Best Iodine Supplement: How to Choose the Right One for Your Needs

Iodine is one of those essential nutrients that doesn’t get enough attention—but it should. This trace mineral is critical for thyroid function, hormone balance, and overall metabolic and reproductive health. 

Without enough iodine in your diet or supplement routine, you can struggle with fatigue, brain fog, weight gain, and even hormone imbalances. For women in particular, iodine is needed to support thyroid health, pregnancy, breast health, and menopause. But with so many options on the market, you may be wondering: what is the best form of iodine to take? 

This article will cover the benefits and roles of iodine, the recommended intake for different stages of life, available supplement forms, and tips for choosing the best iodine supplement based on your age and goals.

What Is Iodine and What Is It Used for in the Body?

Iodine is a trace mineral that the body cannot produce on its own, meaning it's “essential” and must come from food or supplements. 

What is iodine used for in the body? It's primarily utilized by the thyroid gland¹ to produce thyroid hormones (T3 and T4), which have the job of regulating your metabolism, energy, and hormone balance, in addition to creating enzymes and proteins.

Iodine’s Key Functions in the Body:

While we often think of the iodine-and-thyroid connection, iodine does more than support thyroid health. Here's more about its key functions:

• Supports thyroid health: Iodine is essential for producing thyroid hormones, which are the backbone of your metabolism. Thyroid hormones also contribute to fertility, your mood and energy levels, your weight, and much more.

• Aids in cognitive function: Iodine deficiency has been linked to cognitive symptoms including brain fog, poor concentration, and developmental delays in children. Additionally, low iodine intake which is associated with poor thyroid health can contribute to mood-related symptoms like depression and anxiety.

• Promotes hormone balance: Iodine contributes to breast health, ovarian function, menstrual cycle regulation, and fertility.

• Supports pregnancy and fetal development: Pregnant women need higher levels of iodine to support fetal brain and nervous system development. Children also need iodine for normal growth², metabolic processes, and cognitive development.

• Acts as an antioxidant: Iodine helps detoxify heavy metals and protect against oxidative stress in the body, lowering the risk for certain conditions.

Roles & Health Benefits of Iodine

1. Iodine for Thyroid Health

Iodine is a must-have for thyroid function, as the thyroid gland needs iodine to produce thyroxine (T4) and triiodothyronine (T3). Without enough iodine, the thyroid can become underactive (hypothyroidism), leading to fatigue, weight gain, hair thinning, and a sluggish metabolism, among other symptoms.

However, for those with Hashimoto’s thyroiditis, iodine supplementation requires caution (more on that below), as too much iodine can backfire and worsen symptoms.

2. Iodine for Pregnancy and Breastfeeding

Pregnant and breastfeeding women have higher iodine needs, as iodine is crucial for fetal brain and nervous system development. Iodine deficiency during pregnancy is linked to cognitive impairments and developmental issues in infants, so it's crucial to ensure you're consuming enough when TTC or pregnant.

The CDC³ and World Health Organization recommend that pregnant and breastfeeding women take a multivitamin or prenatal supplement with iodine every day. The iodine RDA for pregnant women⁴ is 220 mcg per day and 290 mcg for breastfeeding women compared to 150 mcg for adults over 18.

3. Iodine for Breast Health

Iodine is highly concentrated in breast tissue and plays a key role in maintaining breast health and hormone balance. 

Women with iodine deficiency are susceptible to experiencing breast tenderness and cyst formation. Studies suggest iodine may help reduce fibrocystic breast changes and support estrogen metabolism, which helps to keep breasts healthy, particularly as you age.

4. Iodine for Menopause

During menopause, iodine helps to maintain hormone balance and thyroid function, both of which shift as estrogen levels fluctuate. Consuming adequate iodine can often help alleviate menopausal symptoms like fatigue, mood swings, and weight changes.

Iodine also supports bone health and cognitive function, both of which can decline with age and become more important to protect during menopause and beyond.

Is Iodine Deficiency Common?

Many people living in developed countries such as the U.S. are thought to consume enough iodine⁵, assuming they eat a varied diet and adequate calories. Most Americans obtain most of their iodine from iodized salt and milk⁶, as well as fortified grains, beef, and chicken.

That said, some people do not consume enough iodine, and there are several reasons why:

• Declining soil iodine levels: Modern agricultural practices have depleted iodine content in the soil, reducing iodine levels in many plant-based foods.

• Less consumption of iodine-rich foods: Many people don't eat iodine-rich foods on a regular basis, like seaweed, fish, and dairy, especially those following vegan or dairy-free diets.

• Reduction in iodized salt use: While iodized salt was introduced to combat deficiency, many health-conscious people and food manufacturers have switched to using sea salt or Himalayan salt, which contains little to no iodine.

• Environmental factors: Exposure to bromine, fluoride, and chlorine (found in processed foods, drinking water, and household products) can interfere with iodine absorption.

