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Medical Intel

Jan 31, 2019

People who are concerned about their thyroid health may turn to supplements. But thyroid supplements can cause the very problems they’re supposed to correct.



Intro: MedStar Washington Hospital Center presents Medical Intel where our healthcare team shares health and wellness insights and gives you the inside story on advances in medicine. In today’s episode, we talk to Dr. Kenneth Burman, Director of Endocrinology at MedStar Washington Hospital Center about thyroid supplements. The thyroid is a tiny organ that’s involved in regulating several major bodily functions including breathing, heart rate and body temperature. Over-the-counter thyroid supplements may seem like a good idea to someone who believes they may have a thyroid condition. But thyroid supplements actually can cause problems with the thyroid and we may not know exactly what’s in them.

Host: Dr. Burman, thanks for joining us.

Dr. Kenneth Burman: Sure. Thank you for the invitation.

Host: You bet. So, over-the-counter thyroid supplements—helpful or dangerous? Tell us about that topic.

Dr. Burman: Sure, be glad to. Over-the-counter supplements for the thyroid come into various categories. So, one type of supplement would be iodine or iodine containing substances. Another type would be substances that contain one type of thyroid hormone, or thyroid hormone analog. There are other ones that are much less well characterized, and we’ll focus on the iodine and the thyroid containing supplements. So, iodine is an interesting substance. It is required for the synthesis of thyroid hormone synthesis and also required for secretion of thyroid hormone. And, thyroid hormones, which are abbreviated T-4 and T-3, contain about 68 percent iodine. So normal iodine in a diet, minimum daily requirement is about 150 micrograms per day and some substances that we use in medicine such as IVP dyes or cat scans contain thousands of micrograms of iodine per day. Supplements can vary over-the-counter and are not necessarily regulated as to how much iodine they contain. So, if a supplement contains something close to the minimum daily requirement (about 150 micrograms) that should be fine and maybe even beneficial. But many of the supplements are not quantitated in terms of iodine, but also contain iodine that is very high in thousands of micrograms in a tablet. And if you take one a day, that would be thousands of micrograms a day.

So, what are the effects of iodine on the thyroid gland? They’re multiple. For a short period of time iodine in these concentrations will lower thyroid hormone secretion so we actually use supplements to very hyperthyroid people under very controlled circumstances. But that control of thyroid synthesis only occurs for 10-14 days approximately, and after that time, they escape from that effect and the iodine fuels worsening hyperthyroidism. Normal people may or may not have those reactions but those are possible, especially in the large percentage of patients in the population that have autoimmune thyroid disease and may not even know it. So, in summary, with regard to iodine, large amounts of iodine should be avoided by normal people and anyone with thyroid disease, a normal amount of iodine, a minimum daily requirement, is reasonable; and everyone, but especially people with a family history or known history of thyroid disease should avoid large amounts of iodine. With regard to thyroid hormone analogs, one of my former fellows and now colleague, Vick Burnett who is the head of endocrinology at Mayo Clinic, Jacksonville, did a nice study that he published of looking at supplements and measuring thyroid hormone in them. And it turned out, that of the 10 or 20 supplements that he looked at, almost all of them had a significant amount of thyroid hormone in them, even if they didn’t put that on the label. So, thyroid hormone itself, given to a normal person, can cause hyperthyroidism, which may be associated with a fast heart rate, palpitation, bone loss, and even more severe problems such as atrial fibrillation and should be avoided. And that these thyroid hormone analogs are difficult to identify in these supplements unless you specifically look for them. And it’s not just the standard hormones of T-4 and T-3 but there are various analogs of thyroid hormone that can cause similar problems that are not necessarily quantitated in these supplements.

Host: When we talk about over-the-counter supplements, are these people who self-diagnose themselves and then they just go out and they get the supplements?

Dr. Burman: Either because they are self-diagnosing themselves but perhaps, more commonly, they’re using it as health food or health additives to try to make them feel better or have more vigor. Of course, regular vitamins are key, and everyone should have adequate amounts of regular vitamins but iodine in excess, or thyroid hormone in excess, in any of these supplements should be avoided. And, of course, the FDA does not regulate supplements like they regulate medications.

Host: So, we don’t even know what’s in them necessarily.

Dr. Burman: Correct. So, this study by Dr. Burnett, it was unknown or unidentified exactly what the contents were and he was very surprised that it turned out to be significant amounts of thyroid hormone in many cases.

Host: So, for the most part, would you recommend people do not take them then or do consider them?

Dr. Burman: We would recommend that, in general, patients with any known thyroid disease not take supplements, and even normal individuals should ask their physicians to examine whether those particular supplements may contain thyroid hormone.

Host: What can happen if you take supplements and you don’t have a problem?

Dr. Burman: If you take supplements and you don’t have an endogenous thyroid problem, there could be enough thyroid hormone in them to cause overactive thyroid activity, just as if you had bona fide hypothyroidism. That can result in atrial fibrillation, heart irregularities, bone loss, and other significant problems.

Host: What other tips do we have on this topic? Anything else we need to share that people need to be aware of?

Dr. Burman: Yeah, it’s always of interest that people wonder where iodine comes from and in food, etc. in our normal American diet. So, I frequently ask the medical students “What’s the most common source of iodine in the American diet?” and they always, unanimously say, “salt.” But it turns out salt doesn’t contain that much iodine. That rather, it’s processed foods that contain iodine as a preservative—bread and pastries, to name one large source of iodine. And then another source of iodine that relates to health food is kelp. Kelp is seaweed which, of course, no matter how it’s prepared, has a large amount of iodine in it that can cause the problems of over or under activity.

Host: Great. Well, thank you for joining us on the show today and I appreciate everybody listening and hopefully you found this information helpful. Thanks again.

Dr. Burman: Thank you.

Conclusion: Thanks for listening to Medical Intel with MedStar Washington Hospital Center. Find more podcasts from our healthcare team by visiting or subscribing in iTunes or iHeartRadio.