Thyroid Supplements With a Kick

Posted 21 January 2014

Researchers who tested 10 popular thyroid-boosting products sold online found that nine contained the hormones thyroxine (T4) or triiodothyronine (T3), sometimes both. The amounts varied, but in some cases the recommended daily dose contained amounts of thyroid hormone as high or higher than delivered by prescription medications, according to the report, published in November in Thyroid, a scientific journal.


Thyroid Supplements With a Kick

By Roni Caryn Rabin

New York Times

Researchers who tested 10 popular thyroid-boosting products sold online found that nine contained the hormones thyroxine (T4) or triiodothyronine (T3), sometimes both. The amounts varied, but in some cases the recommended daily dose contained amounts of thyroid hormone as high or higher than delivered by prescription medications, according to the report, published in November in Thyroid, a scientific journal. 

At the recommended daily dose of four capsules, one supplement delivered 91 micrograms of T4 and 16.5 micrograms of T3, the researchers found. In clinical practice, the starting dose of T4 for patients with low thyroid function is just 25 micrograms a day; some older patients are given half that amount. A dose of 75 micrograms a day is sufficient to restore function in many petite women. 

“This supplement could give you as much thyroid hormone as you get in a prescription drug or more,” said Dr. Victor Bernet, chairman of endocrinology at the Mayo Clinic in Jacksonville, Fla., and senior author of the study. He became interested in so-called thyroid-support supplements after seeing a patient with inexplicable test results. The patient eventually admitted that he had been taking a supplement that a friend recommended for “low energy.” 

Thyroid disease is common — and more common in women, affecting one in 10 over age 50. Patients may suffer fatigue, lethargy and weight gain, but not everyone with those symptoms has the illness. Patients taking thyroid hormone should be checked regularly by a physician, Dr. Bernet said. 

“Thyroid hormone has a narrow therapeutic window,” he said, and “it’s easy to go over or under” the optimal dosages. 

Taking too much can disrupt the body’s ability to regulate hormone levels, and actually may trigger thyroid disease in a healthy person, Dr. Bernet said. Excessive doses of thyroid hormone also can cause anxiety, insomnia and emotional changes, as well as bone loss and serious heart problems. 

Officials with trade groups that represent supplement manufacturers said they were troubled by the study’s findings and would welcome regulatory enforcement against what one called the “few bad actors” producing adulterated products. 

“No dietary supplements should contain prescription drugs, period,” said John Shaw, chief executive officer of the Natural Products Association. “They are illegal and should be removed from the market,” he said, adding, “We don’t want dangerous products out there.” 

Both Mr. Shaw and Duffy MacKay, of the Council for Responsible Nutrition, another supplement trade association, suggested the tested products did not represent all of them, even though nine of 10 contained detectable levels of medication.

Mr. MacKay, a naturopathic doctor, said most consumers do not use “obscure” products like thyroid-support supplements. “This is a real fringe category, the outsiders of the outsiders of the outsiders,” he said. 

While the Food and Drug Administration can take action against unsafe supplements once they are on the market, the regulations governing supplements differ substantially from those for conventional medications, which go through extensive testing before approval. Under the Dietary Supplement Health and Education Act of 1994, supplement manufacturers are required to ensure that products are safe before putting them on the market. 

An F.D.A. spokeswoman said the agency has stepped up enforcement in recent years, in one case issuing warning letters about widespread violations of good manufacturing practices at an Atrium Inc. plant in Wautoma, Wis., that makes red yeast rice and other supplements. She declined to say whether the agency would be investigating thyroid-support products. 

Doctors are also concerned about iodine, an ingredient in about half the thyroid-boosting supplements. In order for the body to make thyroid hormone, it needs iodine, but excessive amounts of the element may be harmful, Dr. Bernet noted. 

The recent study did not analyze the iodine content in thyroid-support supplements, but labels on five of the products listed it as an ingredient, with amounts of 100 to 240 micrograms in the recommended daily dose. The recommended daily allowance for adults is 150 micrograms (slightly more for women who are pregnant or breast-feeding). A teaspoon of iodized salt contains 400 micrograms. 

For iodine, as for thyroid hormone, Dr. Bernet said, there is a “sweet spot” in the diet; too much or too little may be harmful. 

He and his co-authors did not make it easy for consumers who want to avoid supplements contaminated with thyroid hormone: The published paper did not identify the tested products. 

Dr. Bernet’s advice was to avoid all of these supplements. “You can’t trust any of these things. You don’t know what’s in them.” 


Thyroxine and Triiodothyronine Content in Commercially Available Thyroid Health Supplements 

Grace Y. Kang,1 Jonathan R. Parks,2 Bader Fileta,3 Audrey Chang,3 Maged M. Abdel-Rahim,3 Henry B. Burch,4 and Victor J. Bernet5 

Thyroid. October 2013, 23(10): 1233-1237. doi:10.1089/thy.2013.0101. 