• Increased iodine needs: Pregnant and breastfeeding women require higher iodine intake, yet studies show many fail to meet these needs, increasing the risk of thyroid issues for both mother and baby.

Overall, people who don't use iodized salt when cooking—especially those with limited seafood or dairy intake—may benefit from taking an iodine supplement to maintain healthy levels.

Best Sources of Iodine

Natural food sources of iodine⁷ include:

• Seaweed (kelp, nori, dulse, wakame), which are among the richest sources of bioavailable iodine
• Fish and shellfish, including wild-caught cod, shrimp, and tuna
• Dairy products, including milk, yogurt, kefir, and cheese contain iodine due to cow feed supplementation
• Eggs, especially the yolks
• Beef liver
• Chicken
• Iodized salt, a common dietary source, though not always reliable for adequate intake
• Infant formula (which isn't necessarily “natural” but contains added iodine)

Interestingly, goitrogens—which are compounds found in foods such as brussel sprouts, kale, cabbage, cauliflower, radishes, and broccoli—can block iodine from being absorbed⁸. Therefore, it's best to eat these foods in moderate amounts but so aim for variety in your diet.

Related: What to Eat for Thyroid Health + One Day Thyroid Meal Plan

What Is the Best Iodine Supplement? (Forms and Bioavailability)

What's the best type of iodine supplement to take? When choosing an iodine supplement, bioavailability matters—because if your body can't actually metabolize and use the iodine, it doesn't serve much purpose.

The most common forms of supplemental iodine include:

• Potassium iodide: highly absorbable and commonly used in iodine supplements.

• Sodium iodide: another absorbable form but less common.

• Molecular iodine (I2): often used to support breast health.

• Lugol’s iodine: a mix of potassium iodide and iodine, often used for thyroid support.

• Nascent iodine: an easily absorbed, highly active form of iodine

If you’re looking for a complete thyroid support supplement, consider my Thyroid Support formula, which includes a balanced amount of iodine coupled with selenium, zinc, and adaptogenic herbs (like American ginseng) for optimal thyroid function. This combination helps maintain healthy cortisol, blood glucose, and insulin levels, along with a balanced conversion of peripheral thyroid hormone.

Related: Best Supplements and Nutrients for Thyroid Support

RDA of Iodine

Below is the daily recommended intake⁹ (RDA) of iodine (in mcg) based on life stage:

• Infants (0-6 months): 110 mcg
• Infants (7-12 months): 130 mcg
• Children (1-8 years): 90 mcg
• Children (9-13 years): 120 mcg
• Teens (14-18 years): 150 mcg
• Adults: 150 mcg
• Pregnant Women: 220 mcg
• Breastfeeding Women: 290 mcg

The “upper limit” of iodine (the amount that's safe to take each day) is 1,100 mcg per day¹⁰. Taking more than this can potentially cause thyroid dysfunction and should be avoided.

Should I Take Iodine? Who It's Best For

While we all need a certain amount of iodine (at least 150 mcg per day) to meet our needs, some people can benefit from additional iodine or should be extra cautious about consuming enough. This includes:

• Pregnant or breastfeeding women who need extra iodine for fetal and infant brain development.

• Those with low iodine intake¹¹ (especially if they don’t eat seafood, eggs, beef, chicken, or dairy).

• People with hypothyroidism (but you should check with a doctor first to make sure you're taking an appropriate amount). An iodine deficiency of less than 10-20 mcg a day can lead to inadequate thyroid hormone production and hypothyroidism.

• Women with fibrocystic breasts looking to support breast health.

• Those who smoke.

Related: Understanding Hypothyroidism: Diagnosis and Treatment

Who Shouldn’t Take Iodine?

Iodine supplements are not recommended for everyone, such as those who are sensitive to its effects or those with certain thyroid conditions. People who should be cautious about supplementing with iodine include:

1. People with Hashimoto’s Thyroiditis

Is iodine good for Hashimoto’s thyroiditis or bad? The truth is, the thyroid needs iodine, but not without selenium in the case of autoimmune thyroid disease.

Hashimoto's is an autoimmune condition where the immune system mistakenly attacks the thyroid gland, leading to chronic inflammation and hypothyroidism. Excessive iodine intake can potentially trigger or worsen autoimmune attacks¹², leading to further thyroid damage.

High iodine levels can increase thyroid antibody production, which may accelerate the disease’s progression. Some people with Hashimoto’s benefit from small, controlled amounts of iodine, but it’s important to pair iodine with selenium to prevent oxidative stress in the thyroid.

If you have Hashimoto’s, work with a healthcare provider before taking iodine supplements to make sure you're taking the right amount and that it's benefiting you, not harming you.

Related: Healing Hashimoto's Thyroid Disease

2. Those with Hyperthyroidism

Hyperthyroidism is a condition where the thyroid produces too much thyroid hormone, leading to symptoms like rapid heartbeat, weight loss, and anxiety. Excess iodine can further stimulate the overactive thyroid, worsening symptoms.

