Can dietary supplements boost my thyroid function?

By Jeffrey I. Mechanick, MD, FACP, FACE, FACN, ECNU

Low thyroid function should be considered when someone complains of typical symptoms, such as fatigue, weight gain, constipation, and dry skin. But as you can imagine, these symptoms could also be due to many other causes. So a diagnosis of low thyroid function must always be made by your doctor and generally requires a “TSH” test (See link). The standard treatment for low thyroid function is levothyroxine [le-vo-thigh-ROX-een], a synthetic medicine that is basically the same as the thyroid hormone that your own thyroid gland produces.

From time to time, you may get advice about other ways to treat low thyroid function or hypothyroidism [hie-po-THIGH-roid-is-m]. The source could be the internet, a friend, or even a doctor or nurse. Besides making sure that you actually have low thyroid function, properly diagnosed by your doctor, you should be aware of some important points about the use of dietary supplements that are marketed or claimed to have thyroid-related actions. Bear in mind as you read this that there are no scientific studies showing that dietary supplements actually improve thyroid function in any significant and safe manner. As more research is done, some dietary supplements may show promise, but levothyroxine is still the proven, safe way to treat low thyroid function.

There are three broad types of dietary supplements that you may encounter regarding your thyroid.

Supplements that contain a lot of iodine

Kelp, a type of seaweed, contains a lot of iodine. Kelp may be suggested as a logical and natural way to boost the function of your thyroid. After all, thyroid hormone contains iodine so increasing the amount of iodine in your diet should be good for your thyroid, right? Unfortunately, this is not the case. In fact, a high level of iodine intake may reduce the amount of thyroid hormone secreted or released from your own thyroid gland.

Substances that are claimed to promote thyroid function

B-complex vitamins, garlic, ginger, gingko, licorice, L-tyrosine, magnesium, manganese, meadowsweet, oats, pineapple, potassium, saw palmetto, selenium, tiratricol (TRIAC), and valerian have all been claimed to improve thyroid function. The theory behind many of these claims is attractive and very interesting. However, there is not enough data to support using these substances instead of levothyroxine for the treatment of hypothyroidism or an underactive thyroid.

Animal-derived thyroid extracts or desiccated [DESS-ih-KATE-ed ] thyroid

Desiccated thyroid has been used to treat hypothyroidism for many years, but is rarely taken anymore. Most people switched to levothyroxine by the end of the 1970s. People may also seek out thyroid extract as a treatment for low thyroid function because they prefer “natural” treatments. Though this type of treatment still works by replacing the missing thyroid hormone from the body, it does not provide levels that are either as consistent or easy to monitor as levothyroxine does. In fact, if you search the internet for controlled clinical trials involving low thyroid hormone treatment, you will find a lot of strong evidence for levothyroxine and virtually none for thyroid extract.

So, when it comes to the treatment of any medical condition and specifically an underactive thyroid, the safest and most effective treatments should be used. Remember these key points:

• If you suspect that you have low thyroid function, see your doctor.
• If you truly have low thyroid function, levothyroxine should be used.
• At the present time, there is no proven role for the use of dietary supplements to boost thyroid function.
• If there is any doubt or question about an accurate diagnosis or best treatment for low thyroid function, consult an endocrinologist [en-doh-cri-NA-lo-jist].

Dr. Mechanick is Clinical Professor of Medicine and Director of Metabolic Support in the Division of Endocrinology, Diabetes, and Bone Disease at Mount Sinai School of Medicine in New York City. He has authored over 170 publications in endocrinology and nutrition and edited/authored five books in the fields of diabetes, nutrition, thyroid, and metabolic bone disease. Dr. Mechanick is in private practice in endocrinology and metabolic/nutrition support in New York. He currently serves as Vice President and Treasurer of the American Association of Clinical Endocrinologists (AACE).