Patients who take over-the-counter supplements that promise to enhance thyroid function may not be sae
Supplements MAY Use Cow Thyroid
Grace Kang, MD, chief of endocrinology at Landstuhl Regional Medical Center in Germany, and colleagues decided to look into 10 popular thyroid supplements after one of their co-authors saw a patient who developed thyrotoxicosis after taking over-the-counter thyroid supplements.
In a study in Thyroid, they analyzed the biochemical composition of these supplements via liquid chromatography to measure levels of the two main thyroid hormones — thyroxine (T4) and triiodothyronine (T3).
They found that nine of the 10 supplements had detectable levels of either thyroid hormone, and when taken at recommended daily doses, make patient thyrotoxic.
Even when patients do have clinically diagnosed hypothyroidism, giving the exact needed dose of thyroid hormone is critical, because thyroid drugs are classified by the FDA as having a narrow therapeutic index.
And it’s not just excess thyroid hormone that poses a problem for thyroid supplements, Some are formulated with high doses of iodine, the main element used by the thyroid to synthesize its hormones.
Often these supplements are made from seaweed, she said, and can contain as much as 800 mcg of iodine per drop, when the standard recommended daily intake is only 150 mcg.
They can also be contaminated with heavy metals, particularly arsenic. Seaweed is exposed to these compounds in seawater and when it’s dried out, the arsenic and other contaminants can concentrate.
Thyroxine and triiodothhyronine content in commercially available thyroid health supplements
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.
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.
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.
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.