Iodine: Benefits, Recommended Intake, & Side Effects

by Meenakshi Nagdeve last updated - Medically reviewed by Emily Borth(MS, RDN)

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Around 70-80% of the iodine in the human body is stored in the thyroid gland. It plays a very important role in the normal functioning of the thyroid gland, which secretes thyroid hormones that control the base metabolic rate of the body. In fact, without it, thyroid hormones could not even be synthesized. It also helps in the brain and bone development of the baby during pregnancy and early childhood.

In this article, let us take a look at what is iodine, what are its deficiency symptoms, the recommended intake, and how it is good for your health.

What is Iodine?

Iodine is an essential trace element that naturally occurs in the earth’s soil. It is also known as iodide. It is important for your thyroid gland as it helps in the production of hormones. The human body cannot produce iodine, which is why it is important to include iodine-rich foods in the diet. It is mostly found in iodized salt and seafood.

Many countries like the United States, Canada, and Australia have salt iodization programs to curb the deficiency.

Seaweed on a plate

Iodine is found in large amounts in seaweed like kombu, nori, wakame, and kelp. Photo Credit: Shutterstock

Signs and Symptoms Of Iodine Deficiency

Iodine deficiency can have serious effects on the growth and development of the body. The symptoms of this deficiency include the following:

  • Reduced thyroid hormone production and hypothyroidism
  • Goiter (enlarged thyroid gland)
  • Intellectual disability
  • Stunted infant growth
  • Abnormal weight gain
  • Decreased fertility
  • Dry skin
  • Growth retardation in the fetus and increased risk of stillbirth or miscarriage in expectant mothers
  • Constipation
  • Fatigue

In severe cases, intellectual disability associated with diseases such as cretinism, characterized by physical malformations, can be the result. According to WHO reports, this deficiency is one of the leading causes of intellectual disability all over the world.

Groups that are at a high risk of this deficiency are people living in areas with iodine-deficient soils, pregnant women, and people who tend to consume very less iodized salt.

Important Sources of Iodine

Iodine is found in large amounts in seaweed like kombu, nori, wakame, and kelp. It is also present in a notable amount in seafood like cod liver, tuna, shellfish, and whitefish.

Dairy products like yogurt and milk and eggs are also known to contribute to your iodine intake.

Swiss chard, summer squash, sesame seeds, soybeans, turnip greens, and spinach are the other important sources of iodine, especially for vegans and vegetarians. The amount varies depending on the type of soil they grow in. Also, the same factor is responsible for the iodine content of meat products.

Iodized salt is another important source of iodine. Bakers regularly add iodine to bread dough as a stabilizing agent, so you can also include baked goods in your diet.

Iodine is also present in infant formulas and breastmilk.

Here is a detailed article on the sources of iodine.

Iodine Benefits

This element is required to ensure proper development and metabolism in humans. The specific health benefits include:

Protects Thyroid Health

Iodine is an important mineral that keeps your thyroid gland healthy.

The thyroid gland helps in regulating your hormone production, which helps improve your metabolism and heart health.

When the thyroid gland does not get enough iodine, hormone production decreases. At this time, an under-active thyroid gland can lead to a condition called hypothyroidism. It results in the general slowing down of all bodily processes as the chemical balance in the body goes off track. Including iodine-rich foods in your diet can help to keep this disease at bay.

On the other hand, an overactive thyroid produces more hormones than required. This condition is known as hyperthyroidism. At such times, a different form of iodine known as radioactive iodine is recommended by medical experts to help reduce excessive thyroid hormones.

May Help Prevent Goiter

Many a time, hyperthyroidism or hypothyroidism can cause your thyroid gland to become enlarged. This condition is known as goiter. It may also happen due to iodine deficiency.

If the goiter is mainly due to lack of iodine, doctors often suggest including foods that are rich in iodine to make up for the loss.

Helps Regulate Metabolic Rate

Iodine helps the thyroid gland by assisting in the production of hormones, which are responsible for controlling the body’s base metabolic rate.

Metabolic rate affects the efficacy of the organs and regular processes like the sleep cycle, and the absorption of food and its transformation into usable energy.

Certain hormones, like thyroxine and triiodothyronine, influence heart rate, blood pressure, body weight, and temperature. The body maintains BMR (Basal Metabolic Rate) with the help of these hormones, which also helps in protein synthesis. Ensuring their normal creation and distribution in the body is key to maintaining good health and iodine is a crucial component of these hormones.

Helps Improve Fetal Health

Iodine is considered as one of the important nutrients during pregnancy.

A sufficient quantity of iodine in pregnant women is essential to help prevent stillbirths or neurocognitive conditions like cretinism in newborn babies.

A proper fetal development party depends on iodine sufficiency. Research shows that even a mild deficiency can have harmful effects on the infant as it can cause growth retardation, both mental as well as physical.

