Iodine Sources and Functions

ocean beach

Iodine Sources and Functions

All of the nutrient minerals work together to keep you healthy and feeling good. Here is a summary of the role of the trace mineral, iodine, in your good health.

What it does Part of two thyroid hormones that help regulate growth and metabolism
Daily needs [Infants: 110-130 µg][Children: 90-150 µg] [Men: 150 µg] [Women: 150 µg] [Pregnancy: 220 µg][Lactation: 290]
Not enough Weight gain; Hypothyroidism; Goiter; Cretinism in infants
Too Much Nausea, diarrhea, vomiting, weakness; Goiter
Foods Iodized salt, seafood, dairy, bread, seaweed, vegetables grown in soil rich in iodine

*The lower value is for infants up to 6 mos., higher value is for infants up to a year old.
† The first value is for children 1-3 with the amount increasing until age 18.

Just a trace

Note that the adequate daily intake of iodine is given in micrograms (µg). A microgram is .0001 milligrams (mg), so it is a very small amount. Only a trace of this mineral is needed, but it is nevertheless very necessary to your health.

Vital to thyroid function

The trace mineral, iodine, is a vital component of hormones produced by the thyroid gland that are responsible for a number of important functions in your body, including growth, metabolism, reproduction, nerve and muscle function, regulation of body temperature and blood cell production.

The thyroid gland is located in your neck and captures iodine from your bloodstream that came from the foods you eat. The thyroid relies on the hypothalamus and the pituitary gland to help regulate the amount of iodine captured by the thyroid and the production of those all-important, iodine-containing thyroid hormones.

It comes from the ocean

Most of the iodine on the planet is found in the oceans. It therefore follows that seafood, including seaweed, are rich sources of iodine. Even the water supply in coastal areas is a source of iodine.

Iodine is also present in the soil in which we grow our food. However, the iodine content of the soils varies so greatly, that it is difficult to say which foods will be significant sources of iodine.

Fun Fact for Iodine Sources and Functions: If you live by the ocean, the misty air you breathe can be a source of iodine. Enjoy those fresh, salt breezes along with some of this important trace mineral!

Iodized Salt

Early in the last century, the problem of iodine deficiency was addressed in some developed countries, such as the U.S. and Canada, with the introduction of “iodized salt.” Since that time, iodine deficiency has become less common, and in fact, the problem of too much iodine had to be addressed with the advent and popularity of salty fast foods and processed foods. The food industry is trying to deal with this issue by using regular salt rather than iodized salt in their food processing.

There is some controversy about the use of processed salt—the only kind that is iodized. Although unprocessed salt has some naturally occurring iodine, there is some question whether it is enough to prevent deficiency, especially for the vulnerable groups such as pregnant and lactating mothers and children.

Fun Fact for Iodine Sources and Functions: To give you an idea of the minuscule amount of iodine you need, you can satisfy the RDA for iodine with about a half a teaspoon of iodized salt. Most of us consume a lot more than 1/2 teaspoon of salt each day!

Other sources

There is some iodine to be found in dairy products and baked products, such as bread, due to the way that these foods are produced. Iodine is added to animal feed and it shows up in the milk they produce. In addition there are some iodine compounds, such as dough conditioners used in breads, that are added to baked products. Some cereals and supplements are also fortified with iodine. If you are concerned or just curious, check the labels to see the iodine content.

Interesting Fact about Iodine Sources and Functions: Red food coloring contains iodine. However, eating red jelly beans is probably not the best way to meet your daily requirement!


When there is not enough iodine in the bloodstream, the body reacts by enlarging the thyroid gland. If the iodine deficiency continues, it could result in a condition referred to as “goiter,” in which the thyroid becomes so larges that it shows up as a bulge on the neck, under the chin. This condition is fairly common in areas of the world where iodine is not readily available in the soil, such as mountainous areas of South America and river valleys in Asia.

Interesting Fact about Iodine Sources and Functions: Believe it or not, a deficiency of iodine is considered the number one cause of preventable brain damage worldwide. This is due to the fact that besides its role in regulating growth, the thyroid hormone is vital to proper development of the brain before and after birth.


If severe iodine deficiency occurs during pregnancy, it can result in a tragically irreversible condition called “cretinism.” The infant suffering from cretinism will have severe physical and mental retardation.

Too much iodine is also possible

An excess of iodine, oddly enough can lead to some of the same problems as a deficiency of iodine. In either case, the thyroid does not function properly, leading to possible enlargement and to developing goiter. Iodine toxicity is rare and usually associated with supplementation.

Caveat for Iodine Sources and Functions:  There are actually foods that when eaten in excess, can hinder healthy thyroid activity. For this reason they are called “goitrogens”, and include, cabbage, kale, spinach, rutabagas, broccoli, Brussels sprouts, peanuts, soybeans and even peaches and strawberries. Please keep in mind that all of these foods are excellent sources of nutrition, and are only a problem if eaten in excess.

The upper intake level for adults (who are not pregnant or nursing) for iodine that has been established is 1100 µg per day.

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