Iodine is an essential mineral for proper function of your thyroid, which produces hormones that regulate everything from your body weight to your emotional stability and cognitive function.
It's also a common nutrition deficiency.
Iodine deficiency affects an estimated two billion people worldwide, and has only been fully controlled in five countries—all of them in central or northern Europe.
Keeping iodine levels in the correct range is critical for pregnant women, as iodine deficiency is associated with a range of very serious health problems in infants, but the importance of iodine is not limited to women of childbearing age.
Iodine deficiency (and excess) in adults is associated with an increased incidence of thyroid problems, including both hypothyroidism and hyperthyroidism.
Fortunately, with a good iodine supplement, an iodine deficiency is easy to correct, thanks to its strong bioavailability.
If you want to ensure your thyroid hormone production isn’t hampered by an iodine deficiency, check out our rankings of the best iodine supplements on the market. Our research team has evaluated and sorted these products according to iodine content and production quality.
1. Nature’s Way Kelp
Nature’s Way delivers iodine in a natural and highly pure form: unprocessed kelp. This simple and natural source of iodine is surprisingly concentrated, with 300 micrograms of iodine per 600 milligrams of kelp in every capsule.
It’s a good choice if you want your iodine as close to its natural form as possible. With the solid dose and natural format, it’s the top overall iodine supplement.
2. J. Crow’s Lugol’s Solution
Among the liquid-based iodine solution, J. Crow’s is the best. It has a high concentration of iodine, and is used by many people with thyroid issues to address iodine deficiencies rapidly and effectively.
While it was originally developed to sanitize water, it’s easily mixed into shakes and smoothies, though it does leave a vaguely metallic taste in your mouth.
3. Zhou Thyroid Support with Iodine
Zhou Thyroid Support is one of the best ways to get iodine along with other supplements that can support your thyroid function, like selenium, zinc, and ashwagandha.
This is a complete package for thyroid support that comes along with 150 micrograms of iodine. For a comprehensive thyroid solution, it’s a great choice, but if all you need is iodine there are better ways to get it.
4. Pure Encapsulations Iodine
Pure Encapsulations makes a pretty straightforward iodine supplement that uses potassium iodide to provide 225 micrograms of iodine in a vegan-friendly cellulose capsule.
It’s hard to go wrong with this moderate-dosage and super-simple iodine supplement if all you need is a reasonable dosage.
5. Benevolent Liquid Iodine
Benevolent offers a liquid iodine supplement, which is useful for people who can’t or don’t want to take pills. The liquid supplement is also useful for mixing into shakes, smoothies, and meal replacements.
One drop contains 150 micrograms of iodine, which means this bottle will last you a long time. The only problem this supplement has is one shared with all liquid supplements: it’s hard to measure out a precise dosage, so you don’t exactly know how much iodine you’re getting.
6. Life Extension Sea-Iodine
Life Extension delivers iodine in a complex of kelp and bladderwrack extracts. The supplement has a total of 1000 micrograms of iodine per capsule, which makes it a great way to rapidly increase iodine levels in your body.
Because it’s delivered in a natural form, it’s more bioavailable and provides some ancillary nutrients found in the ocean-based sources of these two extracts.
However, given its very high iodine dosage, you should only use it if you get very little iodine elsewhere in your diet.
7. Dr. Mercola Iodine
Dr. Mercola sells a very minimalist high-dose iodine supplement. It delivers 1500 micrograms of iodine, though all of it is in the form of potassium iodide.
It may not have the benefits of naturally-sourced iodine supplements, but it’s still a solid way to rapidly deliver iodine to your body, even if it’s a fairly blunt tool for doing so.
8. RLC Labs iThroid
With 12500 micrograms of iodine per cellulose-based capsules, RLC Labs delivers a lot of iodine, both as potassium iodide and free iodine.
The dose is high, though it doesn’t offer quite the perks as some of the other high dose iodine supplements on the market.
However, the fact that this supplement exceed the recommended dietary intake of iodine set by the National Institutes of Health means that you should only use this if you’re specifically directed to take high dose iodine supplements.
9. Optimox Iodoral
If you know you need a high dose of iodine to correct a deficiency, Iodoral should definitely be your top choice. With a whopping 12500 micrograms of iodine, in both potassium iodide and pure iodine form, this supplement delivers a massive dose of iodine to rapidly boost iodine levels.
Like other high dose iodine supplements, you should not take this for prolonged periods, and it should not be used by pregnant women.
10. Global Healing Center Detoxadine
Global Healing Center sells a liquid form of iodine that is in its pure atomic state. While the company claims that this is an ideal form for use in detox regimens, other nutritionists counter that salt forms of iodine, like potassium iodide, are easier to absorb by adults.
That, combined with the intrinsic weakness of liquid supplements in low concentrations (i.e. that they are difficult to measure precisely) detracts from Detoxidine’s spot in the rankings.
Iodine supplement benefits and side effects
Iodine is a critical nutrient for producing thyroid hormones, which in turn determine everything from your mood to your weight to your cognitive function.
If you’re deficient in iodine, you’re not alone: billions of people have low iodine levels worldwide, despite the widespread addition of iodine to table salt.
