Four of those that tested positive listed the ingredient "bovine thyroid tissue," which might naturally contain hormones. But five supplements that tested positive listed only herbal ingredients, such as ashwagandha, guggul, and Coleus forskohlii.

That is concerning because healthy thyroid hormone levels are very precise and taking supplements that contain these hormones can alter those levels in unpredictable ways. It's also impossible to know how much thyroid hormone a supplement might contain.

Several of the supplement samples the researchers tested contained doses of thyroid hormone that were higher than 25 mcg—the lowest dose of levothyroxine available by prescription. And one contained more than 90 mcg—slightly less than a doctor would prescribe for a patient whose thyroid gland had been removed.

We need only mcg of iodine per day in our diet, according to the Institute of Medicine. But ingesting excess iodine can cause health problems. It is particularly worrisome for people with thyroid nodules—bumps on the thyroid glands that can be very small and often go unnoticed.

Conversely, studies also show that too much iodine more than around mcg per day can cause the thyroid to slow down or even stop producing hormones in certain people—the opposite effect of what many people hope these supplements will do for them.

That can result in weight gain and fatigue, and can increase your risk of cardiovascular disease ," Lipman says. Yet many supplements contain more than mcg of iodine. For example, both Enzymatic Therapy's Metabolic Advantage and Whole Foods' Thyroid Complete contain mcg per two-capsule serving.

Follow the recommendation on the labels and swallow two capsules three times a day and you've ingested mcg of iodine—enough to cause health problems in certain people if taken long term. Kelp, a type of seaweed that is often marketed for thyroid health, is loaded with iodine.

For example, a serving one drop of Liquid Kelp, a dietary supplement promoted for "Thyroid Gland Support," contains mcg of iodine. But if you take a supplement that contains kelp, plus a multivitamin, such as GNC Women's Ultra Mega One Daily containing mcg of iodine, and also use iodized salt that contains mcg of iodine per teaspoon, it's easy to consume far more iodine than your thyroid needs—or that is healthy.

Glandular organs such as thyroid, liver, pancreas, heart, and spleen, can be found on the ingredients list of some thyroid and metabolic support supplements. For example, Natural Sources' Raw Thyroid supplements contain raw thyroid, adrenal, pituitary and spleen bovine tissue.

But our experts say that ingesting ingredients like these is not wise. The disease has been linked to eating material from cows infected with mad cow disease ," Hansen says. Prions, the agents that spread mad cow and Creutzfeldt—Jakob disease, are most commonly found in the brains of cows, but there is evidence that if an animal has an infection, you can also find prions in their spleens, kidneys, and other glandular organs," Hansen says.

Thyroid problems can be diagnosed easily through blood tests, but taking supplements that can alter the level of thyroid hormones in your blood can mask thyroid issues. And because supplements aren't regulated the same way drugs are, they can contain varying amounts of active ingredients.

The Council for Responsible Nutrition, a trade association that represents the dietary supplement industry, acknowledges that thyroid supplements can interact with prescription medications.

And, says Duffy MacKay, N. Yet Stephanie Lee, M. Bottom line: Do not take thyroid supplements. If you suspect that you have a thyroid condition, head to your doctor's office instead of the vitamin or natural-foods store. Getting the right diagnosis and treatment is the key to combating weight gain, exhaustion , and brain fog.

I cover health and food at Consumer Reports, helping consumers to make smarter choices, whether they're shopping for shrimp or searching for a top-notch doctor. van Zuuren, E. Selenium supplementation for Hashimoto's thyroiditis: summary of a Cochrane systematic review. European thyroid journal , 3 1 , 25— Santos, L.

Selenium and Selenoproteins in immune mediated thyroid disorders. Diagnostics Basel, Switzerland , 8 4 , Ventura, M. Selenium and thyroid disease: from pathophysiology to treatment.

International journal of endocrinology , , National Institutes of Health Office of Dietary Supplements. Zinc deficiency associated with hypothyroidism: an overlooked cause of severe alopecia.

International journal of trichology , 5 1 , 40— Rabbani, E. Randomized study of the effects of zinc, vitamin A, and magnesium co-supplementation on thyroid function, oxidative stress, and hs-CRP in patients with hypothyroidism. Biological trace element research , 11 , — Foster, M. Effect of vegetarian diets on zinc status: a systematic review and meta-analysis of studies in humans.

