Iodine and Thyroid Function: How This Sea Mineral Supports Our Hormone Health
The thyroid gland is one of the most quietly influential organs in the human body. Nestled at the base of the neck, this butterfly-shaped gland produces hormones that regulate everything from metabolism and energy to mood and temperature balance. To do its job properly, the thyroid relies heavily on one key nutrient: iodine.
At HerbEra, we believe in exploring wellness through both science and tradition. Iodine is a trace mineral with an outsized role in hormone health, and it’s especially vital for supporting thyroid function. While many of us are aware of iodine’s link to thyroid hormones, there’s a lot more to this essential nutrient than meets the eye.
In this article, we’ll explore 10 fascinating facts about iodine, its relationship with thyroid health, where you can find it in food, and which herbs can be rich sources of this sea mineral.
10 Fascinating Facts About Iodine
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We take most of our iodine with milk. Interestingly, milk that cows produce in winter is richer in iodine than in summer.
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French painter Louis Daguerre used iodine to make the first photographs, ‘daguerreotypes’. It occurred in 1839, and for approximately twenty years, it was the most popular method of taking photos.
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You can use iodine to detect starch. If you suspect that yogurt contains starch, drip some liquid iodine over it. The mineral will color the substance deep blue if it contains any starch.
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The word ‘iodine’ originates from the Greek ioeidēs, which means ‘violet colored’. While solid iodine is dark blue, almost black, it becomes purple when vaporized.
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Iodine has been used to purify water, as it may promote a healthy microbial balance.
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Some sea animals, like turtles, can sense iodine. It helps them find food in the ocean.
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Your brain needs iodine. Iodine-rich food might promote cognitive health, so consider eating some sushi or other seafood before important exams. Another option is to consume some vitamin B12.
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Iodine is relatively rare in both the atmosphere and the Earth’s crust; however, it’s abundant in seawater.
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Certain foods can block iodine uptake. These “goitrogens” include raw cruciferous vegetables like cabbage and Brussels sprouts, though only when eaten in very large amounts.
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Iodine was discovered in 1811. A French chemist Barnard Courtoi was trying to extract potassium and sodium from seaweed when a cloud of purple gas appeared.
Iodine and Thyroid Function
The thyroid gland uses iodine to produce two critical hormones: thyroxine (T4) and triiodothyronine (T3). These hormones regulate the body’s metabolic rate, support digestion, influence heart function, and affect nearly every cell in the body. Without enough iodine, the thyroid can’t produce adequate amounts of these hormones, potentially leading to thyroid imbalances.
When iodine intake is insufficient, the thyroid may work harder to trap iodine from the bloodstream, often resulting in enlargement of the thyroid gland. While it is less common in areas where iodine is abundant, iodine deficiency remains a global concern, especially among women of childbearing age and populations without access to iodized salt or iodine-rich diets.
Key benefits of iodine for thyroid function
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Supports the synthesis of T3 and T4 hormones
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Helps maintain inner balance
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Contributes to temperature regulation
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Supports neurological development (especially during pregnancy)
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Just like iron, iodine plays a role in healthy energy levels and mood stability. Another beneficial element for the nervous system is magnesium.
It’s important to note that too much iodine can be just as problematic as too little. Excessive iodine intake may contribute to imbalances in thyroid hormone production, especially in sensitive individuals. This makes it all the more important to aim for moderate, food-based iodine intake — and to work with a healthcare provider when considering iodine supplements.
Foods Rich in Iodine
Incorporating iodine-rich foods into your diet is a natural and sustainable way to support thyroid health. Here are some of the most reliable dietary sources.
Seaweed
Perhaps the most famous iodine-rich food, seaweed includes varieties like kelp, wakame, and nori. A little goes a long way: just a small serving of seaweed can meet or exceed daily iodine requirements.
Cod
Cod is a mild white fish and an excellent source of iodine. It’s also low in fat and high in protein, making it a heart-friendly choice for those looking to support overall wellness.
Shrimp
Shellfish like shrimp contain iodine thanks to their ocean environment. They also offer additional nutrients like zinc and selenium, both of which play supportive roles in thyroid function.
Eggs
Eggs, especially the yolk, contain moderate amounts of iodine and are easy to include in most diets. They also offer high-quality protein and healthy fats.
Dairy
Milk, yogurt, and cheese provide iodine in many Western diets. The amount varies depending on farming practices, but dairy remains a convenient source for many.
Herbs Rich in Iodine
Beyond food, herbs can be an additional source of iodine, especially when wildcrafted or grown near the sea. Here are a few plant allies traditionally known for their natural iodine content and support for thyroid wellness.
Kelp (Laminaria spp.)
Kelp is one of the richest natural sources of iodine. As a sea vegetable, it’s often included in thyroid support formulas and tinctures. In addition to iodine, kelp offers other trace minerals, including magnesium, calcium, and potassium.
How to use: Add kelp to salads, rice, or fish dishes, boil in soups or dashi (the base for Japanese miso soups). You can also consume it in a Kelp Tincture.
Black Walnut (Juglans nigra)
Black walnut hulls are rich in tannins and iodine and have traditionally been used in herbal formulations for cleansing and balance.
How to use: Black walnuts are a great snack; you can also add them to salads, sauces, or desserts. To consume black walnut hulls, you can infuse them with herbal teas. Another way is taking Black Walnut Capsules or a Black Walnut Tincture.
Yellow Dock (Rumex crispus)
Yellow dock root is commonly used in herbal detox and mineral support blends. It supports liver function and mineral absorption. Besides, yellow dock is rich in iodine, which makes it a valuable ally in whole-body wellness, including thyroid balance.
How to use: You can infuse it with herbal teas or consume it by taking Yellow Dock Capsules or a Yellow Dock Tincture.
Conclusion
Iodine may be a trace mineral, but its impact on thyroid health — and the body as a whole — is anything but small. Iodine and thyroid play a key role in promoting energy levels and hormonal balance.
While no single food or herb can act as a magic bullet, there’s incredible power in consistency, variety, and quality. At HerbEra, we encourage a holistic approach: eating iodine-rich foods, including sea-based herbs like kelp, and exploring plant-based formulations that respect both science and tradition.
Whether you’re supporting your thyroid during a specific season of life or simply seeking a deeper understanding of your body, iodine is a mineral worth paying attention to. And with so many natural sources available — from cod to kelp to black walnut — it’s easy to bring this essential nutrient into your wellness practice with mindfulness and care.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.