The 5 Best Thyroid Supplements of 2023, According to a Dietitian
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Nature’s Made Vitamin D provides 2,000 IU of D3 and is USP Verified
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Fact checked by Rich ScherrMedically reviewed by Danielle Weiss, MD
The thyroid is a butterfly shaped gland found in the front of your neck, producing hormones that control many functions, including heart rate, digestion, mood, and metabolism. People with an underactive thyroid—known as hypothryoid—may feel fatigued or unusually cold, experience weight gain, hair loss, or dry skin, among other symptoms. This can be caused by anything from an autoimmune condition known as Hashimoto's Disease to medications, lifestyle, and nutrient deficiencies. Your thyroid can also be overactive—known as hyperthyroid—which leads to opposite symptoms such as rapid weight loss, trouble sleeping, nervousness, and mood swings.
“There are many different scenarios in which people could benefit from supplements for thyroid health, but it ultimately depends on the individual's case. Before starting any supplements for thyroid health, it's important to make sure you're addressing the really important diet and lifestyle fundamentals that impact the thyroid,” says Jillian Greaves, MPH, RD, LDN. This includes eating balanced meals, eating enough, quality sleep, regular movement, and not smoking.
To know which supplements—if any—can improve your thyroid health, it’s essential to understand the underlying reason for your symptoms. “Whether thyroid imbalances are autoimmune or not is a huge factor in determining the correct approach to treatment,” says Melissa Groves Azzaro, RDN, LD, owner of the Hormone Dietitian. To choose the best thyroid supplements, our dietitian thoroughly reviewed the latest research on thyroid health and interviewed colleagues who specialize in thyroid and hormone health.
Before starting a supplement, it’s essential that you work with a healthcare provider to understand more about your individual situation. “I would not recommend that anyone start thyroid supplements blindly. We always want to make sure the supplement is needed, that it's helping to support the issue at hand, and that you are taking the right form and dose. Over-supplementing with certain nutrients can actually be harmful,” says Greaves.
Editor's Note
Our team of registered dietitians reviews and evaluates every single supplement we recommend according to our dietary supplement methodology. From there, a registered dietitian on our Medical Expert Board reviews each article for scientific accuracy. 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 which dosage to take.
Best Vitamin D: Nature Made Vitamin D3 2000 IU
Pros
USP Verified
Budget-friendly
Research-backed maintenance dose
Cons
Not suitable for soy-free or vegan diets
Nature Made Vitamin D3 is our top pick because it's USP-verified, budget-friendly, and comes in multiple dose options. Research suggests that vitamin D deficiency is linked to hypothyroidism, and one recent study showed that vitamin D supplementation significantly improved TSH (thyroid stimulating hormone) levels among people with hypothyroidism. There also appears to be a relationship between vitamin D deficiency and risk of Graves Disease (hyperthyroidism) and even thyroid cancer. It’s estimated that 30 percent of people living in the United States are vitamin D deficient and many more are considered insufficient.
Before starting a vitamin D supplement, it’s helpful to have your levels checked to ensure you’re taking the right dose for you. The recommended dietary allowance (RDA) is 600 IU for most adults, but emerging research suggests that we may actually need 2,000 IU to maintain adequate stores for health benefits beyond just bone health, and more to correct deficiency.
Nature Made Vitamin D3 provides 2,000 IU (50 micrograms) of vitamin D, but Nature Made also offers supplements that contain lower or higher doses depending on your needs. We like Nature Made supplements because they are budget-friendly and are USP verified; this means they are third-party tested for ingredient amounts and contaminants.
These soft-gels do contain soybean oil, which may not be appropriate for someone with a soy allergy, and they also contain gelatin, which is not vegan.
Price at time of publication: $11 ($0.12 per serving)
Key specs:
Active Nutrient: vitamin D3 | Dose: 2,000 IU | Servings per container: 90
Best Selenium: Now Foods Selenium 200 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
Our thyroid uses a significant amount of selenium, and some research shows that people with autoimmune thyroid diseases (both Hashimoto's and Graves) are more likely to have low levels of selenium. Preliminary studies indicate that selenium supplements may reduce thyroid antibodies associated with Hashimoto’s (hypothyroid).
Now Foods selenium contains 200 micrograms of selenomethionine, which is the form found in food and known to be one of the two forms that is most absorbable by humans (the other is selenocysteine). Most studies that have evaluated the benefits of selenium in relation to thyroid health have tested between 100 to 200 micrograms, with 200 micrograms being most common. Now Foods selenium is also a budget-friendly option that fits most dietary needs as it’s vegan, Kosher, Halal, and free from the top 8 allergens.
