Supplements and Thyroid Health: What to Know

Thyroid disorders — such as hypothyroidism, hyperthyroidism, and thyroid cancer — are widespread. For instance, up to 7% of people in the U.S. have hypothyroidism, a condition where the thyroid fails to produce sufficient thyroid hormones (1).

Treatment varies by diagnosis and commonly includes medications like thyroid hormone replacement, surgical approaches, and procedures such as radiation therapy for thyroid cancer.

Alongside standard medical care, evidence indicates that dietary strategies and certain supplements can support management of some thyroid disorders.

That said, some supplements can be harmful rather than helpful for thyroid function.

This article reviews how supplements may aid particular thyroid conditions and which products to approach with caution.

Supplements for overall thyroid support

Walk down the supplement aisle in many health stores and you’ll likely find products labeled to “support thyroid health.”

Because thyroid problems are common, numerous companies now market formulas aimed at bolstering thyroid function.

While a number of these offerings are benign, other thyroid-targeted supplements can produce adverse effects and even damage the gland.

Before discussing why thyroid-specific blends aren’t ideal for everyone, it helps to outline the nutrients the thyroid requires for healthy function. Key nutrients include:

• Selenium. This trace element is essential for thyroid hormone synthesis and helps shield the gland from oxidative injury. The thyroid accumulates selenium, and deficiency can impair thyroid function (2).
• Iodine. Iodine is vital for making thyroid hormones. In fact, iodine’s primary biological role is thyroid hormone production: T3 and T4 contain iodine atoms. Lack of iodine causes thyroid disorders (3, 4).
• Zinc. Zinc is involved in thyroid hormone synthesis. Appropriate zinc levels are needed to maintain healthy T3, T4, and TSH concentrations (5).
• Iron. Iron is required for converting T4 into the active hormone T3. Iron deficiency is linked to thyroid dysfunction (6).

Other micronutrients — including B vitamins and vitamins A and E — also support thyroid health. Lacking one or more of these nutrients can negatively impact thyroid function and raise the risk of thyroid disease (7, 8, 9, 10).

For most individuals, eating a varied, nutrient-rich diet centered on whole foods is sufficient to preserve thyroid health.

However, certain groups may require supplemental vitamins, minerals, or other nutrients to maintain general health and support the thyroid.

These groups include people following restrictive diets, pregnant or breastfeeding individuals, and people with existing thyroid or other medical conditions.

Do you need thyroid-specific supplements?

A nutrient-rich diet is crucial for thyroid wellness, and deficiencies can precipitate thyroid problems.

Yet, for those without thyroid disease who eat a balanced, nutrient-dense diet, thyroid-specific supplements are usually unnecessary.

Indeed, many products marketed to enhance thyroid function can be unsafe.

For example, some thyroid supplements deliver large amounts of iodine and even contain thyroid hormones. Using these products can produce dangerous side effects and induce thyroid dysfunction in otherwise healthy people (11).

One analysis of 10 thyroid supplements detected measurable T3 and T4 in most products; a few contained hormone levels exceeding typical prescribing doses for hypothyroidism (11).

Taking such supplements can raise circulating thyroid hormones and trigger hyperthyroid symptoms, which may lead to serious complications (12, 13, 14).

Moreover, excessive iodine intake from supplements can provoke hypothyroidism in susceptible people (12, 13, 14).

Thyroid-formulated supplements may also be risky for people who already have thyroid disease.

Those with diagnosed thyroid conditions have individualized requirements, and using over-the-counter thyroid blends can disrupt function and worsen symptoms.

Therefore, people with and without thyroid disorders should generally avoid thyroid-promoting supplements. Instead, consult a healthcare professional to create a safe, personalized plan based on your specific health needs.

Summary: It’s wise to avoid dietary supplements marketed to support thyroid health; these products can cause harm in people both with and without thyroid disease.

Supplements for Hashimoto’s disease

Hashimoto’s thyroiditis is the leading cause of hypothyroidism in the U.S. It’s an autoimmune illness where the immune system generates antibodies that attack the thyroid, often resulting in scarring of thyroid tissue (15).

Hashimoto’s is linked to many symptoms, such as weight gain, fatigue, hair thinning, anemia, constipation, cold sensitivity, joint aches, dry skin, mood shifts, concentration problems, and more (15).

Beyond medication, dietary and lifestyle changes can help limit thyroid damage and improve symptoms and life quality in people with Hashimoto’s.

People with Hashimoto’s are also more prone to deficiencies in certain nutrients, which can exacerbate symptoms.

Research indicates the following supplements may be helpful in Hashimoto’s:

• Selenium. Trials suggest 200 mcg daily of selenium may reduce thyroid antibody levels and improve mood in people with Hashimoto’s (16, 17).
• Myo-Inositol. Inositol, a sugar alcohol involved in thyroid signaling, may improve thyroid function when combined with selenium. Studies used 600 mg Myo-Inositol plus 83 mcg selenium daily (18, 19).
• Zinc. Zinc is necessary for thyroid hormone production; deficiency can contribute to hypothyroidism. Supplementing with about 30 mg daily, alone or with selenium, may support thyroid function in Hashimoto’s (20, 21).
• Vitamin B12. B12 deficiency is common in those with Hashimoto’s. A B12 or B-complex supplement can prevent and treat deficiency and maintain adequate levels (22, 23).
• Magnesium. Low magnesium may raise the risk of Hashimoto’s and is associated with higher thyroid antibody titers. Correcting magnesium deficiency can improve symptoms (24, 25).
• Iron. Many women with Hashimoto’s have low iron or iron-deficiency anemia, which impairs thyroid function. Iron supplementation may be needed to restore optimal levels (26).
• Vitamin D. People with Hashimoto’s are more frequently vitamin D–deficient than the general population, and low vitamin D can adversely affect thyroid health (22, 27).
• Curcumin. Curcumin may protect the thyroid from oxidative injury, and when combined with other anti-inflammatory agents it may help shrink thyroid nodules often seen in Hashimoto’s (28, 29).
• Vitamin C. Some evidence suggests vitamin C supplementation can reduce thyroid antibody levels in Hashimoto’s (30).

