The thyroid gland in the neck produces thyroxine with the help of iodine, and many of the functions of specific cells are controlled by thyroxine.

Iodine has many benefits – a trace mineral critical to thyroid function, immune health, nervous system regulation, breast health, pregnancy and fetal development. But many people, even some doctors, do not consider iodine when considering critical nutrients for health and well-being. 

Iodine: what does it do?

Normal growth and brain development require iodine. A healthy diet needs sufficient iodine, but too much can be harmful.

The thyroid gland in the neck produces thyroxine with the help of iodine. Many of the functions of certain cells are controlled by thyroxine. As well as regulating protein, fat and carbohydrate metabolism in the body, thyroxine assists with bone and nerve growth.

Children and babies need iodine before birth and throughout their lives. It is essential for developing the brain and nervous system, coordination, alertness and the five senses

Do I need a certain amount of iodine?

It depends on your age and stage of life how much iodine you need:

Iodine can cause problems if there is not enough or too much. Insufficient iodine can cause extreme tiredness, coldness, difficulty concentrating and hair loss.

The thyroid gland may swell to form a goitre without enough iodine. It appears as a lump in the neck.

For people with thyroid disorders, too much iodine (usually from supplements) can be harmful.

What is the best way to get enough iodine?

Food is a source of iodine. Seafood such as oysters, snapper and seaweed are high in iodine. Iodine is also found in tinned salmon, bread, eggs, milk and milk products such as yogurt.

It is also added to many types of salt. You can check the information on the label.

Additionally, iodized salt is now used in bread making. Iodine content will be indicated on the packaging.

What kinds of dietary iodine supplements are available?

Iodine is found in dietary supplements, typically in potassium iodide or sodium iodide [1]. There is a lot of iodine in multivitamin-mineral supplements. There are also dietary supplements containing iodine-containing kelp (a seaweed).

How does iodine affect health?

Health scientists are studying iodine to determine how it affects the body. Here are some examples of what research has shown:

Iodine and pregnancy

Make sure you consume enough iodine during pregnancy. A low iodine level can increase the risk of miscarriage. The baby may also suffer from stunted growth and intellectual disability.

The National Health and Medical Research Council of Australia likewise recommends that all pregnant women, breastfeeding or considering pregnancy take an iodine supplement of 150 micrograms a day to increase their intake. Otherwise, they will likely get only some of the daily iodine. 

During pregnancy, many Australian women do not get enough iodine, so taking a supplement during the planning phase until the end of breastfeeding is essential. It is recommended that pregnant women avoid kelp (seaweed) supplements since they may contain high levels of iodine and heavy metals such as mercury [2].

Fetal and infant development

During pregnancy and breastfeeding, pregnant women and their babies need sufficient iodine to grow and develop. Breastfed infants get iodine from breast milk. However, the iodine content of breast milk depends on how much iodine the mother gets.

Iodine supplements are recommended by several national and international groups to ensure adequate levels of iodine are available for the proper development of a fetus and infant during pregnancy and breastfeeding. During pregnancy or while breastfeeding, the American Thyroid Association recommends taking a daily supplement containing 150 mcg of potassium iodide iodine.

The American Academy of Pediatrics has comparable guidance. In the US, only half of prenatal multivitamins contain iodine.

Cognitive function during childhood

In childhood, a severe iodine deficiency harms the brain and nervous system. Childhood iodine deficiency is more difficult to measure, but mild iodine deficiency can affect neurological development in subtle ways.

Taking iodine supplements improves the reasoning abilities and cognitive function of children with mild iodine deficiency. Supplements help children living in areas with low iodine levels develop physically and mentally. Further research is needed to determine whether mild iodine deficiency and iodine supplements affect cognitive function.

Fibrocystic breast disease

In spite of the fact that it is not risky, fibrocystic breast disease causes lumpy, painful breasts. It is more common among women of reproductive age, but it can also occur during menopause. 

Fibrocystic breast disease may be relieved by very high doses of iodine supplements, but more research is needed to confirm this. It is important to check with your healthcare provider before taking high doses of iodine for this condition.

Radiation-induced thyroid cancer

People who are exposed to radioactive iodine, especially children, can develop thyroid cancer as a result of nuclear accidents that release radioactive iodine into the environment. The risk of thyroid cancer is especially high for people with iodine deficiency who are exposed to radioactive iodine. As a thyroid-blocking agent, potassium iodide has been certified by the US Food and Drug Administration to lessen the risk of thyroid cancer in radiation emergencies.

Is my iodine intake sufficient?

In the United States, food and beverages are the main sources of iodine. There are, however, certain groups of people who are more likely to have difficulty getting enough iodine:

• Those who do not use iodized salt: The most widely used method of controlling iodine deficiency is to add iodine to salt. Globally, about 88% of households use iodized salt.
• To provide enough iodine for their babies, pregnant women need about 50% more iodine than other women. Many pregnant women in the US aren’t getting enough iodine, but experts aren’t sure whether this affects their babies.
• Vegans eat few or no dairy products, seafood or eggs. Although, these are among the best sources of iodine.
• Those residing in regions with iodine-deficient soils eat mostly local foods. Mountainous areas, such as the Himalayas, the Alps and the Andes regions, and river valleys in South and Southeast Asia, have the lowest concentration of iodine in their soil.
• Those who consume goitrogen-containing foods and get marginal amounts of iodine. A goitrogen interferes with the body’s ability to use iodine. Soy and cruciferous vegetables like Brussels sprouts, cabbage, broccoli and cauliflower contain them. Most people in the US receive adequate amounts of iodine, so eating foods containing goitrogens is not a problem.

[1] https://ods.od.nih.gov/factsheets/Iodine-Consumer/#
[2] https://www.healthdirect.gov.au/iodine#:~:text=Iodine%20helps%20the%20thyroid%20gland,in%20babies%20and%20young%20children.