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Are You at Risk for Iodine Deficiency?

Find out what iodine does for you, how to tell if you’re getting enough, and the best food sources for this essential nutrient.

By
Monica Reinagel, MS, LD/N, CNS,
July 10, 2013
Episode #242

Nutrition Diva fan Gregory writes, “I have read that iodine deficiency is becoming more and more common. Is this true and, if so, what is the best way to get iodine?”

According to the World Health Organization, iodine is the most common nutrient deficiency—affecting 2 billion people around the world. It’s really a shame, because iodine is cheap and the costs of iodine deficiency (both in financial and human terms) are large.

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Why Do You Need Iodine?

Your body needs iodine in order to produce thyroid hormone, which regulates growth and development in fetuses and children and regulates metabolism in adults. Iodine deficiency is especially dangerous (and especially common) during pregnancy, when it can cause problems with the infant's neural development and lead to mental retardation. In fact, iodine deficiency is the biggest preventable cause of mental retardation in the world.

Some researchers have also linked low iodine levels during pregnancy to an increased risk of ADHD in kids. Low iodine levels may also lead to stunted growth, sluggish metabolism and weight gain, thyroid disease, or fibrocystic breast disease in women.

Is Iodine Deficiency on the Rise?

The introduction of iodized salt back in the 1920s largely eliminated iodine deficiency as a public health concern here in the U.S. and in other developed nations. But now, some health professionals worry that if the sodium police get their way and people really start cutting back on salt, an increase in iodine deficiency could be an unintended consequence. 

See also: Is Salt Bad For You?

Iodized salt remains the primary source of iodine in the American diet. But even though average salt consumption is twice the recommended level, iodine intake has actually declined about 50% over the last 30 years. How can that be? Well, we used to cook at home, using iodized salt. Today, most of the salt we consume comes from packaged and processed foods—and manufacturers are not required to use iodized salt. And among those who do still cook at home, fancy sea salts (which are not iodized) have become more popular. Sure, enough, several recent studies have found that iodine deficiency appears to be on the rise.

See also: What Kind of Salt is Healthiest?

Who is at Risk?

In the U.S., the rates of iodine deficiency in the overall population hover around 10%, but some groups have a higher risk. Up to a third of pregnant women, whose iodine requirements are higher, are deficient. Vegetarians and vegans are more likely to be deficient than meat eaters. Iodine is also lost in perspiration, so heavy exercisers may need more iodine to replace what is lost in their sweat.

The classic sign of iodine deficiency is an enlarged thyroid gland, or goiter. The thyroid gland sits right in the middle of your neck so it’s pretty easy to see when it gets enlarged. Before the days of iodized salt, goiters were actually quite common in the U.S., especially in areas where iodine levels in the soil are naturally low. Although they remain common in many parts of the world, you don’t see a lot of people with goiters in the U.S. anymore. However, the absence of a goiter doesn’t guarantee that you’re getting enough iodine. Your best strategy is just to be sure that your diet provides adequate iodine.

Where to Get Iodine

Using iodized salt is one obvious solution, but what are the best natural food sources of iodine? The iodine content of soil varies a lot from region to region, as does the iodine content of the vegetables grown in that soil. So, while vegetables can be a decent source, you can’t really count on them. Dairy products are a more reliable source because iodine is added to the feed for dairy cows. Seafood and edible seaweeds, such as wakame, are also good sources. In fact, dried kelp granules, which are often sold as a salt substitute, are an especially potent source of iodine.

See also: Is Seaweed Good For You?

Should You Take an Iodine Supplement?

Even though iodine intake has declined, the vast majority of people are still getting the recommended amount. If you’re pregnant (or hoping to become pregnant) or have some other reason to be concerned about your iodine status, a multi-vitamin containing iodine will ensure that you have your bases covered. But don’t go overboard with the supplements (or sea vegetables).

As I discussed in my episode, Can You Get Too Many Vitamins, more is not always better. Although iodine is needed for healthy thyroid function, too much iodine can also interfere with your thyroid.

Keep in Touch

If you have a suggestion for a future show topic or would like to find out about having me speak at your conference or event, send an email to nutrition@quickanddirtytips.com. You can also post comments and questions on my Nutrition Diva Facebook Page. I answer a lot of listener questions in my free weekly newsletter, so if you’ve sent a question my way, be sure you’re signed up to receive that.

References

Hypertension, dietary salt restriction, and iodine deficiency among adults. Tayie FA, Jourdan K.Am J Hypertens. 2010 Oct;23(10):1095-102.

Attention deficit and hyperactivity disorders in the offspring of mothers exposed to mild-moderate iodine deficiency. Vermiglio F, Lo Presti VP, et al. J Clin Endocrinol Metab. 2004 Dec;89(12):6054-60.

Iodine uptake and loss-can frequent strenuous exercise induce iodine deficiency? Smyth PP, Duntas LH. Horm Metab Res. 2005 Sep;37(9):555-8.

Iodine deficiency in vegetarians and vegans. Krajcovicová-Kudlácková M, Bucková K, at al. Ann Nutr Metab. 2003;47(5):183-5.

Iodine nutrition in the United States. Trends and public health implications Hollowell JG, Staehling NW, et al. J Clin Endocrinol Metab. 1998 Oct;83(10):3401-8.

Iodine nutrition: iodine content of iodized salt in the United States.

Dasgupta PK, Liu Y, Dyke JV. Environ Sci Technol. 2008 Feb 15;42(4):1315-23.

Sea salt image from Shutterstock

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