Journal of the science of food and agriculture, 93 10 , — Katagiri, R. Effect of excess iodine intake on thyroid diseases in different populations: A systematic review and meta-analyses including observational studies. PloS one , 12 3 , e Chung H.

Iodine and thyroid function. Maldonado-Araque, C. Iron deficiency is associated with Hypothyroxinemia and Hypotriiodothyroninemia in the Spanish general adult population: Di bet.

es study. Scientific reports , 8 1 , Luo, J. Iron deficiency, a risk factor of thyroid disorders in reproductive-age and pregnant women: a systematic review and meta-analysis. Frontiers in endocrinology , 12 , Name, J.

Iron bisglycinate chelate and polymaltose iron for the treatment of iron deficiency anemia: a pilot randomized trial. Current pediatric reviews , 14 4 , — Milman, N. Ferrous bisglycinate 25 mg iron is as effective as ferrous sulfate 50 mg iron in the prophylaxis of iron deficiency and anemia during pregnancy in a randomized trial.

Journal of perinatal medicine , 42 2 , — Published March 10, Aon, M. Vitamin B12 cobalamin deficiency in overt and subclinical primary hypothyroidism. Clinical medicine insights. Endocrinology and diabetes , 15 , Aktaş H. Vitamin B12 and vitamin D levels in patients with autoimmune hypothyroidism and their correlation with anti-thyroid peroxidase antibodies.

Medical principles and practice : international journal of the Kuwait University, Health Science Centre , 29 4 , — Benvenga, S. The role of inositol in thyroid physiology and in subclinical hypothyroidism Mmnagement. National Institutes of Health Office of DIetary Supplements.

Vitamin C. Ardabilygazir, A. E ffect of High-dose Biotin on Thyroid Function Tests: Case Report and Literature Review.

Cureus , 10 6 , e Use limited data to select advertising. Create profiles for personalised advertising. Use profiles to select personalised advertising.

Create profiles to personalise content. Use profiles to select personalised content. Measure advertising performance. Measure content performance. Understand audiences through statistics or combinations of data from different sources. Develop and improve services.

Use limited data to select content. List of Partners vendors. By Sarah Anzlovar, MS, RD. Medically reviewed by Danielle Weiss, MD.

Fact checked by Rich Scherr. Editor's Note Our team of registered dietitians reviews and evaluates every single supplement we recommend according to our dietary supplement methodology. Our Top Picks. Best Vitamin D:. Best Selenium:. Best Zinc:. Best Iodine:. Best Iron:.

In This Article Expand. Our Picks. Are Thyroid Supplements Beneficial? Who May Not Benefit from Thyroid Supplements. We Do Not Currently Recommend. How We Select Supplements. What to Look For. Best Vitamin D. Nature Made Vitamin D3. Pros USP Verified Budget-friendly Research-backed maintenance dose.

Cons Not suitable for soy-free or vegan diets. Best Selenium. Now Foods Selenium mcg. Pros Third-party tested and extensive in-house testing Budget-friendly Allergy-friendly, vegan, Non-GMO. Cons Dose may be higher than some needs. Best Zinc.

Thorne Research Zinc Picolinate. Pros NSF Certified for Sport Third-party tested Zinc is the only ingredient. The 7 Best Zinc Supplements of Best Iodine. Swanson Kelp. Pros Third-party tested Budget-friendly. Cons May not be appropriate for someone with shellfish allergy.

Important Note About Iodine Supplementation Excess iodine is problematic for thyroid health and can exacerbate hypothyroid. Best Iron. Pros Third-party tested Vegan, Non-GMO, and gluten-free Form is gentler on gastrointestinal system.

Cons Some may not like the taste. The 9 Best Iron Supplements of The following groups of people may not benefit from supplements: Those that have had their thyroid removed.

People with adequate nutrient levels. The benefits of vitamin and mineral supplements to support thyroid health are tied to nutrient deficiencies. In some cases, over supplementation can actually be problematic.

Thyroid Supplements We Do Not Currently Recommend Combination thyroid supplements: There are many supplements marketed to support thyroid health that combine a variety of vitamins and minerals and sometimes herbs and other ingredients.

