Curious About Iodine, Part 2: Beyond the Thyroid

The use of iodine dates back to 4th century China where seaweed and burnt sea sponge were effectively used to treat goiter. It was not until 1811 that iodine was isolated as a specific element that exhibited properties similar to the other halogens of bromine, chlorine, and fluorine. In 1829, Jean Guillaume Auguste Lugol, MD, introduced potassium iodide as an effective treatment for the effects of tuberculosis, and John Murray, MD, used iodine to treat croup, asthma, consumption, and other respiratory diseases [1].

Tincture of iodine has been a staple in every first aid kit for the treatment of wounds to prevent infection and support healing. Surgeons scrub up with a betadine solution and paint it on the body of those undergoing surgery to assure the skin is free of microbes. Over its long history, iodine has been used as an effective treatment for goiter, upper respiratory infections, asthma, and croup. It has also been used as an antiseptic, disinfectant, an expectorant, an amoebicide, and an anti-syphilitic remedy. Iodine has also been used topically for the treatment of various skin disorders [1].

Iodine Deficiency Disorder is the most common endocrinopathy in the world and is also the most preventable.

Iodine is a very versatile element in that its mechanism of action is somewhat determined by where it is stored in the body. The thyroid gland needs iodine to make thyroid hormones, which support growth, metabolism, and cognitive development, but iodine is also concentrated in numerous extrathyroidal tissues where it acts intracellularly as an antioxidant, supports cellular differentiation, has anti-inflammatory effects, and supports apoptosis [2].

Approximately 30% of the global population is iodine deficient due to reduced consumption and exposure to foods and environmental factors that inhibit iodine absorption. Let’s explore some of the basics about iodine – where we get it, common forms, symptoms of deficiency, and how much we actually need, not only to prevent deficiency, but to optimize tissue levels beyond what is needed to support thyroid function.

Sources of iodine

The oceans are the world’s main repository of iodine with some deposition in coastal soil due to volatilization of ocean water from ultraviolet radiation. Very little of the earth’s iodine is actually found in soil and the further we are from the coast, the lower the iodine content [3]. Food sources of iodine are seaweed (kombu, nori, kelp, wakame), seafood, iodized salt, dairy, eggs, baked goods made with iodate dough conditioner, breast milk, infant formula, beef liver and chicken [4].

Iodine versus iodide

Although iodide and iodine are used interchangeably, they are structurally and functionally different. Iodine and iodide are closely related terms because iodide is derived from iodine; however, iodine is a chemical element whereas iodide is an anion [5].

Iodine (I²) – Iodine rarely occurs as the single element seen on the periodic table. Iodine as I² is molecular iodine in which two atoms of iodine are bound together.

Iodide (I¯) – Iodide is the anion of iodine and typically binds to other elements to form a salt such as potassium iodide or sodium iodide. Iodide is formed from iodine with the addition of an extra electron.