Is Iodine Detrimental to the Thyroid? The Hypothyroidism Struggle

Can you heal your thyroid by eating iodine-rich foods? Or will that cause more harm than good if you have hypothyroidism?

This article will first cover the causes, symptoms, and diagnosis of hypothyroidism. Then examine the role of the thyroid gland on hormones. Next, look at research related to iodine and the thyroid. And lastly, discuss foods, vitamins, and minerals that may heal the thyroid, such as selenium and vitamin D.

Causes of Hypothyroidism

The most common form the hypothyroidism is Hashimoto’s thyroiditis (HT). With HT, the immune system creates antibodies that attack the thyroid gland.

Other causes of hypothyroidism include treatment for hyperthyroidism, thyroid surgery, radiation therapy, and certain medications. There are also less common causes, including congenital diseases, pituitary disorder, pregnancy, and iodine deficiency.

While not a problem in the US, hypothyroidism caused by Iodine deficiency still affects many developing countries.

Symptoms of Hypothyroidism 

Common symptoms include:

  • dry skin
  • weight gain
  • depression
  • constipation
  • tiredness
  • forgetfulness

While these symptoms may have several underlying causes, the symptoms are due to the body’s cells not receiving enough thyroid hormone for those with hypothyroidism.

Hypothyroidism is a lifelong disease. There is no true known cause. There is also no cure. Medication use is common but strides to find other methods that do not involve medication are goals for many with the disease.

Common Symptoms of Hypothyroidism

Diagnosis of Hypothyroidism

Many people are unaware they have hypothyroidism because the symptoms are so varied.

A doctor will diagnose hypothyroidism through an examination and laboratory tests. A test that measures TSH (thyroid-stimulating hormones) levels are given. If levels are elevated, it indicates hypothyroidism.

However, a study found in 3-8% of the population, TSH levels are in normal ranges, but the patient has symptoms of hypothyroidism. This is called subclinical hypothyroidism. Often subclinical hypothyroidism progresses to full-blown hypothyroidism.

Current Treatment for Hypothyroidism

The primary treatment for hypothyroidism is a Thyroxine (T4) medication. The medication needs to be taken for life. Thyroxine replaces the hormone that the body is no longer making.

The Role of the Thyroid Gland and Hormones

The thyroid is a small, butterfly-shaped gland found at the base of the neck. It is part of the endocrine system. The thyroid is responsible for releasing hormones into the bloodstream. It regulates many vital functions such as breathing, heart rate, and body weight. Metabolism regulation is a critical function of the thyroid gland. Many with the disease have difficulty losing weight, despite sufficient efforts.

When the body’s thyroid gland is underactive, it cannot make enough of the thyroid hormones, triiodothyronine (T3) and thyroxine (T4). These hormones help control one’s basal metabolism. When the body is not producing enough thyroid hormones, it can make losing weight harder. One study found that among obese patients, 33% had hypothyroidism.

What is Iodine Deficiency? 

Most table salt found in the US is now fortified with iodine.

While not a problem in the US, hypothyroidism caused by Iodine deficiency still affects many developing countries. Iodine is a micronutrient the human body cannot create. This means that iodine needs to come from food. Iodine is imperative for thyroid hormone production.

The deficiency of iodine was common up until the 1920s. It was discovered that there was a correlation between an enlargement of the thyroid gland and iodine deficiency. Goiter, an abnormal growth of the thyroid gland, is most commonly caused by iodine deficiency.

Once discovering the correlation between an enlarged thyroid and iodine deficiency, the United States and European countries started fortifying salt with iodine. This caused a significant decrease in the prevalence of the disease. However, according to the World Health Organization, one-third of the world’s population, around 2 billion people, do not fortify their salt and still struggle with iodine deficiency.

Iodine is essential during pregnancy. Inadequate intake may not only affect the mother but can lead to fetal hypothyroidism and interfere with fetus development. The most severe condition of fetal hypothyroidism is cretinism. This is a state of severely stunted physical and mental growth. Symptoms are dwarfism, physical deformities, and mental retardation.

The World Health Organization (WHO) recommends for adults 150 ug per day. 200 ug for pregnant and lactating women. And 90ug for children. Unless there is starvation occurring in developed countries, most people exceed the daily recommendation for iodine.