According to research published in the Journal of Clinical Endocrinology & Metabolism, iodine intake has been declining in the United States in the last several decades, perhaps due to decreased use of sodium out of fears of increased blood pressure (1).
For some people, this can have negative consequences. However, iodine levels that are too high have health consequences too. It’s important to maintain the appropriate level of iodine for optimal health.
Iodine keeps your thyroid functioning properly. Thyroid disorders, like hypothyroidism, are directly linked to the prevalence of iodine deficiency. That’s according to research by Michael Zimmerman at the Swiss Federal Institute of Technology Zürich (2).
In an authoritative review that covered the detrimental effects of iodine deficiency at the population level, Zimmerman cited research that showed that chronically low iodine intake was linked to abnormal thyroid function, which has a number of negative health consequences, from mental retardation in infants and children to fatigue, weakness, and emotional instability in adults.
Iodine supplementation during pregnancy improves fetal health. During pregnancy, iodine levels play a vitally important role in cognitive development, so much so that medical authorities recommend iodine supplementation (either in supplemental iodine tablets or in fortified table salt) among women who are pregnant or intend to become pregnant in the near future (3).
If iodine levels are not optimal during pregnancy, there is irreversible damage to the cognitive abilities of your infant, according to research conducted by Maureen Black at the University of Maryland School of Medicine (4).
Women who are pregnant should not take too much iodine. As with many supplements, there can be such a thing as too much of a good thing.
A large cohort study conducted in China found that excessive iodine intake is also linked with hypothyroidism, possibly due to an increased risk of autoimmune problems affecting the thyroid (5).
High dose iodine supplements should not be taken by pregnant women unless under a doctor’s orders because of the risks of excessive iodine intake.
Iodine supplements can protect you from cancer in the event of a nuclear accident. Far-fetched? Perhaps, but iodine supplements are stockpiled in all major cities for precisely this reason.
After accidents at nuclear power production facilities, radioactive iodine is released into the atmosphere. When it gets into your body, it’s rapidly absorbed by your thyroid, and can cause thyroid cancer.
Following the Chernobyl disaster in the USSR, iodine supplements were distributed in Poland, which prevented an increase in thyroid cancer in the years afterwards (6). Other countries nearby which did not use iodine in the same way observed a significant increase in thyroid cancer following the nuclear disaster.
Cutting salt out of your diet can create iodine deficiency, but an iodine supplement can reverse it. Ever since excessive sodium intake was linked to high blood pressure, and by extension, an increased risk of heart disease, salt intake has declined.
A study published in 2010 in the American Journal of Hypertension noted that this decrease in sodium intake would necessarily lead to a decrease in iodine intake, because for many people, their primary source of iodine in their diet is through fortified salt (7).
According to the authors, women are particularly vulnerable to iodine deficiency that is the result of dietary salt restriction. The authors recommended that women (and possibly men as well) who are restricting their salt intake to decrease their blood pressure consider taking an iodine supplement to maintain adequate iodine levels.
If not, they could be at a higher risk for thyroid disorders. Fortunately, iodine is typically delivered in the form of potassium iodide, which has no tendency to raise blood pressure, even at the amounts in the highest-dose iodine supplements.
The side effects of iodine supplements can be serious, but only when massive doses of iodine are taken on a regular basis.
As noted earlier, very high doses of iodine in pregnant women have been associated with an increased risk of hypothyroidism during pregnancy, which can have negative health consequences for both the mother and the infant.
Some other thyroid problems, such as goiter, have been reported among people with extreme iodine intakes, though it requires massively exceeding recommended iodine intake levels (8).
The Office of Dietary Supplements at the National Institutes of Health has established upper limits of iodine intake of 1100 micrograms of iodine per day for both men and women.
You shouldn’t exceed this limit, since it may increase your risk of thyroid problems (9). Keep in mind that this is the limit for all iodine in your diet, not just your supplemental iodine intake.
Given its role in public health, the optimal dose of iodine for health is very well-understood, and has been determined for various different demographics.
According to the Office of Dietary Supplements at the National Institutes of Health, adult men and women need a minimum of 150 micrograms of iodine every day.
In women who are pregnant or breastfeeding, this jumps to a minimum of 220 micrograms per day. Iodine is fairly rare in foods that aren’t intentionally fortified, so it’s important that you make sure you’re getting at least the minimum recommended dose for optimal thyroid health.
Iodine plays a critical role in the synthesis of thyroid hormones. There’s a fine balance between the right amount of iodine and too much: in both cases, thyroid health is negatively affected, which can have both physical and mental health consequences.
Iodine levels are particularly important for women who are pregnant or breastfeeding, as iodine plays a critical role in infant development. These women should pay particular attention to their iodine levels and should take a moderate-dose supplement if their iodine intake is below the recommended 220 micrograms per day. If you are restricting your sodium intake, you are at particularly high risk of iodine deficiency, and you should strongly consider an iodine supplement.
All people should also be mindful not to exceed 1100 micrograms of iodine per day, as iodine intakes above this threshold are also associated with thyroid problems.