Iodine is an essential nutrient, meaning that the human body requires it for many essential functions but cannot synthesize it on its own. Without enough iodine, the thyroid gland cannot produce the thyroid hormones that regulate growth, metabolism and other important processes in the body. When that happens, energy levels plummet, hormones become imbalanced, and physical and emotional states are affected. Here we’ll take a closer look at everything you need to know about iodine and its special relationship with the thyroid.

Why Is Iodine Essential for Your Thyroid?

The thyroid is a butterfly-shaped endocrine gland situated at the front of your neck below the larynx (voice box). Dubbed the “master gland,” your thyroid plays a critical role in your health. The thyroid gland needs iodine to manufacture thyroid hormones, most notably triiodothyronine (T3) and thyroxine (T4). The shortened names refer to the number of iodine molecules these hormones contain, T3 has three iodine molecules T4 has four. T3 and T4 regulate your body’s metabolism. Heart, brain, and muscle function all depend on thyroid hormones like T3 and T4.

Iodine and Thyroid Disorders

According to the American Thyroid Association, roughly 20 million Americans have some form of thyroid disease, and about 12 percent of the total US population can expect thyroid disease to arise sometime during their lifetime. For those currently afflicted with a thyroid disorder, more than half aren’t aware of it.[1]

Iodine and Hypothyroidism

Hypothyroidism refers to an underactive thyroid that does not produce enough thyroid hormones. Nearly five percent of the U.S. population over twelve years of age has this endocrine disorder, with a significantly higher incidence in women than in men and people over the age of 60.[2] Symptoms, which may be mild at the onset, include[2]:

• Fatigue
• Depression
• Unexplained weight gain
• Intolerance to cold temperatures
• Brittle nails
• Muscle and joint pain
• Goiter (swelling of the thyroid gland)
• Low blood pressure
• Elevated cholesterol

Without intervention, symptoms may later progress to include:

• Irregular menstrual periods
• Puffy face, hands or feet
• Impaired hearing
• Hoarseness
• Dry skin and hair
• Thinning hair

While genetic factors, congenital disabilities, autoimmune disorders such as Hashimoto’s disease, thyroid surgery, radiation treatment, pregnancy, or the long-term use of certain medications can also cause hypothyroidism, iodine deficiency is the most common cause throughout the world.[3, 4, 5]

Where iodine-rich foods are widely available, the most common cause of primary hypothyroidism is autoimmune thyroiditis, an inflammation of the thyroid gland.[5] Secondary hypothyroidism is the term used to refer to an underactive thyroid due to the failure of the pituitary gland to signal thyroid hormone production through the release of thyroid-stimulating hormone (TSH).[6]

Iodine and Hyperthyroidism

An overactive thyroid causes hyperthyroidism. With this condition, the thyroid releases excess thyroxine (T4), leading to a metabolic imbalance. Less than two percent of the U.S. population has this condition. Women are 2-10 times more likely to develop hyperthyroidism than men. Individuals over the age of 60 are also at increased risk, as well as people with type I diabetes, adrenal insufficiency, thyroiditis, ovarian or testicular cancer, a family history of thyroid disease, or pernicious anemia due to a deficiency or malabsorption of vitamin B-12.[7, 8] The most common cause of hyperthyroidism in the US is, however, Graves’ disease, an autoimmune condition that occurs 7-8 times more frequently in women than in men.[9]

Because thyroxine regulates metabolism and how the body uses energy in virtually every cell in the body, symptoms that are likely to present early on include fatigue, nervousness, increased appetite, irregular or rapid heartbeat, difficulty sleeping, mood swings, trembling, muscle weakness and unexplained weight loss.[7, 8] Other symptoms of an overactive thyroid include:

• Goiter
• Menstrual disorders
• Flushing of the skin
• Intolerance to heat
• Diarrhea
• Hair loss
• Protruding eyes

Left unchecked, hyperthyroidism may increase the risk of heart disease, stroke or osteoporosis. Hyperthyroidism can also cause Graves’ ophthalmopathy, a condition that may result in eye pain, light sensitivity, double vision and, in rare cases, loss of vision.[7]

For people with hyperthyroidism, iodine reduces hormonal secretion, although scientists do not yet understand precisely how or why.[10] Studies found that injections of iodine in hyperthyroid patients successfully slowed down thyroxine production.[11] Sometimes radioactive iodine is used in severe cases.[7] Treatment depends on how severe the condition has become so always consult your healthcare provider for guidance.

How Much Iodine Do I Need?