Do You Need Extra Iodine?

Many “online health experts” may promote ways to heal the thyroid. They suggest eating iodine-rich foods such as seaweed, eggs, and seafood because of the correlation between iodine and the thyroid. However, studies show excessive iodine intake is frequently associated with hypothyroidism. Too much iodine may make the condition worse.

According to one study, excessive iodine intake for five years resulted in excessive urinary iodine and an increase in hypothyroidism.

Another study conducted in a southern Italian village compared 1411 people from 1995 to 1148 in 2010, following the introduction of the salt iodization program. The rate of hypothyroidism was higher in 2010 vs. 1995 at 5.0 % vs. 2.8%, respectively.

The Key is a Balance of Iodine and a Healthy Diet

Balance is essential for iodine intake, and too much or too little may considerably affect thyroid function.

Many naturally iodine-rich foods are healthy. However, many foods with fortified table salt are unhealthy. Limit the intake of table salt and foods with added salt. Focus on getting iodine from healthy sources such as seaweed, eggs, and seafood.

Selenium and the Thyroid

The thyroid contains more selenium per gram of tissue than any other organ.

Selenium is vital for:

  • reproduction
  • DNA synthesis
  • protection from oxidative damage
  • thyroid hormone metabolism

There is a lack of studies on selenium and thyroid function. However, adding selenium-rich foods to the diet, such as shellfish, eggs, and Brazilian nuts, may benefit the thyroid gland. Brazilian nuts contain over 100% of the daily recommended value of selenium.

The thyroid contains more selenium per gram than any other tissue.

Vitamin D and the Thyroid

Vitamin D is a fat-soluble vitamin. It is naturally present in only a few food sources, such as fatty fish. The best source of vitamin D is sun exposure.

While a correlation between hypothyroidism and vitamin D deficiency has been found, the causation is still unknown. It is unknown if vitamin D deficiency causes thyroid problems or if the thyroid causes vitamin D deficiency. Incorporating vitamin D rich foods into the diet can be beneficial to the thyroid. Especially healthy foods such as fatty fish and eggs.

Nonetheless, supplementing with vitamin D is recommended for those with thyroid problems (Liontiris & Mazokopakis, 2017).

Supplementing and vitamin D rich foods can be beneficial to the thyroid

Are Brassica Vegetables Harmful to the Thyroid? 

The answer is no.

The Brassica family of vegetables includes cruciferous vegetables. Could cruciferous vegetables potentially decrease thyroid hormones? Potentially, but the amount consumed would have to be substantial. Vegetables such as collards, Brussel sprouts, and kale contain many goitrogens. Goitrogens can interfere with thyroid production in large quantities.

However, an average amount of cruciferous vegetables in the diet will not harm the thyroid. The harmful amount is >2.2 pounds per day for several months. The equivalent of over 11 cups of Brussel sprouts every day!

What Cruciferous Vegetables are Most Healing for the Thyroid? 

Broccoli, broccoli sprouts, and turnip tops are high in antioxidants.

Turnip tops, commercial broccoli, and broccoli sprouts contain fewer goitrogens than collard greens, Brussel sprouts, and kale. Even if consumed at high levels, the risk is minimal, with more health benefits than risk.

Furthermore, broccoli sprouts contain a high level of antioxidants. Broccoli sprouts are 3-4 day old broccoli plants. A study conducted on rats found that thyroid activity increased following the ingestion of broccoli sprouts. In rats with hypothyroidism, the broccoli sprouts had a beneficial influence on the thyroid gland.

Additionally, cruciferous vegetables are high in many other vitamins and minerals. Check out the Body Centric Life post on the benefits of green leafy vegetables and the importance of vitamin K.

Focus on Eating Healthy and Incorporating Thyroid Healing Foods

While hypothyroidism is a lifelong disease, it doesn’t have to control your life. Medication is an effective way to manage the condition and prevent additional problems.

In most developed countries, iodine deficiency is not the primary cause of hypothyroidism. Therefore, adding extra iodine to the diet is not recommended. Eat a healthy diet and incorporate thyroid-healing foods such as broccoli sprouts, Brazilian nuts, and fish into the diet when possible.