave's disease, a condition marked by overproduction of thyroid hormones.

In most cases, these thyroid conditions are treated with medications such as thyroid hormone replacement (e.g., levothyroxine) for hypothyroidism and antithyroid drugs (e.g., methimazole or propylthiouracil) or surgery for hyperthyroidism. However, since some evidence shows that certain dietary supplement ingredients may also help with thyroid conditions, supplement manufacturers have marketed products designed for "thyroid health."

Ingredients in "thyroid" supplements include iodine (sometimes incorrectly marketed as "nascent iodine"), selenium, zinc, acetyl-l-carnitine, ashwagandha, and guggul. While some of these supplement ingredients may be beneficial in certain people, in many cases, these supplements are not needed, and they may do more harm than good. Furthermore, some supplements marketed for "thyroid support" contained actual thyroid hormones, which can pose a risk if the hormone amounts are less or more than needed.

Sign in for more details about the potential benefits and possible safety concerns of ingredients and supplements for thyroid health (such as Thyroid Care Plus from Terry Naturally) and products made from the glands of animals (such as dessicated thyroid in Armour Thyroid), as well as information about ingredients such as alpha-lipoic acid, soy, resveratrol, quercetin, calcium, iron, and magnesium hydroxide, which may impair thyroid function or interact with prescription medication used to treat thyroid conditions, and whether eating cruciferous vegetables can impair thyroid function.

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September 25, 2021

A question about supplements that worsen thyroid function. A 2016 study cautions about prolonged silymarin intake, and it's effect on thyroid function.
Is there further guidance available on this topic?
October 2, 2021

Evidence that silymarin blocks the uptake of thyroid hormone by cells is based on only laboratory (in vitro) research. The interaction does not appear to have been confirmed in humans. However, if you are concerned about this interaction, the dose of milk thistle extract that can result in a blood level of the silymarin constituent (silychristin) that theoretically may affect thyroid hormone uptake appears to be 600 mg, so it may be prudent to stick to lower daily doses out of caution.

June 3, 2021

My doctor put me on Synthroid and nearly killed me. My thyroid does not convert t-3 into t-4. My daughter-in-law, a nurse practitioner, saw how I was acting, couldn’t remember anything, couldn’t think, tired all the time and suggested Armour. I change doctors, got on Armour, and now I’m a normal person again, The AACE should reevaluate their position.

April 11, 2021

I take armour because synthroid doesn't work for me. Insurance originally paid for it but the price quadrupled and insurance no longer pays for it.

April 25, 2021

I WAS on Synthroid but my hair fell out in heaps daily and I had balding on the sides of my head like men do but I'm female. Doctor put me on Armour Thyroid and the hair loss ended almost immediately. Shocked, elated, thrilled. Armour rocks my world:)

April 11, 2021

As a practicing physician assistant for 41 years who has been using dessicated thyroid hormone in many of my patients for many years, I have been pleasantly surprised to finally see an acknowledgment of this controversial use recently. The study finally confirms what I have seen through decades of medical practice; some patients respond much better to a mix of both T3 and T4, and we know there are receptors for both hormones throughout the body. Yes, T4 is the specific hormone most produced by thyroid gland, but T3 is the active hormone, produced through an enzymatic process which cleaves off one of the iodine molecules. Some patients may be deficient in this enzyme. Of course this statement requires scientific confirmation, but some patients, none the less, respond much better to this formulation.

December 9, 2014

I have recently begun to test serum iodine on my patients with thyroid disease or fatigue, and find it lower than the standard normal range on about 20% of patients. So, I don't know where the statement comes from that it is "vanishingly rare". If anything, it may be a little more common in people who avoid iodinized salt, preferring instead sea salt or Himalayan salt.

Also, checking a serum iodine may not be a "sensitive" way of finding iodine deficient patients. I think it is very "specific" though.

December 8, 2014

Seaweeds such as wakame, nori, and kombu contain substantial levels of bioavailable
iodine and may be used in various foods such as soups, curries, salads, etc.
Here is a report (one of many) from PubMed:

However, please be aware that kombu seaweed may have exceedingly high levels of iodine
when compared to wakame and nori, and should be used only in very small quantities.

December 7, 2014

Iodine deficiency, once common in North America, is now vanishingly rare here. The soil of northern Indiana and Ohio is low in iodine, and when people there ate mostly food grown there, they could be iodine deficient. Today, however, food is distributed widely -- Cleveland residents eat bread made with wheat from the great plains -- and the "goiter belts" have disappeared. Some scientists suspect we are now bringing on thyroid disease by excess iodine intake. Iodine deficiency is still common in some parts of the world, such as the Andes and parts of India, where all food is obtained locally.

September 6, 2015

Not so. Over the last 20 years food makers have stopped putting iodine in many salts and substituted bromine for iodine in baked goods. Iodine deficiency is now emerging again.

September 6, 2015

I mean substituted bromine for iodine. In fact, the Mediterranean salt I've bought clearly states 'this product does not contain iodide, a necessary nutrient." I can remember when all Morton salt was iodized. Not so today, must look for it.

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