To accommodate the needs of your unborn child or infant, the recommended intake is suggested to be 220 mcg/day during pregnancy and 290 mcg/day during lactation.

Neurodevelopment during Pregnancy

Iodine is often linked to lower IQ in many kids.

A meta-analysis of 6180 children between 1.5 and 8 years of age was conducted to test this. The IQ of three birth cohorts from Spain, the United Kingdom, and the Netherlands were assessed. The results of this study suggested that verbal IQ was lower in children if their mothers had a lower iodine status in the first trimester.

If you are pregnant, consult with your doctor about its intake and supplementation to avoid its deficiency.

Infant Health

One problem that many breastfeeding women face is not realizing that they must consume additional iodine for the child and themselves as well. Because it passes into breast milk, the intake of iodine is recommended after including both the mother and child’s requirements.

Studies show that when pregnant or nursing women consume low iodine, the effects show on the baby’s health.

Infant formulas contain this nutrient. If you think you are not able to consume enough iodine or pass it on to your baby, talk to your doctor about other ways to supplement it.

Boosts Immune System

Iodine helps boost the overall immunity levels in the body as it is a scavenger of free radicals.

According to a review published in the journal Nutrition, iodine plays “a role in the physiology of the inflammatory response,” as well as an antioxidant role. Like vitamin C, it also shows antioxidant activity throughout the body which helps provide a strong defensive measure against various chronic diseases.

Fibrocystic Breast Disease

Iodine deficiency is often linked to the occurrence of fibrocystic breast disease. In this condition, the breast tissues become thick, giving it a lumpy texture.

Although it is non-cancerous, fibrocystic breast disease is associated with an increased risk of developing breast cancer. Studies have shown a significant correspondence between molecular iodine and a reduction in the signs of fibrocystic breast disease.

Anticancer Potential

Including iodine-rich foods in your diet may help you prevent cancer.

Recent research published in the Asian Pacific Journal of Cancer Prevention shows that iodine deficiency may be a possible cause of breast and stomach cancer. The study was conducted on 85 Iranian cancer patients. Results showed that these people had a severe iodine deficiency based on the index by WHO and UNICEF.

Researchers of this study suggest including iodized salt and other iodine-containing foods to help lower the risk of cancer.

May Help Prevent Thyroid Cancer

Animal studies show that prolonged iodine deficiency can increase the incidence of thyroid cancer.

Iodine sufficiency is also linked to a lower risk of radiation-induced thyroid cancer. Nuclear accidents lead to a release of radioactive iodine into the environment. Research shows that if a person is already suffering from its deficiency, the uptake of this radioactive iodine becomes high in this individual as the thyroid is iodine-deficient.

The Centers for Disease Control and Prevention recommends using potassium iodide (KI) to protect the thyroid gland from radiation injuries in such emergencies.

Iodine May Also Help In:

  • Disinfecting water when you are traveling or staying at places where municipal water treatment is not reliable.
  • Treating and preventing infections around wounds and scrapes.
  • Treating foot ulcers in people with diabetes.

Recommended Intake

The amount of iodine your body needs differs based on age.

The daily recommended intake by the Food and Nutrition Board (FNB) at the Institute of Medicine of the National Academies for individuals according to their age is as follows:

  • Birth – 6 months: 110mcg
  • 7 – 12 months: 130 mcg
  • 1 – 8 years: 90 mcg
  • 9 – 13 years: 120 mcg
  • 14 and above: 150 mcg
  • Pregnant and lactating women: 220 mcg and 290 mcg, respectively

Side Effects of Excessive Iodine Intake

Iodine is safe for you as long as you consume it in a recommended amount. Too much iodine can lead to:

  • Nausea and vomiting
  • Fever
  • Stomach pain
  • Diarrhea
  • Burning sensation in the mouth and throat

In extreme cases, when an individual has taken too much of this element, it may result in coma, iodine poisoning, or toxicity. It could also result in thyroid papillary cancer. The National Cancer Institute also found that long term use of iodine for treatment of hyperthyroidism can, in turn, be a potential cause of cancer.

Iodine also reacts with certain medications like anti-thyroid medications, angiotensin-converting enzyme (ACE) inhibitors, and potassium-sparing diuretics. Speak to your doctor before including a new supplement if you are taking any of these.

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About the Author

Meenakshi Nagdeve, Co-Founder, Organic Facts is a health and wellness enthusiast and is responsible for managing it. She has completed the Nutrition And Healthy Living Cornell Certificate Program, Cornell University, US. She holds a Post Graduate Diploma in Management from IIM Bangalore and B. Tech in Metallurgical Engineering and Materials Science from IIT Bombay. Prior to this, she worked for a few years in IT and Financial services. An ardent follower of naturopathy, she believes in healing with foods. In her free time, she loves to travel and taste different types of teas.

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