Iodine Deficiency

In this Article (Index)

• What is Iodine?
• Essential Nutrient Mineral
• Iodine Deficiency
• Recommended Daily Allowance
• Iodine sources and content in foods
• Dairy products
• Risks from plant-based milks
• Iodized Salt

What is Iodine?

Iodine is a chemical element. Its symbol is I. Its atomic number is 53, meaning that it has 53 protons in its nucleus.

It was discovered by accident in 1811 by Bernard Courtois, a French chemist. The French government, led by Napoleon Bonaparte was at war with Britain, and desperately needed a new way to produce saltpeter, a basic ingredient for gunpowder. Courtois set out to find one.

Saltpeter (or potassium nitrate) was normally made from wood ash, but wood was becoming scarece so, Courtois used ash made from seaweed, that was abundant along the coast of Normandy where he lived. As he refined his ash, something began corroding his copper vats. He managed to separate this unknown substance by adding sulfuric acid to the ash. It formed bright purple-black crystals that precipitated in his vats. He published his discovery in the Annales de Chimie in 1813 in an article titled "Decouverte d'une substance nouvelle dans le vareck," or "Discovery of a new substance in seaweed."

Joseph Louis Gay-Lussac named it iodine after the Greek word ιωδη&sigma (iodes), which means "violet."

Iodine is a halogen, like chlorine and at room temperature is a non-metallic solid. It is very scarce in nature, comprising only 0.46 parts per million of Earth's crust. It is the 60th most abundant element.

Essential Nutrient Mineral

Iodine is an essential nutrient, meaning that it is necessary for life.

Iodine is a used by the thyroid gland to synthesize hormones like triiodothronine (T3) and thyroxine (T4) that regulate the body's metabolism, the production of its proteins, the activity of enzimes, and is critical for the development of unborn babies during pregnancy and later, as infants.

Iodine Deficiency

The source of iodine is through the diet, by eating foods that contain Iodine.

Lack of iodine, or iodine deficiency, can lead to stunted growth and cognitive issues due to arrested nervous system development.
Iodine deficiency affects 1 out of every 4 people in the world.

One indicator of this deficiency is goitre or goiter, a swelling in the neck that is the outcome of an enlarged thyroid gland. When iodine levels fall, the gland's tissue grows as it tries to obtain more iodine. It is frequent in inland areas, far from the sea (seafood and seaweed are good sources of dietary iodine).

The word goitre comes from the Latin term gutturia for throat.

Supplementation with iodine is a remedy for goiter and iodine deficiency. Over 120 countries around the world have implemented iodine fortification of salt as a tool to prevent iodine deficiency.

Recommended Daily Allowance

The Recommended Daily Allowance in the U.S. is 150 mcg for both men and women over the age of 14 years. For pregnant women the value is increased to 220 mcg, and for those lactating, 290 mcg.

Excessive intake of iodine should be avoided because it can provoke thyroid gland disorders.

Iodine Sources

Iodine enters the body by ingesting food that contains it.

Seaweed (kelp, nori, kombu, and wakame) are excellent sources of iodine. Fish, seafood and eggs also provide it. Fruits and vegetables are poor sources.

Milk and dairy products are an important source of iodine. This is because their feed is fortified with iodine and part of this passe into the milk.

Another source is the red dye used in foods, FD&C Red No. 3 which is an organoiodide compound that is restricted as a food additive in the UK, the EU, and China. Australia and New Zealand limit its use. In the U.S. it can be used freely.

Eating a balanced diet will provide the necessary amount of iodine for a healthy life.

Iodine content in food

Average quantity of iodine in different foods. (1)

Sea food and fish, seaweed, are excellent sources of iodine, but for people living far from the sea, or those who don't fancy eating this type of food, milk and dairy products is an alternative. Another sourceo of iodine is iodized salt: 1 teaspoon covers the daily needs of an adult.

Pregnant women should take supplements to ensure the correct intake of iodine.

Dairy Products

Milk, yougurt, butter, and cheese are all good sources of iodine. The natural iodine in the soil on which the cows graze ends up in their milk. But cows are also supplemented with feed that contains iodine, and this is the main source of iodine for cows. Iodine content in milk is variable and depends on many factors. For instance, it is 44% lower for organic milk produced in winter vs. conventional milk; and UHT mikls contain 27% less iodine than regular pasteurized milk. (2)

Two cups of milk cover an adult's daily allowance of iodine. However, vegetarians and vegans don't drink milk and are at a risk of iodine deficiency.

Risks from plant-based milks

Plant-based milk substitutes (almond and soy milks) contain very small amounts of iodine. A recent study in the U.K.(3) analyzed over 100 samples of plant-based and dairy milk. They found that "iodine concentrations in dairy milk is ten times higher compared to plant based milks." A similar ratio was found in cheese, butter and yogurt.

Several plant-based milks were fortified with iodine, but even then, their iodine content was lower than those found in milk.

The study revealed that people eating an average diet ingested betwen 123 and 329 μg per day from dairy sources, covering their recommended daily intake. However those using plant-based milk obtained only 21.8 μg per day, roughly 15% of the necessary daily intake for adults.

Iodized Salt

Goiter was common in the U.S. in the Appalachians and Great Lakes regions, they were known as the "Goiter Belt." In 1922, David Cowie, chairman of the Pediatrics Department at the University of Michigan, suggested at a thyroid symposium that salt iodization should be implemented to erradicate this disease.

Salt manufacturers fortified table salt and it reached consumers in 1924. However many opposed to salt fortification and a 1948 Goiter-elimination bill that made it mandatory across the nation was defeated.
Currently 70 to 76% of American households consume iodized salt. (4)

Many salt producers in the U.S. add iodine but do so on a voluntary basis. Since most salt in the American diet comes from processed foods, and food manufacturers don't use iodized salt, iodine deficiency is a cause of concern.

Specialty salts like sea salt, kosher salt, Himalayan Salt, and fleur de sel, are not usually iodized. The natural iodine content of these salts is low; a study in New Zealand showed that non-iodised salt less than 1 - 3.5mcg per g. (5)