Published in Volume: 23 Issue 10: September 25, 2013 Online Ahead of Print: September 14, 2013 Online Ahead of Editing: June 13, 2013 

1Department of Endocrinology, Landstuhl Regional Medical Center, Landstuhl, Germany.
2Department of Endocrinology, Tripler Army Medical Center, Honolulu, Hawaii.
3Department of Clinical Investigation, Walter Reed National Military Medical Center, Bethesda, Maryland.
4Endocrinology and Metabolism Division, Walter Reed National Military Medical Center, Bethesda, Maryland.
5Division of Endocrinology, Metabolism, and Nutrition, Mayo Clinic, Jacksonville, Florida. 

Address correspondence to: Grace Y. Kang, MD

Department of Endocrinology, Division of Medicine Landstuhl Regional Medical Center CMR 402, APO AE 09180 Landstuhl Germany E-mail: [email protected] 


Background: As defined by the Dietary Supplement Health and Education Act 1997, such substances as herbs and dietary supplements fall under general Food and Drug Administration supervision but have not been closely regulated to date. We examined the thyroid hormone content in readily available dietary health supplements marketed for “thyroid support.” 

Methods: Ten commercially available thyroid dietary supplements were purchased. Thyroid supplements were dissolved in 10 mL of acetonitrile and water with 0.1% trifloroacetic acid and analyzed using high-performance liquid chromatography for the presence of both thyroxine (T4) and triiodothyronine (T3) using levothyroxine and liothyronine as a positive controls and standards. 

Results: The amount of T4 and T3 was measured separately for each supplement sample. Nine out of 10 supplements revealed a detectable amount of T3 (1.3–25.4 μg/tablet) and 5 of 10 contained T4 (5.77–22.9 μg/tablet). Taken at the recommended dose, 5 supplements delivered T3 quantities of greater than 10 μg/day, and 4 delivered T4 quantities ranging from 8.57 to 91.6 μg/day. 

Conclusions: The majority of dietary thyroid supplements studied contained clinically relevant amounts of T4 and T3, some of which exceeded common treatment doses for hypothyroidism. These amounts of thyroid hormone, found in easily accessible dietary supplements, potentially expose patients to the risk of alterations in thyroid levels even to the point of developing iatrogenic thyrotoxicosis. The current study results emphasize the importance of patient and provider education regarding the use of dietary supplements and highlight the need for greater regulation of these products, which hold potential danger to public health.

4 comments to Thyroid Supplements With a Kick

  • Margi

    No No No I do not agree. I am on Euthyrox and without Thyroid support i.e Thyrostim c, I cannot function. Exhaustion, dry skin, dry eyes sluggish digestion, everything symptom which is reduced when I use the Thyroid support.

    My blood tests have been negative for years Suddenly my T3 was elevated and EVENTUALLY I was given Euthyrox. far far too late. An American Endocrinologist diagnosed Hashimotos Autoimmune and the South African Doctors deny that there is such a disease. It is all in my head.

    I do not trust anyone with my endocrine health except myself. I know how I feel and when I am well and when I am not.

    The thyroid support WITH Euthyrox is a miracle.

  • Hannali Krause

    Natural desiccated thyroid is much better than the wrong dose of T4 and I would rather be on it than on synthetic meds & be OPTIMAL ( all 5 my thyroid hormones). Screw TSH, being “normal” & docters that don’t listen. Docters should be re-educated. Lots of changes for thyroid treatment & they should start treatig their patients as individuals & stop keeping them hostage with an inadequate TSH bloodtest & so called outdated “normal” ranges. Also T3 is more important than T4. Many natural desiccated thyroid products are just labled as supplements to get them out there, but is actually hormone replacement therapy & has been successfully used since 1891.

  • Hannali Krause

    Oh, FYI, natural desiccated thyroid is not “alternative medicine” it was what wad used long before chemical meds. Chemical thyroid meds have only been developed in the 1970’s.

    • Harris

      “While desiccated thyroid contains both T4 and T3, the balance of T4 and T3 in animals is not the same as in humans, so the hormones in animal thyroid pills aren’t necessarily “natural” for the human body. Further, the amounts of both T4 and T3 can vary in every batch of desiccated thyroid, making it harder to keep blood levels right. Finally, even desiccated thyroid pills have chemicals (binders) in them to hold the pill together, so they are not completely “natural”. Desiccated animal thyroid is rarely prescribed today, and there is no evidence that desiccated thyroid has any advantage over synthetic T4 [1].” American Thyroid Association

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