In some cases, iodine therapy is used for treating Graves’ disease (an autoimmune form of hyperthyroidism), but it should always be monitored by a doctor.

3. Those Sensitive to Iodine

Some people experience negative reactions to iodine, even in small amounts. Allergic reactions may include rashes, swelling, or difficulty breathing. Iodine sensitivity can also cause digestive discomfort, nausea, or skin irritation. If you have a history of iodine sensitivity, avoid high-dose iodine supplements and monitor your intake from food sources.

4. People Taking Certain Medications

Iodine supplements can interact with certain medications, including blood pressure medications and diuretics, such as lisinopril, spironolactone, and amiloride, causing a dangerous buildup of potassium in the blood (hyperkalemia).

If you take thyroid medications, talk to your provider about your iodine needs before beginning to supplement.

5. People Consuming High Amounts of Iodine in Their Diet

If you already consume large amounts of iodine-rich foods, like seaweed or iodized salt, excess iodine supplementation may not be necessary and could cause thyroid dysfunction. 

Too much iodine can lead to thyroid hormone imbalances, sometimes triggering iodine-induced hyperthyroidism or hypothyroidism. The body has a delicate balance for iodine regulation, and too much can be just as harmful as too little.

Related: Is Iodine Bad for Hypothyroidism? And 10 Signs You Have Hypothyroidism

Potential Iodine Supplement Side Effects

While iodine supplements can provide benefits for certain people, they can also cause side effects in some cases. Iodine supplement side effects can sometimes include:

• Thyroid dysfunction: Excess iodine can cause hypothyroidism or hyperthyroidism, depending on individual sensitivity.
• Worsening of Hashimoto’s: High iodine intake may increase thyroid antibodies and trigger autoimmune flares.
• Digestive issues: Nausea, stomach pain, or diarrhea
• Skin reactions: Rashes, acne, or irritation in sensitive individuals.
• Iodine-induced goiter: Enlarged thyroid gland due to excessive or imbalanced iodine intake.
• Metallic taste: Some people report a strong, unpleasant taste when taking iodine supplements.
• Allergic reactions: Swelling, itching, or difficulty breathing in those with iodine sensitivity.
• Heart palpitations: High doses may overstimulate the thyroid, leading to rapid heartbeat and anxiety.
• Burning sensation in mouth or throat: Rare, but possible with high-potency iodine solutions.

If any of these symptoms occur, it's best to reduce intake and consult a healthcare provider.

When to Take Iodine and Other Tips for Supplementing

To gain the most benefits from an iodine supplement, keep these tips in mind:

• Take iodine in the morning to align with natural thyroid hormone production.
• Pair iodine with selenium if possible since selenium helps prevent iodine-induced thyroid dysfunction.
• Avoid excessive doses since too much iodine can suppress thyroid function or trigger autoimmune flares.
• If using Lugol’s iodine or nascent iodine, start with low doses and increase gradually.

Final Thoughts on the Best Iodine Supplement for Your Needs

• Iodine is essential for thyroid health, pregnancy, hormone balance, and breast health, but it’s important to supplement wisely. 
• If you’re asking, “Should I take iodine supplements?”, the answer depends on your diet, thyroid function, and health status.
• For most women, a high-quality iodine supplement—like the Thyroid Support formula, which includes iodine along with other key thyroid nutrients—can help support metabolism, energy, and overall well-being. 
• Always check with your healthcare provider before starting iodine supplementation, especially if you have thyroid disease.

References

1. https://nutritionsource.hsph.harvard.edu/iodine/ ↩︎
2. https://www.who.int/data/nutrition/nlis/info/iodine-deficiency ↩︎
3. https://www.cdc.gov/breastfeeding-special-circumstances/hcp/diet-micronutrients/iodine.html ↩︎
4. https://www.thyroid.org/ata-statement-on-the-potential-risks-of-excess-iodine-ingestion-and-exposure/ ↩︎
5. https://www.ncbi.nlm.nih.gov/books/NBK222323/ ↩︎
6. https://www.ars.usda.gov/ARSUSERFILES/80400535/DATA/IODINE/IODINE%20DATABASE_RELEASE_2_DOCUMENTATION.PDF ↩︎
7. https://nutritionsource.hsph.harvard.edu/iodine/ ↩︎
8. https://www.cdc.gov/breastfeeding-special-circumstances/hcp/diet-micronutrients/iodine.html ↩︎
9. https://www.ncbi.nlm.nih.gov/books/NBK222323/ ↩︎
10. https://www.thyroid.org/ata-statement-on-the-potential-risks-of-excess-iodine-ingestion-and-exposure/ ↩︎
11. https://emedicine.medscape.com/article/122714-guidelines?form=fpf ↩︎
12. https://lpi.oregonstate.edu/mic/minerals/iodine ↩︎