Other supplements may also be helpful, but the nutrients listed above have the strongest evidence in Hashimoto’s management.

Summary: Evidence suggests certain supplements — including selenium, zinc, iron, and vitamins D and B12 — can be useful for people with Hashimoto’s disease.

Supplements for Graves’ disease

Graves’ disease is the main cause of hyperthyroidism in the U.S. Like Hashimoto’s, it is an autoimmune disorder.

In Graves’ disease, immune attack causes the thyroid to overproduce hormones. The condition can also cause thyroid enlargement (thyromegaly) (31).

Symptoms of Graves’ disease include weight loss, palpitations, shortness of breath, diarrhea, eye discomfort and irritation, fatigue, weakness, irregular menses, insomnia, anxiety, and more (32).

Treatments for Graves’ include surgery, antithyroid drugs, and radioactive iodine therapy (RAI) (32).

Similar to Hashimoto’s, dietary changes may help ease symptoms and improve quality of life for people with Graves’ disease (33).

The following supplements may be beneficial for Graves’ disease:

• Selenium. Selenium deficiency is associated with increased risk of Graves’. A review found that daily selenium (100–300 mcg) improved thyroid function at 6 months, though the benefit diminished by 9 months (34).
• Vitamin D. People with Graves’ are more likely to be vitamin D–deficient. Correcting deficiency through supplementation may support thyroid health (35, 36, 37).
• L-carnitine. Hyperthyroidism depletes carnitine stores, which are important for cellular energy. L-carnitine supplementation may help reduce symptoms and improve quality of life in hyperthyroid patients (38, 39).
• Vitamin B12. People with Graves’ have a higher risk of B12 deficiency. A quality B12 or B-complex supplement can help maintain adequate B12 status (40, 41, 42).

Other supplements may be useful, and it’s best to collaborate with an experienced healthcare provider to design a regimen tailored to your needs.

Summary: Research indicates vitamin D, selenium, L-carnitine, and vitamin B12 may offer benefits for people with Graves’ disease.

Supplements for thyroid cancer

Thyroid cancer is relatively uncommon, representing about 1–4% of cancers in the U.S. Most thyroid cancers arise from follicular cells — these account for up to 95% of thyroid malignancies (43).

Management of thyroid cancer can include surgery, radiation, TSH suppression, radioactive iodine (RAI), total thyroidectomy, and palliative care when curative treatment is not possible.

Alongside conventional therapy, dietary measures, supplements, and lifestyle changes may support treatment and quality of life for those with thyroid cancer.

Preclinical and in vitro research suggests omega-3 fatty acids, curcumin, L-carnitine, quercetin, melatonin, resveratrol, selenium, inositol, zinc, and vitamins C, E, A, and D might have beneficial effects in thyroid cancer (44, 45, 46).

Low iodine intake is associated with increased thyroid cancer risk, and correcting iodine deficiency may protect against more aggressive disease forms (47).

However, despite the known anticancer properties of nutrients like vitamin D and selenium, human trials in thyroid cancer patients are limited (47, 48).

More clinical research is needed before routine supplement recommendations can be made for thyroid cancer care (47, 49).

The safest approach is to consult your oncology team or a registered dietitian experienced in cancer care to determine whether supplements are appropriate given your diet, health, and cancer treatments.

Summary: Although some supplements show promise in lab studies, human research on supplements for thyroid cancer is sparse; check with your medical team before taking supplements.

Precautions with thyroid supplements

As noted earlier, avoid thyroid-specific supplement blends unless prescribed by your clinician.

These products can impair thyroid health and may even induce thyroid disorders (11, 12, 13, 14).

Nevertheless, a number of vitamins, minerals, and other dietary supplements have been demonstrated to enhance thyroid function, reduce symptoms, and improve quality of life in people with thyroid disease.

If you have Hashimoto’s, Graves’, thyroid cancer, or another thyroid-related condition, it’s important to work with a qualified clinician who specializes in thyroid disorders.

This is particularly crucial if you’re taking medications, since many supplements — especially herbal preparations — can interact with prescription drugs and cause dangerous effects.

Finally, purchase supplements from reputable manufacturers that have their products independently tested for potency and purity by organizations such as USP and NSF International.

Summary: If you’re considering supplements for a thyroid condition, consult a knowledgeable healthcare provider who can recommend options tailored to your needs and safety.

The bottom line

Evidence indicates that several vitamins, minerals, and other nutrients may benefit people with certain thyroid disorders.

However, supplement plans should be individualized based on your particular requirements and medical status.

If you’re interested in using supplements to manage a thyroid condition, work closely with a qualified healthcare professional to ensure safety and effectiveness.

Useful supplement shopping guides

• How to Choose High Quality Vitamins and Supplements
• How to Read Supplement Labels Like a Pro