It’s important to note that the optimal range for selenium intake is narrow and too much selenium—even if some of it comes from food—can be harmful and actually make thyroid problems worse. The tolerable upper limit is 400 micrograms as established by the National Institutes of Health, and you’ll want to factor in both dietary and supplement sources of selenium.
Because some supplements have been shown to have higher amounts than is listed on the label, choosing a third-party verified product like this one, can be extra important for selenium supplements. As NOW Foods also does extensive in-house product testing, this product is doubly verified to contain what it says it contains without harmful contaminants. If you’re considering a selenium supplement, work with a healthcare provider to determine the best dose for you.
Price at time of publication: $19 ($0.11 per serving)
Key specs:
Active Nutrient: selenomethionine | Dose: 200 mcg | Servings per container: 180
Best Zinc: Thorne Research Zinc Picolinate, 30 mg
Pros
NSF Certified for Sport
Third-party tested
Zinc is the only ingredient
Cons
Dose may be higher than some needs
Zinc is a trace mineral that is important for thyroid health. Some preliminary reports suggest that zinc deficiency may be associated with hypothyroidism, and one study found that zinc supplements (along with other vitamins and mineral supplements) improved thyroid health markers among people with hypothyroidism. “If someone has a non-autoimmune thyroid condition driven by nutrient deficiencies, they would want to supplement any thyroid-supporting nutrients they are deficient in, such as zinc,” says Groves Azzaro.
Zinc is available in a variety of foods including seafood, beef, nuts, beans, and dairy. However, zinc deficiency or inadequacy is common among vegans, some vegetarians, and people with gastrointestinal disorders like inflammatory bowel disease. Vegans and vegetarians also need to consume more zinc than meat eaters because phytates found in many plant-based foods can reduce absorption.
If you aren’t getting enough zinc through diet, Thorne’s zinc picolinate is a good choice to help you meet your needs. It’s verified by two top third-party organizations — including NSF certified for Sport — which ensures that it doesn’t contain any harmful contaminants and that the label ingredients are accurate. As a third verification, Thorne does extensive third-party testing on all of its products.
It’s estimated that we absorb between 50 to 60 percent of zinc from supplements, so although the 30 mg found in this supplement is nearly three times the Recommended Dietary Allowance (RDA) for zinc, you’re likely not absorbing it all. It’s also still well below the tolerable upper intake level (UL) of 40 milligrams.
Thorne’s supplement contains only zinc, unlike many supplements that combine other nutrients with zinc, which may be unnecessary. It’s also gluten-free, dairy-free, and soy-free.
Price at time of publication: $18 ($0.30 per serving)
Key specs:
Active Nutrient: zinc picolinate | Dose: 30 mcg | Servings per container: 60
Related: The 7 Best Zinc Supplements of 2023
Best Iodine: Swanson Kelp
Pros
Third-party tested
Budget-friendly
Cons
May not be appropriate for someone with shellfish allergy
Iodine is an essential mineral required for thyroid health and iodine deficiency can cause hypothyroidism. While iodine deficiency is rare in the United States, the increased use of non-iodized table salt (such as sea salt and Himalayan salts) could lead to insufficiency (or less than optimal levels) in some people. In addition, people who don’t eat dairy, seafood, and eggs as well as pregnant and lactating people are at higher risk of insufficiency.
If you're not getting enough iodine through your diet, Swanson’s kelp supplement may be helpful in meeting your needs. It provides 225 micrograms of iodine from kelp (a type of seaweed), which is about 150 percent of adults' daily iodine needs and 100 percent of pregnant people’s needs. It has also been third-party tested for ingredient amounts and contaminants. This is important as iodine is well absorbed by the body, and the optimal range for thyroid health is narrow, so you want to ensure you’re not taking too much.
Be aware some multivitamins and prenatals contain iodine. If you’re taking other supplements, carefully check amounts to ensure you’re not exceeding the tolerable upper intake level established by the National Institutes of Health of 1,100 micrograms. Swanson’s kelp may contain remnants of shellfish, so this is not appropriate for someone with a shellfish allergy.
Price at time of publication: $10 ($0.04 per serving)
Key specs:
Active Nutrient: iodine from kelp | Dose: 225 mcg | Servings per container: 250
Important Note About Iodine Supplementation
Excess iodine is problematic for thyroid health and can exacerbate hypothyroid. If you’re concerned that you’re not getting enough iodine in your diet, work closely with a healthcare provider to determine if you are truly not getting enough and if a supplement is right for you.
