The 5 Best Thyroid Supplements of 2023, According to a Dietitian

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.

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