What You Need to Know about Iodine

What You Need to Know about Iodine 1

Iodine is an important trace mineral that doesn’t get the recognition and respect it deserves. That may be because our exposure to iodine typically consists of seeing the words “iodized salt” but the nutrient is actually under out feet-it is present in most soils, where it is taken up by plants that are eventually eaten by animals and people.

But what else should you know about iodine? Do you realize how it can impact your health?

Why we need iodine

Iodine is an essential micronutrient for everyone, and especially pregnant women and their infants. The body requires iodine for the balanced production of thyroid hormones, which are responsible for controlling the body’s metabolism, bone health, the healthy progression of pregnancy, the neuropsychological development of the fetus, and support of immune function.

Although iodine and the thyroid gland have an intimate relationship, only about 30 percent of the micronutrient is found in this organ. The remaining amount can be found in the cervix, eye, gastric mucosa, mammary tissue, and salivary glands. Little research has been done to uncover the role of iodine in these areas, although more has been done with the breasts. As for the part iodine plays in other body tissues, one idea is that iodine performs antioxidant functions and helps clear disease-causing free radicals.

Read more about ways to get iodine in your diet

Iodine and the breasts

Iodine and the breasts have a relationship on several levels. For one, the breasts concentrate the mineral to a greater degree than does the thyroid gland, and human milk contains an iodine concentration fourfold that of the thyroid tissue. Experts believe this is nature’s way of supporting neonatal thyroid function and normal brain development.

Iodine has a role in treating a painful breast condition called fibrocystic breast. Several studies show that taking iodine can relieve the pain and help maintain normal breast tissue function.

Iodine also may have a role in breast cancer, and one relationship appears to involve abnormal levels of thyroid hormones. Further research is needed, but it has been shown that significantly higher levels of thyroid hormones and antibodies can be seen in people with breast cancer than in healthy individuals.

In animal studies, the use of iodine alone or with progesterone has shrunk breast tumors. Other research has shown that different kinds of human breast cancer cells treated with seaweed induced apoptosis (cell death).

Iodine deficiency

Are you getting enough iodine? Is iodine deficiency a problem? The answers to these questions depend on which people you are talking about and the severity of the deficiency. According to a new report in Environmental Geochemistry and Health, 32 countries in the world have iodine deficiency, including many European developed countries.

The National Institutes of Health calls iodine deficiency “uncommon” in the United States and Canada. Yet according to the findings of the National Health and Nutrition Examination Surveys, 11 percent of people in the United States are deficient in iodine. Of special interest is that more than 7 percent of pregnant women and nearly 17 percent of all women of reproductive age do not have enough iodine.

The authors of a 2014 report have noted that “Recently, even in developed countries such as UK, USA, and Australia, moderate iodine deficiency has re-emerged as an important public health concern, likely due to a change in eating habits of the population.” The same experts also pointed out that even mild levels of iodine deficiency can have an adverse effect on pregnancy or the neurocognitive development of the baby.

In fact, severe iodine deficiency in pregnant women is the most common cause of preventable brain damage. It also can cause delayed sexual development and stunted growth in children. Less severe deficiencies can lead to a lower-than-average IQ in kids and reduce an adult’s ability to work and think clearly. Individuals with an iodine deficiency often have an enlarged thyroid gland (goiter) or can experience weight gain, fatigue, gastrointestinal problems, skin abnormalities, and cold intolerance.

Causes of iodine deficiency

What can cause an iodine deficiency? A combination of factors can be involved. For one, not everyone uses iodized salt. In fact, the makers of refined and processed foods typically do not, and that includes fast foods.

A significant source of iodine was removed from the food supply several decades when the baking industry began using bromine-based anti-caking agents instead of iodine-based ones.

