The Best Sources of Iodine for Your Diet

November 24, 2025 •

4 min read

Iodine is an essential trace mineral that the human body cannot produce on its own. An adult requires about 150 micrograms (mcg) of iodine per day to ensure proper thyroid function. Given its crucial role in metabolism and overall health, understanding what are the best sources of iodine is vital for maintaining a balanced diet.

Quick Summary

This guide details the top food sources of iodine, including seafood, dairy products, and fortified salt, which are essential for thyroid health and preventing deficiency. It compares iodine content and offers tips for incorporating these nutritious options into your daily meals.

Key Points

Seaweed is a superior source: Varieties like kelp and nori contain exceptionally high concentrations of iodine.
Dairy products provide significant iodine: Milk, yogurt, and cheese are reliable contributors to iodine intake, particularly in Western diets.
Iodized salt is a key fortifier: It is a simple and effective way to ensure adequate iodine intake, unlike specialty salts such as sea salt and Himalayan salt.
Seafood offers abundant iodine: Lean fish like cod and shellfish such as shrimp and oysters are rich sources of this essential mineral.
Pregnant and breastfeeding women have higher needs: They must pay special attention to their iodine intake to support proper fetal and infant brain development.
Supplementation should be approached with caution: The iodine content in kelp supplements can be highly variable and potentially excessive; consult a healthcare provider first.
A varied diet is the best approach: Prioritizing whole foods rich in iodine is the safest and most effective strategy for most people.

Why iodine is a critical mineral for your health

Iodine plays a fundamental role in human health, primarily through its function in producing thyroid hormones, specifically triiodothyronine (T3) and thyroxine (T4). These hormones are crucial regulators of your body's metabolism, controlling energy conversion, temperature, and overall cell function. Beyond metabolic control, adequate iodine intake is particularly vital during pregnancy and infancy, as it supports proper fetal and infant bone and brain development. Severe iodine deficiency during these stages can lead to intellectual disabilities, cretinism, and stunted growth.

For adults, insufficient iodine can result in a range of issues. The most visible symptom is often a goiter, which is an enlargement of the thyroid gland in the neck. Other symptoms of hypothyroidism related to low iodine levels include unexplained weight gain, fatigue, dry skin, sensitivity to cold, and constipation. While many countries have successful iodized salt programs to combat deficiency, recent shifts towards specialty salts like sea salt or Himalayan salt, which are often not iodized, have led to a re-emergence of mild iodine deficiency in some populations.

Top dietary sources of iodine

To ensure your diet provides sufficient iodine, focusing on a variety of foods is key. The richest sources are found in the ocean, as most of the world's iodine is concentrated in seawater.

Seafood and sea vegetables

Seaweed: Without a doubt, seaweed is one of the most potent natural sources of iodine. Kelp, in particular, can contain extraordinarily high levels, but amounts can vary widely by species and origin. Other types like nori and wakame also provide significant amounts.
Cod: Lean fish like cod are an excellent option for those seeking dietary iodine. A 3-ounce serving of baked cod can provide a significant portion of the daily recommended intake.
Shellfish: Shrimp, oysters, and other shellfish naturally absorb iodine from the sea, making them reliable sources for boosting your intake. For example, three ounces of cooked shrimp provides around 35 mcg of iodine.

Dairy products

Dairy products are another major source of iodine, especially in Western diets. The iodine content is influenced by the iodine in the feed given to the animals, as well as the iodine-containing disinfectants used in milking.

Milk: A single cup of nonfat milk can provide more than half of the adult daily value for iodine.
Greek Yogurt: A dense source of nutrients, a cup of Greek yogurt contains a notable amount of iodine.
Cheese: Different types of cheese contain varying levels of iodine. Cottage cheese tends to be a good source, with one cup offering a considerable amount.

Fortified and other foods

Iodized Salt: The most widespread and effective method for preventing iodine deficiency on a population scale is the use of iodized salt. A quarter teaspoon of iodized table salt contains a significant amount of iodine, making it an easy way to meet daily needs. However, specialty salts like sea salt are typically not iodized.
Eggs: Eggs are a reliable source of iodine, with most of the mineral concentrated in the yolk. A single large hard-boiled egg can contribute a good percentage towards your daily goal.
Enriched Grains: Some bread products are made with iodate dough conditioners, which can significantly increase their iodine content. This practice is common in some regions as a fortification strategy.

