What's up with iodized salt - Is it better for you than regular salt?

Dear Alice,

What is it with iodized salt? We just bought a pound of salt and it is not iodized. Are we at some risk for dreaded ailments? Since a pound of salt lasts FOREVER at our house, should we re-consider and get the iodized version?

Wondering

Dear Wondering,

Great question! Iodine is a mineral that is added to table salt and found in a variety of foods. It is important for good health and, fortunately, our bodies require it in relatively small quantities. Iodine is part of a hormone, thyroxin, which is responsible for maintaining a person's metabolic rate.

Iodine is found in the sea and in soil that has previously been under the sea. Salt water seafood (e.g., sea trout, lobster, haddock, shrimp, and shark), sea vegetables (such as seaweed, including kelp, hijiki, arame, nori, and laver), vegetables grown in soil containing iodine (found on any land that was previously under the sea), and animals grazing on plants growing in iodine rich soil all are good sources. This mineral also enters the food supply through the use of certain disinfectants called iodophors. These are primarily used in the dairy industry, so milk and cheese, for example, contain a good amount of iodine. In addition, some red dyes contain iodine, as do some dough conditioners (look for an iodized conditioner listed in the ingredient section on the bread package). These sources add considerable amounts of iodine to one's diet.

Seafood is a good source of iodine.

As you can see, there are many ways to obtain iodine other than through table salt. That was not always the case. Many years ago, when iodine wasn't as plentiful in the food supply and people relied on iodine mainly from the sea, many people in the Great Plains states and Willamette valley in Oregon in the United States, which are situated far from salty waters, had iodine deficiency. Salt fortification was initiated in the U.S. to eliminate goiter, a disease of the thyroid gland resulting from iodine deficiency.

A woman suffered from goiter (enlargement of the thyroid gland). 

Now, food is manufactured and shipped all over the U.S. and the world. Food containing iodine is available everywhere. It is much less likely for people, even those living far from the ocean, to have goiter nowadays. However, salt is still iodized because iodine levels can vary greatly in foods (as levels of iodine in the soil are quite variable), and fortification offers a margin of safety. Today, goiter is more prevalent in developing countries than in the U.S., because they don't have access to as many foods, such as plant foods, that were grown in iodine-rich soil, they aren't eating seafood, and the populations of some developing countries are malnourished in general.

So, in answer to your question, it sounds as though you and members of your household are probably not taking in much salt if that package lasts forever. If you are eating plenty of seafoods — saltwater fish and/or sea vegetables — you don't need to return your salt. If you are eating a varied diet, you are probably taking in sufficient iodine. However, if you avoid most of the foods mentioned here, you may want to reconsider getting iodized salt, just to be on the safe side.

The Recommended Dietary Allowance (RDA) for iodine is 150 micrograms (µg) a day for adults. Women who are pregnant should consume about 200-300 micrograms because iodine is important for fetal and infant brain development. Iodine content varies widely in foods, as shown in the following examples:

Food source  Iodine content (in µg)

Salt, iodized, 1 tsp.   400

Bread, made with iodized conditioner, 1 slice    142

Haddock, 3 oz.          104 - 145

Cottage cheese, ½ cup       26 - 71

Shrimp, 3 oz. 21 - 37

Cheddar cheese, 1 oz.        5 - 23

As a side note — lots of processed foods contain high levels of sodium. This sodium is not iodized, so don't count on meeting your iodine needs through chips and other junk food!

Do not count on chips for iodine. 

Go Ask  Alice!

* Go Ask Alice is the award-winning health reference website, fully produced and funded by Columbia University, seeks to provide reliable, accurate information in a sincere and sensitive way so people can make informed decisions about their health and well-being.  Go Ask Alice! receives over 1,000 very honest and frank questions each week in seven categories: alcohol and drugs, emotional health, fitness and nutrition, general health, relationships, and sexual and reproductive health. Every question is read, and each week a handful of health professionals give five new thoughtful and thorough answers. Questions come from students, parents, teachers, professionals, and other adults; however, most topics cover issues concerning college students.

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