Best Iron: Mary Ruth’s Liquid Iron
Pros
Third-party tested
Vegan, Non-GMO, and gluten-free
Form is gentler on gastrointestinal system
Cons
Some may not like the taste
Studies have linked iron deficiency to hypothyroid in both pregnant and non-pregnant people. While more research is needed to understand how supplements can support thyroid health, if you are deficient in iron, it could be contributing to non-autoimmune thyroid problems.
Mary Ruth’s Liquid iron contains 18 milligrams of ferrous bisglycinate chelate, a form that has been shown to be well-absorbed by the body, effective at repleting iron stores, and gentler on the gastrointestinal tract than some other forms of iron. It’s third-party tested, vegan, soy-free, and gluten-free. While it doesn’t contain any sugar, it does contain stevia as a sweetener.
Iron is known to interfere with the absorption of levothyroxine, a common medication to treat hypothyroid. Iron supplements should always be taken four hours apart from thyroid medications. It’s important to work with your healthcare provider to determine if an iron supplement is appropriate for you, as over-supplementation can be harmful.
Price at time of publication: $38 ($1.27 per serving)
Key specs:
Active Nutrient: iron bisglycinate | Dose: 18 mg | Servings per container: 30
Related: The 9 Best Iron Supplements of 2023
Are Thyroid Supplements Beneficial?
It depends. Whether or not a supplement will support thyroid health depends on the type of thyroid disorder and underlying reason for the disorder. “If someone's diet is lacking key nutrients needed for thyroid health it may be helpful to supplement with thyroid supporting nutrients,” says Greaves. However, taking supplements when they are unnecessary can actually have the opposite effect. For example, excess iodine can actually make thyroid problems worse.
Understanding the type of disorder you have is also essential. That’s why working with a healthcare provider for a proper diagnosis with lab work is the first step to determining whether supplements will be helpful. “Typically for someone with autoimmune hypothyroid, we're looking at selenium, vitamin D, inositol, and any other deficiencies the person may have. For non-autoimmune thyroid, we may consider a multivitamin that contains adequate B vitamins, iodine, iron, selenium, zinc, and addressing any specific nutrient deficiencies that may be contributing [to the problem],” says Groves Azzaro.
Who May Not Benefit from Thyroid Supplements
It’s most important to understand your individual nutrient status and underlying reason for thyroid problems. The following groups of people may not benefit from supplements:
Those that have had their thyroid removed. If you’ve had a thyroidectomy due to thyroid cancer or other reasons, taking supplements to support thyroid health will not be beneficial.
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.
People who haven’t addressed important lifestyle factors. “Supplements will not produce much of a benefit if you are neglecting the fundamentals like eating enough, getting enough sleep, etc.” says Greaves.
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. There is no research to support combining multiple nutrients, and, in many cases, more is not better. Because some thyroid-supporting nutrients like selenium and iodine have narrow optimal ranges (and supplementing when unnecessary can be problematic), it’s best to understand which nutrients you need and can benefit from and choose supplements that meet your specific needs.
Vitamin B12: Research on the relationship between vitamin B12 and thyroid health is conflicting. Some studies suggest that people with hypothyroid are more likely to be deficient in B12 whereas others suggest no relationship. More research is needed to understand if supplements can support thyroid health. If you have a known B12 deficiency, talk to a healthcare provider about a supplement to support repletion. To better understand if you should be supplementing with B12, and, if so, which supplements to choose, take a look at our article covering the best B12 supplements.
Inositol: Inositol is a precursor to a messenger that helps produce thyroid stimulating hormone (TSH). Preliminary research suggests that inositol (also known as MYO-inositol) supplements may improve TSH and thyroid antibody levels. However, more research is needed to understand the safety and efficacy of supplementing with inositol in relation to thyroid health as well as proper dosing.
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 support supplements that are evidence-based and rooted in science. We value certain product attributes that we find to be associated with the highest quality products.
It's important to note that the FDA does not review dietary supplements for safety and effectiveness before they go to market. Our team of experts has created a detailed, science-backed methodology to choose the supplements we recommend.
We interviewed the following experts to get thyroid supplement recommendations:
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. However, it’s important to note:
Third party testing does not test to see if a product is effective or safe for everyone, and it does not ensure the supplement will not interact with other supplements or medications.