How We Select Supplements Our team works hard to be transparent about why we recommend certain supplements; you can read more about our dietary supplement methodology here. We interviewed the following experts to get thyroid supplement recommendations: Jillian Greaves, MPH, RD, LDN Melissa Groves Azzaro, RDN, LD What to Look For Third-Party Testing Supplements that are third-party tested are sent to a lab where they are tested to ensure they contain what they say they contain and are not contaminated with specific high-risk, common contaminants.

Not all third-party testing is created equal. It is not uncommon for supplement companies to pay labs for certificates after conducting minimal to no testing. The third party certifications we can trust are: ConsumerLab. com , NSF, and USP. Sometimes products tested by these three companies are more expensive to try to offset the cost they pay for certification.

We recommend doing some research on the reputability of the manufacturer, and calling up the manufacturer and their testing lab to determine their protocols and decide if you feel comfortable consuming the supplement. Form Most vitamin and mineral supplements come in a variety of forms.

Thyroid Supplement Dosage Always speak with a healthcare professional before adding a supplement to your routine to ensure that the supplement is appropriate for your individual needs and to understand which dosage to take. How Much is Too Much? Whether individual supplement or a combination product like a multivitamin, you can ensure that your supplement does not exceed those upper limits by running your supplement by a healthcare provider Frequently Asked Questions What supplements should not be taken with thyroid medication?

Can I take collagen supplements with thyroid medication? What supplements affect thyroid tests? Are thyroid supplements safe? What other ways can I boost my thyroid naturally? The 6 Best Fiber Supplements of , According to a Dietitian.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Nevertheless, people who are desperate to lose weight and feel more energetic turn to supplements that are marketed to boost metabolism and energy "naturally. Here's why:. It isn't possible to know if a supplement contains thyroid hormones from reading the label, but a study published in the journal Thyroid found that nine out of 10 supplements marketed for thyroid health and support contained real hormones.

Four of those that tested positive listed the ingredient "bovine thyroid tissue," which might naturally contain hormones. But five supplements that tested positive listed only herbal ingredients, such as ashwagandha, guggul, and Coleus forskohlii.

That is concerning because healthy thyroid hormone levels are very precise and taking supplements that contain these hormones can alter those levels in unpredictable ways. It's also impossible to know how much thyroid hormone a supplement might contain.

Several of the supplement samples the researchers tested contained doses of thyroid hormone that were higher than 25 mcg—the lowest dose of levothyroxine available by prescription. And one contained more than 90 mcg—slightly less than a doctor would prescribe for a patient whose thyroid gland had been removed.

We need only mcg of iodine per day in our diet, according to the Institute of Medicine. But ingesting excess iodine can cause health problems. It is particularly worrisome for people with thyroid nodules—bumps on the thyroid glands that can be very small and often go unnoticed.

Conversely, studies also show that too much iodine more than around mcg per day can cause the thyroid to slow down or even stop producing hormones in certain people—the opposite effect of what many people hope these supplements will do for them.

That can result in weight gain and fatigue, and can increase your risk of cardiovascular disease ," Lipman says. Yet many supplements contain more than mcg of iodine.

For example, both Enzymatic Therapy's Metabolic Advantage and Whole Foods' Thyroid Complete contain mcg per two-capsule serving. Follow the recommendation on the labels and swallow two capsules three times a day and you've ingested mcg of iodine—enough to cause health problems in certain people if taken long term.

Kelp, a type of seaweed that is often marketed for thyroid health, is loaded with iodine. For example, a serving one drop of Liquid Kelp, a dietary supplement promoted for "Thyroid Gland Support," contains mcg of iodine.

But if you take a supplement that contains kelp, plus a multivitamin, such as GNC Women's Ultra Mega One Daily containing mcg of iodine, and also use iodized salt that contains mcg of iodine per teaspoon, it's easy to consume far more iodine than your thyroid needs—or that is healthy.

Many companies have started to market supplements for thyroid health. Some people with thyroid disorders may be deficient in specific nutrients, and increasing their levels may be beneficial.

However, taking supplements could also lead to serious health risks in people with thyroid disorders or healthy thyroids. A person should contact their doctor before taking any thyroid supplement.