For healthy individuals, the amount of iodine you need each day depends on your age and is measured in micrograms (mcg). According to the Office of Dietary Supplements of the National Institutes of Health (NIH), the daily recommended amount of iodine in micrograms (mcg) is as follows:[12]

• Infants birth-6 months:  110 mcg (if not breastfeeding)
• Infants 7-12 months:  130 mcg (if not breastfeeding)
• 1-8 years:  90 mcg (if not breastfeeding)
• 9-13 years:  120 mcg
• Teens >14 and adults:  150 mcg
• Pregnant women:  220 mcg
• Breastfeeding women:  290 mcg

Given the range of critical functions that iodine supports, many healthcare specialists believe that these recommendations are too low. Note that if you have a thyroid condition, whether hypothyroidism or hyperthyroidism, your healthcare provider’s specific recommendations for iodine intake may vary from these standard recommendations. In some cases, taking iodine can worsen your condition so be sure to check with your provider.

How Iodine Deficiency Affects the Thyroid

Iodine deficiency is a serious issue and the number one cause of preventable disabilities in the world. The World Health Organization estimates that around 1 billion people will suffer from some form of health issue due to a lack of iodine in the diet, and approximately 40% of the world’s population is at risk for iodine deficiency.[13, 14, 15] Although table salt has been iodized since 1924, iodine deficiency is rising again in the Western world. A 1998 report found that iodine deficiencies had increased in the United States during the previous 20 years, likely due to dietary changes.[16]

Insufficient iodine intake directly affects the thyroid since T3 and T4 hormones require this essential mineral. If you do not have enough iodine, you can not produce enough of these two thyroid hormones. These iodine-containing hormones are used for brain, heart, muscle, and bone maintenance and functioning, as well as metabolism – turning food nutrients into the energy needed for the body and its organs to work properly.

How Do I Know if I am Iodine Deficient?

While thyroid function is easily measured, there is no specific blood test to determine how much iodine is circulating in your body. However, since the kidneys eliminate iodine, healthcare providers can assess iodine intake by measuring its concentration in urine.[13] Doctors can conduct blood tests for levels of thyroid hormone and thyroid-stimulating antibody immunoglobulin (TSI) levels. An iodine deficiency is suspected when thyroid hormones fall below a normal range. The appearance of a goiter also indicates either a deficiency or overabundance of iodine.

Iodine, the Thyroid, and Pregnancy

During pregnancy, elevated levels of estrogen and human chorionic gonadotropin (hCG) hormones trigger an increased release of thyroid hormones, which are required for the baby’s proper brain and nervous system development. Rarely, pregnancy-induced Graves’ disease will send the thyroid into overdrive, leading to hyperthyroidism. Symptoms include fatigue, difficulty sleeping, and irritability and physicians and pregnant women often overlook them as normal pregnancy concerns. Hyperthyroidism during pregnancy can lead to high blood pressure (preeclampsia), anemia, low birth weight and other conditions.[17]

Hyperthyroidism can also occur after giving birth. Also, thyroid inflammation, or postpartum thyroiditis, may occur after childbirth and trigger hyperthyroidism, especially in women with type I diabetes.[17] Fatigue and mood swings are often attributed to postpartum blues and ignored, so if these symptoms persist, be sure to contact your healthcare provider.

Sources of Iodine

If you want to ensure you get adequate iodine, it can be obtained from food or supplements. Iodine is also present in iodized table salt.

Iodine in Food

There are many iodine-rich foods. Shellfish and saltwater fish, such as tuna, are excellent sources of this trace mineral. Seaweed, namely nori, kelp, and dulse are high in iodine.[13] Eggs and meat also contain iodine.

Dairy products made from cow’s milk, including yogurt, cheese, and ice cream, contain iodine foods, although by accident as well as by design. Many dairy farmers use an iodine-containing saline solution to clean the cow’s teats and collection equipment that can find its way into milk.[18] Farmers also feed dairy cows grains that contain iodine.

Iodine occurs naturally in fruits and vegetables as a result of being taken up through the soil. However, its concentration in plants depends most on the region in which the produce was grown and the iodine content of that particular region’s soil.

Iodine in Salt

Iodized salt usually contains potassium iodide in the range of 76mcg per ¼ teaspoon of salt, as well as 580mg of sodium. However, because table salt carries health concerns, I recommend Himalayan crystal salt, which has variable levels of iodine, though it is not added unnaturally as iodized salt is. Be aware that processed foods, such as canned soups and vegetables, or packaged frozen meals, rarely contain iodized salt.

Iodine Supplements

To ensure a regular and consistent supply of iodine, many people consider an iodine supplement to be among the most important of nutritional supplements. There are a few different forms, such as potassium iodide and sodium iodide.

I recommend nascent iodine, also known as nano-colloidal iodine or atomic iodine. The latter name refers to the incomplete number of electrons in its structure, resulting in the ability to hold an electromagnetic charge. The term “nascent” means new, freshly made, and applies to this form of supplement because it is produced via an electrolytic process. This proprietary method ensures a consumable form of iodine that the body readily absorbs and uses to maintain optimal iodine levels and to support thyroid health. Another distinction about this form of iodine supplement is that it is a mono-elemental, meaning that it is not bound to other elements (potassium iodide contains potassium and iodine), which makes it easily recognized and used by the body.