Substances called halides can cause a deficiency as well. Halides are the chemical reduction of halogens, which include bromine, chlorine, fluorine, and iodine. Two of the halides (bromide and fluoride) are harmful because they interfere with the action of thyroid hormones and iodide. Therefore, when you drink fluorinated water, fluoride can bind to iodine receptors and block your use of the mineral. In addition to breads, bromide can be found in personal care products, pesticides, some prescription medications, plastic products, and citrus-flavored beverages.

People who are at risk of iodine deficiency include vegetarians and vegans, individuals who eat little or no fish, shellfish, and/or seaweed, and those who have significantly reduced or eliminated their use of iodized salt.

Iodine needs

For balanced thyroid hormone production and to avoid deficiency problems, the following intake of iodine is recommended:

  • Infants birth to 1 year: 110-130 micrograms (mcg) daily
  • Children ages 1 to 8 years, 90 mcg/day
  • Children 9 to 13 years, 120 mcg/day
  • Males and females 14 years and older, 150 mcg/day
  • Pregnant and lactating females, 220 and 290 mcg/day, respectively

Sources of iodine

Table salt that has been fortified with iodine is the most obvious source of the mineral. The general government standard for adding iodine to salt is 76 to 77 micrograms of the trace mineral per gram of salt, although the actual amount may be closer to 45 to 50 micrograms. To translate this into real terms, there are 6 grams of salt per teaspoon, so at 45 to 50 mcg/g you can expect to get 270 to 300 mcg of iodine, much more than the recommended daily amount for most people.

Since it is recommended that you get your iodine (and other vitamins and minerals) from food, which foods should be on your menu?

Certain sea vegetables, such as kelp and wakame, can provide about 500 percent of your daily requirement for iodine in just one tablespoon! More common sources include cod and scallops (excellent sources), yogurt, shrimp, eggs, cow’s milk, and strawberries (very good), salmon, sardines, and tuna (good). Plants get iodine from the soil, so fruits, vegetables, grains, and beans and legumes do contain small amounts of the mineral. If you suspect you may be low in iodine, check with your healthcare provider.

Read about seaweed as an iodine source

Other thoughts on iodine

  • According to Nobel Laureate Albert Szent Gyorgyi (who discovered vitamin C in 1928), iodine “protects against abnormal growth of bacteria in the stomach (Helicobacter pylori is the most clinically significant).”
  • David Derry, MD, PhD, author of Iodine and Breast Cancer, has stated that “iodine and thyroid hormones act as a team to provide a constant surveillance against abnormal cell development and the spread of cancer cells within the body.”
  • An iodine tincture (2% iodine and 47% alcohol) can be used to purify water to make it drinkable.
  • Potassium iodide (K1), the most soluble form of iodine, can be used to prevent the thyroid from taking up radioactive iodine in the event of exposure to radioactivity or radioiodines. K1 floods the thyroid with non-radioactive iodine and stops the uptake of radioactive molecules, thus protecting the gland.
  • Although it is rare, too much iodine intake can cause enlargement of the thyroid gland. This can occur in people who eat a lot of seaweed.

Image: TheGiantVermin


  • Beth Israel Deaconess Medical Center
  • Caldwell KL et al. Urinary iodine concentration: United States National Health and Nutrition Examination Survey 2003-2004. Thyroid 2008 Nov; 18(11): 1207-14
  • Caldwell KL et al. Iodine status in pregnant women in the National Children’s Study and in US women (15-44). National Health and Nutrition Examination Survey 2005-2010. Thyroid 2013 Aug; 23(8): 927-37
  • Mercola.com. Signs, symptoms and solutions for poor thyroid function
  • National Institutes of Health, Office of Dietary Supplements
  • Patrick L. Iodine: deficiency and therapeutic considerations. Alternative Medicine Review 2008; 13(2)
  • WH Foods, iodine
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Deborah is a freelance health writer who is passionate about animals and the environment. She has authored, co-authored, and written more than 50 books and thousands of articles on a wide range of topics. Currently, she lives in Tucson, Arizona.