Name: Iodine

Symbol: I
Atomic Number: 53
Relative Atomic Mass: 126.90
Category: Halogen (Group 17)
Appearance: Black orthorhombic solid, violet-gray gas

Above: Image © istockphoto.com/3dalia

Can salt help raise your I.Q.? According to a New York Times article, it can. Iodine deficiency (a lack of iodine) can cause poor brain development. But what exactly is iodine? And why is it important to your health?

Iodine was discovered by accident in 1811.The French chemist Bernard Courtois was trying to make salt by burning seaweed. He treated the seaweed ashes with acid to remove impurities. However, Courtois added too much sulphuric acid to his seaweed ashes. Clouds of purple gas appeared! Scientists further studied this gas. Eventually, they identified it as a new element: iodine.

Iodine exists in two different forms. Elemental iodine consists of two iodine atoms bonded together (I2). This form can be toxic when eaten directly! However, when iodine bonds with other elements to create a compound (such as potassium iodide), it’s safe to eat. You can buy these compounds at drug stores. They’re also often added to the salt you eat.

Did you know? Iodine deficiency is the leading preventable cause of mental and developmental disabilities worldwide.

When you eat iodide, your thyroid gland makes hormones that control your body’s metabolism. If you don’t get enough iodine in your diet, you can end up with some serious health problems. For example, you can get a condition called goitre. This is when the thyroid gland enlarges and stops working properly. A lack of iodine can also cause cretinism (stunted physical and mental growth). More generally, low iodine in the diet can lead to problems thinking clearly. It can even lower your I.Q.!

Did you know? Processed foods are not made with iodized salt.

Pregnant women who don’t get enough iodine can have babies with many problems. These babies might have delays with physical growth, mental development and sexual development. Doctors often encourage pregnant women to take iodine supplements. This helps make sure the fetus grows and develops properly.

Many other countries (including Canada) are keeping the iodine deficiency problem under control. How? By iodizing food - especially salt! However, iodine deficiency is still a problem in mountainous areas of central Asia and the Andes. These areas have low levels of iodine in their soil.

Be careful, though: too much iodine isn’t good, either. Strangely enough, it can cause symptoms similar to those of iodine deficiency! Adults should be getting around 150 micrograms per day.

Did you know? Kosher and sea salt contain little or no iodine.

Remember: iodine is an important part of your diet. It is key to your growth, your physical health and your intellect. Get your daily dose of iodine through seafood, dairy products, and vegetables grown in iodine-rich soil. And the next time you add salt to your food, make it iodized salt!

This article was updated by Let's Talk Science staff on 2016-06-22 to improve readability by reducing the reading grade level.

Learn more!

Food Sources of Iodine (2014)
Dieticians of Canada

Information on recommended intake and sources of iodine.

Iodine Deficiency (2014)
Stephanie L. Lee, Medscape

Overview of iodine deficiency and related medical conditions, including goitre and cretinism.

Iodized Salt (2013)
Salt Institute (industry association)

Article discussing iodized salt and its role in the fight against iodine deficiency.

Iodine status of Canadians, 2009 to 2011 (2013)
Statistics Canada

Statistics related to iodine level and iodine deficiency in Canadians.

Iodine: Fact Sheet for Consumers (2011)
US National Institutes of Health

General introduction to iodine and its role in human health.

Periodic Table Live! (2010)
Chemical Education Digital Library

Information on the characteristics, discovery, sources, and uses of all elements in the periodic table. Click on element number 53 to learn more about iodine.

Jina Kum

I am a graduate student at Western University. Born in South Korean, I moved to Toronto at the age of 6 and have lived in Canada since then. I enjoy camping - especially the campfire and the stars! I love science because it helps to explain the natural world, from why sky is blue to how we can generate new treatments to fight diseases. 


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