Comparing iodine content: Fortified vs. natural sources

It's useful to compare the iodine content of different sources to understand how they can fit into your diet. While naturally occurring sources like seafood offer a concentrated boost, fortified foods and iodized salt play a critical role in ensuring consistent, daily intake, especially for those who consume limited seafood or dairy. The table below provides a comparison of approximate iodine values per serving.


Source	Serving Size	Approximate Iodine Content (mcg)	Notes
Kombu Seaweed	1g dried	Up to 2,984 mcg	Highly variable; use sparingly to avoid excess.
Baked Cod	3 oz	146 mcg	A lean protein source.
Greek Yogurt	3/4 cup	87 mcg	A versatile dairy option.
Nonfat Milk	1 cup	84 mcg	A staple in many diets.
Iodized Salt	1/4 tsp	78 mcg	An easy way to fortify meals.
Large Egg	1	31 mcg	Most iodine is in the yolk.
Shrimp	3 oz	13 mcg	A good shellfish source.

How to choose the right sources for your diet

Your iodine strategy should be personalized based on your diet and lifestyle. For those who frequently eat seafood and dairy, meeting the daily recommended intake is typically straightforward. For others, especially individuals following vegetarian or vegan diets, planning is more important to avoid deficiency. Vegan sources like prunes and lima beans offer smaller amounts, so relying on fortified plant-based milk alternatives or a balanced supplement might be necessary.

When considering supplements, it is crucial to exercise caution. The British Dietetic Association and others warn that seaweed or kelp supplements can contain inconsistent and often excessive levels of iodine. The best approach is to consult a healthcare professional to assess your individual needs. For most healthy adults, prioritizing dietary sources is the safest and most effective way to maintain adequate iodine levels. The Dietary Guidelines for Americans also emphasize that meeting nutritional needs primarily through whole foods is the best strategy. You can explore more nutritional guidelines from the National Institutes of Health.(https://ods.od.nih.gov/factsheets/Iodine-Consumer/)

Conclusion

Iodine is a vital mineral required for the production of thyroid hormones, which regulate metabolism and are essential for neurological development in infants and children. The best sources of iodine come primarily from seafood, dairy products, and iodized salt. Other contributors include eggs and certain fortified grains. While supplements are available, it is recommended to meet iodine needs through a balanced diet to avoid inconsistent dosing and potential harm from excessive intake. By incorporating a variety of these iodine-rich foods into your meals, you can support your thyroid health and overall well-being. For those with dietary restrictions, like vegans, careful meal planning or considering fortified products and professionally guided supplementation is a prudent strategy.

Frequently Asked Questions

Seaweed, especially kombu kelp, is often considered the single best food source of iodine due to its extremely high concentration of the mineral.

It can be more challenging for vegans to get sufficient iodine, as many of the richest sources are animal-based. Vegans can use iodized salt and seek out iodine-fortified plant-based milks or supplements, though a healthcare professional should be consulted.

No, only table salt labeled 'iodized' contains added iodine. Specialty salts like sea salt, kosher salt, and Himalayan salt are typically not iodized.

Iodine deficiency can lead to hypothyroidism, which causes the thyroid gland to enlarge (a goiter) and results in symptoms like weight gain, fatigue, and dry skin.

Yes, excessive iodine intake, particularly from high-dose supplements like some kelp tablets, can also cause thyroid dysfunction. The tolerable upper limit for most adults is 1,100 mcg per day.

Dairy products contain iodine from two sources: the natural content in the animal feed and iodine-based disinfectants used during the milking process.

Most adults need about 150 micrograms (mcg) of iodine per day. This amount increases for pregnant and breastfeeding women.

Yes, though in much lower concentrations. Plant-based sources include prunes and lima beans. Fortified foods are often the most reliable vegan options.

While some iodine can be lost during cooking, the amount is generally small. Using iodized salt as part of your regular seasoning remains an effective way to contribute to your daily iodine intake.