More and more retailers are offering over-the-counter OTC supplements with labels declaring that they promote thyroid health, for example, providing energy or aiding weight loss. According to a article , most of these claims have no scientific basis, and some of the products could contain ingredients that may be potentially harmful to people with certain thyroid conditions.

In people with healthy thyroids, taking additional nutrients may raise their risk of thyroid complications. This article examines the pros and cons of taking thyroid supplements and the effect of specific nutrients on thyroid health.

It will also explain which supplements may be beneficial for certain thyroid disorders. According to the British Thyroid Foundation , no specific dietary supplements can help treat thyroid disorders. The best way to promote thyroid health is to follow a balanced diet that includes the correct levels of necessary nutrients.

However, taking additional nutrients in supplement form may help promote thyroid health in some people who find it challenging to follow a balanced diet, including:. A person must contact their doctor before taking any nutritional supplements.

A doctor can help identify the correct dosage and determine whether the supplements may affect thyroid blood test results. Consuming high amounts of some nutrients can adversely affect thyroid health, cause side effects, or have general health risks.

Learn more about thyroid hormones and levels here. The following nutrients can affect thyroid health in a variety of ways:. Iodine deficiency can cause thyroid disorders. People with a healthy thyroid must have proper levels of iodine in their bodies.

The recommended intake of iodine per day is relatively small, at micrograms mcg for people over 19 years old. However, teens and people who are pregnant require a slightly higher dose at mcg. And those who are breastfeeding need mcg. Taking too much iodine in the form of supplements can cause hypothyroidism, or an underactive thyroid, and hyperthyroidism, or an overactive thyroid.

In people with hypothyroidism and hyperthyroidism , taking iodine supplements can be unnecessary or potentially harmful. Doctors typically prescribe medications containing hormones T3 and T4. The thyroid gland uses iodine to make these hormones. However, some commercially available supplements contain a higher dosage of T3 and T4 than doctors prescribe.

This can lead to iatrogenic thyrotoxicosis, which can be fatal. Sources of iodine naturally available in food include :. Learn about signs of iodine deficiency here. A person should avoid supplements and natural boosters that contain kelp. It could have adverse effects on thyroid function. The body requires selenium for antioxidant function and the metabolism of thyroid hormones.

A deficiency of selenium can lead to thyroid dysfunction. However, high selenium intake in people without a deficiency may cause various conditions, such as hyperglycemia , atherosclerosis , or cancer.

Dietary sources of selenium include :. Learn more about foods that contain antioxidants here. The body requires zinc for thyroid function. Zinc plays a role in the synthesis and metabolism of thyroid hormones. Statin side effects Statins Statins: Do they cause ALS?

Symptom Checker Thyroid disease: Can it affect a person's mood? Lifestyle changes to improve cholesterol Trans fat Treatment-resistant depression Tricyclic antidepressants and tetracyclic antidepressants Triglycerides: Why do they matter?

Vitamin B and depression VLDL cholesterol: Is it harmful? Show more related content. Mayo Clinic Press Check out these best-sellers and special offers on books and newsletters from Mayo Clinic Press. Mayo Clinic on Incontinence - Mayo Clinic Press Mayo Clinic on Incontinence The Essential Diabetes Book - Mayo Clinic Press The Essential Diabetes Book Mayo Clinic on Hearing and Balance - Mayo Clinic Press Mayo Clinic on Hearing and Balance FREE Mayo Clinic Diet Assessment - Mayo Clinic Press FREE Mayo Clinic Diet Assessment Mayo Clinic Health Letter - FREE book - Mayo Clinic Press Mayo Clinic Health Letter - FREE book.

FAQ Home Hypothyroidism Should I take iodine supplements. Show the heart some love! Give Today. Help us advance cardiovascular medicine.

Find a doctor. Explore careers. Sign up for free e-newsletters. About Mayo Clinic. About this Site. Contact Us. Health Information Policy. Media Requests. News Network.

Price Transparency. Medical Professionals. Clinical Trials. Mayo Clinic Alumni Association. Refer a Patient. Executive Health Program. International Business Collaborations. Supplier Information. Admissions Requirements.

Degree Programs. Research Faculty. International Patients. Financial Services. Community Health Needs Assessment. Financial Assistance Documents — Arizona. Financial Assistance Documents — Florida.