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. However, these certifications are difficult to obtain and/or expensive for manufacturers, so many companies choose not to get their products tested by one of these three organizations.
Sometimes products tested by these three companies are more expensive to try to offset the cost they pay for certification.
Just because a supplement is not tested by one of these three companies, it does not mean it’s a bad product. 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. In some cases, such as vitamin D, there is one form (D3) that is recommended. In other cases, such as iron, the best form for you may depend on your specific goals and health status. We reviewed top forms within each supplement recommendation, but we recommend discussing the best form of each supplement with a healthcare provider.
Ingredients & Potential Interactions
It is essential to carefully read the ingredient list and nutrition facts panel of a supplement to know which ingredients and how much of each ingredient is included, relative to the recommended daily value of that ingredient. Please bring the supplement label to a healthcare provider to review the different ingredients contained in the supplement and any potential interactions between these ingredients and other supplements and medications you are taking.
Some thyroid supporting nutrients like selenium, zinc, and iodine are combined with other vitamins, minerals, and herbs. Unless you have a known deficiency or additional need for other nutrients found in a supplement, it’s best to choose a supplement that contains just the nutrient you are looking for to avoid potential interactions with medications or over-consuming nutrients.
Some iron supplements also contain vitamin C, as vitamin C aids the absorption of iron. For most people, this is considered safe as long as you’re not exceeding the tolerable upper intake level for vitamin C, which is 2,000 mg for adults.
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.
Each supplement discussed in this article has a different RDA. Please review those amounts discussed within each of the individual supplement recommendations.
How Much is Too Much?
It’s important to ensure that you aren’t taking more of any individual nutrient than the tolerable upper limit established by the National Institute of Health Office of Dietary Supplements. Some nutrients, such as vitamin D, can be stored in fat tissue and can be dangerous when consumed in excess through supplementation. Minerals such as iron, iodine, selenium, and zinc can also lead to serious side effects if consumed in excess.
“Some beneficial nutrients for thyroid health can actually be harmful when taken in excess. Over-supplementing with nutrients like iodine, selenium, or iron can be harmful and make thyroid issues worse. This is why it's so important to make sure you're taking the right form and dose of any nutrients,” says Greaves.
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?
“Most thyroid medications should be taken on an empty stomach, away from any other medications or supplements,” says Groves Azzaro. For example, levothyroxine is a common medication used to treat hypothyroid, and iron supplements are known to interfere with effectiveness of this medication. If you are taking thyroid medication, always check with a healthcare provider before starting any supplements and to create the best plan for when to take them.
Can I take collagen supplements with thyroid medication?
“Thyroid medication is preferably taken on an empty stomach 30-60 minutes before any food, so I recommend the same guideline with collagen supplements to avoid any potential disturbances with the absorption of the medication,” says Greaves.
What supplements affect thyroid tests?
“Biotin is well-known to impact the results of thyroid testing and should be avoided before testing,” says Groves Azzaro. Biotin is found in many supplements including B-complex supplements, prenatals, multivitamins, and supplements marketed to support hair, skin, and nails. It may also be found in combination with collagen powders or other collagen supplements.
Are thyroid supplements safe?
The safety of thyroid supplements depends on the type of supplement, the dose, and the individual taking the supplement. It’s important to work closely with a healthcare provider before starting any supplement to support your thyroid to determine whether or not it’s safe for you.
What other ways can I boost my thyroid naturally?
Thyroid health is largely dependent on lifestyle, and a lot can be done to support your thyroid before considering supplements. Start by ensuring you are getting adequate sleep and managing stress. Diet and exercise also play an important role.
“I always recommend making sure you're eating enough calories first and foremost. Under-eating puts significant stress on the body and directly impairs thyroid function,” says Greaves. For example, low-calorie diets or diets that eliminate entire food groups can make it hard to meet your nutritional needs and support thyroid health. Having too high or too low blood sugar can also interfere with thyroid health. Greaves says, “If blood sugar is imbalanced, this will create barriers to success with any type of thyroid treatment.”
Graves recommends “eating consistent meals every 3-5 hours throughout the day and [aiming] to include a balance of protein, healthy fats, fiber rich starchy carbs, and non-starchy vegetables at meals to support blood sugar stability." Lastly, we recommend adding more nutrient-dense whole foods that include thyroid supporting nutrients like zinc, selenium, and iodine.
Read Next: The 5 Best Fiber Supplements of 2023, According to a Dietitian
